This disscusion was brought up recently in another post. The topic has always puzzled me since there are many coments about such and such pump or set up not being suitable for hight HP applications because of a few psi pressure drop. I always theorized that if any positive pressure could be maintained to the HP pump during the desired situation then that would be sufficient. The main part to my theory was any positive pressure, consistency has nothing to do with it. If it were drag racing then it would need to overcome the G’s of launch and maintain a positive pressure for 13 or so seconds. If all we were concerened with was having a positive pressure then we could get by with a lot less pump than if we were looking for something to sustain a constant pressure over a certain situation. I theorize that if there is pressure drop in the rail(and there is) and the HP pump has any positive pressure then it’s not a problem with delivery to the HP pump. This could be something pretty easy to test I would think. Maybe something we could fool with at John’s open house? What do you guys think???


Here are some comments from other posts.....


My unit is set to 7 psi..... over a 20 second dyno pull with the TTS extreme it will drop to 5 psi. (Thats right folks 20 seconds


What has been documented with a Tech 2 is that the commanded fuel rail pressure of 23,000 psi is not being met or maintained with the big tunes. The first step in trying to maintain that pressure is to make sure the high pressure pump is being supplied all the fuel that it needs in order to do its job. Once we can maintain the supply side with a constant volume of fuel at some given pressure and then find that the high pressure pump still does not supply enough fuel to the engine to reach and maintain the commanded fuel rail pressure then we need to start looking at upgrading the high side pump. We could go to bigger injector nozzles and ignore the fact that the high side pressure is not there. Sure we flow more fuel at a lower pressure which makes more power but it's only a work around for the fact that our fuel system can't supply enough fuel to make the big power. It all comes down to pressure and orifice. Yeah, time is a factor as well but we'll cover that later.


Explain to me why there is a problem with fuel pressure dropping off as long as the pressure does not go to a negative pressure. After all aren't these trucks on a vacuum system in the first place?


The way I see it, is these lift pumps are just added insurance in the fuel delivery area. It does not matter if you are seeing 5psi or .5 psi as long as the truck is getting all the fuel it can use. Right? I mean as long as fuel is being sent back to the tank, there is no problem!


[QUOTE=ratlover] If the duramax system is designed to work in negative pressure and we are feeding it positive pressure(regardless of the drop and regardless of it being .5psi or 50psi) then any fuel issues are after were ever we are taking the LP measurment from correct. I am assuming there isnt a significant drop in pressure between the test port and the HP pump.....So it must be the HP pump correct? If i

Well, i do have the psi measuring stuff coming from Superflow as well as EGT and EVENTUALLY should have the ability to log fuel rail psi...

What happens on my truck (your results may vary) is that when my pressure fluctuates, that fluctuation is detectable in the HP pump. when you change the inlet pressure, even stays positive (like 7PSI down to 3) it seems to affect things. i know the pressure doesn't drop from inertia, as it happens on the dyno too.


if you have a tech 2 and a relay on your pump, you can manually fluctuate the pressure while keeping it positive with the truck at idle. you can then watch the tech 2 and see changes as the pressure fluctuates within a positive scope. because of that change i want a pump to hold a constant pressure, not just stay on the positive side. i can't remember the value i watch on the tech2, but if its important i can plug it in and figure it out again. remember my truck has seemed to always been weaker on the fuel system side...


Nick

One must first understand how the Hp pump works to understand why keeping constant fuel pressure is a problem. I've tried to explain it over and over but must not be doing a very good job of it. My recommendation at this point would be to purchase the Bosch design book like I did and I think with there explaination and pictures everyone will then understand. The short version is that the High pressure section of the pump uses the low pressure to control the high pressure output pressure. So if you move the low pressure up and down you move the high pressure up and down with it.

Steve,


well you just said what i was try to...

The transfer pump is a gear type pump which produces positive displacement. By adding a lift pump, we are simply overcoming pumping losses, and the inherent inefficiencies of this pump. We are also keeping the fuel in fluid form.


All we can really do by adding a lift pump is ensure that the transfer pump delivers maximum volume, and housing pressure to fill the high pressure side while hopefully maintaining some return flow.


It seems that at lower pump RPM's we need a little more help, and at higher pump RPM's a little less help to keep things full.


The big question is: Are we depleting the rail psi because the transfer side isn't keeping up, OR is it just a function of displacement of the high psi side of the pump???





I'll add (wlaking along the same lines as Nick was referring) that the more stable the flow and psi to the supply side of the injection pump, the easier it is for the FRPCV to do it's job...

The transfer pump is a gear type pump which produces positive displacement. By adding a lift pump, we are simply overcoming pumping losses, and the inherent inefficiencies of this pump. We are also keeping the fuel in fluid form.


All we can really do by adding a lift pump is ensure that the transfer pump delivers maximum volume, and housing pressure to fill the high pressure side while hopefully maintaining some return flow.





Unfortunately this is not the case, the transfer pump within the Hp pump assemble is a gear type pump but if you pour fuel into the inlet it pours out the outlet. I don't mean a little leaks by the gears! So far I've tested 5 different units and they are all the same. This is the same reason it will not self primp, if any air is introduced into the system it just quits working. So by adding a lift pump that holds consistent pressure we hold the same pressure at a minimum on the outlet side of the transfer pump and since this is what controls the high pressure it makes a big difference on how the system works.


Like I've said before if your truck is stock it's not necessary.

Gear type pumps displace fluid pure and simple thus the term positive displacement. Just like an oil pump when it turns, it must move fluid both in and out. It Doesn't matter where it goes, but it goes somewhere.


Adding lift supply helps to overcome the inefficiencies in this pump.


If it wasn't positive displacement, I doubt it could pull in excess of 30" hg at idle without cavitating...

I did quite a bit of searching but just came across what I think you were talking about. It still has me rather puzzle though as I’m not really understanding how the whole LP suction pump works and the HP pump is thus regulated. I’m not trying to start anything but one thread started out real informative and kinda fizzled out into an air in fuel debate. So how does it all work? Some say its positive displacement and some say it isn’t??? I think it being positive displacement or not makes a big difference. I’m not to hip on all that goofy stuff though. I can see how the frpcv could be infuenced with pressure fluctiations to the inlet of the LP side easier if it went positive displacemnt. But it sure looks like its positive displacemnt to mehttp://www.dieselplace.com/forum/smileys/Ermm.gif

I will say though that a positive displacemnt pump can have a bit of bleed by based on tolerances. Maybe this is why it has been comented that older units are helped by liftpumps more.


I have a question that may have some bearing on a wild thought i am having......what pressure ranges is the LP pump putting out in a happy factory system???

Approximately 60 psi relief pressure.Edited by: Kennedy

Since an oil pump has been brought into the discussion........... How come an oil pump of gear type design will self prime and the gear type Lp transfer pump will not?http://www.dieselplace.com/forum/smileys/Confused.gif





Answer is pretty simple, there are different! So just because they are both gear pumps is useless information and proves nothing!

Ok…..here is some of my thoughts, how far off base am I?

1 The LP pump is a positive displacement.

2 It is also a very inefficient pump because it is built fairly “lose” and this only gets worse over time. This also would account for being able to pour fluid through it.

You can get fluid to flow through a oil pump if the impellers arnt turning. You can also get gas past a roots type meter even though it is a very small amout because they are built to some crazy tight tolerances you can get a bit of bleed by past a roots style blower even though they are built to high tolerances and generaly have seals built onto the impellers.

I think I have changed my mode in thinking……

If the problem was between the fuel tank and the inlet to the LP pump than giving the LP pump’s inlet anything over negative pressure would fix it. I’m thinking the lift pump is a crutch for somewere between the LP pumps inlet and the HP pumps inlet. But its much cheaper to try to cram more fuel down its throat artificially. It should be easy to find out on a per truck basis though(since they seem fairly different in regards to efficency) what psi the inlet needs to see to make x HP. Pressure drop wont matter as long as it remains over x. For the inlet pressure I also don’t see the mode of regulation(frpcv) as being unable to react fast enough to the demand. If it’s a regulation problem it’s a total flow problem IMO and not that this pressure fluctuation or drop is making it hard for it to do its job although it may be the restriction. I dont really think its the HP pump becuase i dont see the lift pump helping it at all(although it may be undersized too I guess)



I still don’t have 100% grasp on how the system works. Is there a detailed version or schematic on the web or a manual I could get fairly cheap?

I still don’t have 100% grasp on how the system works. Is there a detailed version or schematic on the web or a manual I could get fairly cheap?








Buy the Bosch book. It's 50 pages of good information on how the system operates. It is not exactly what is used on the Duramax as GM modified it some but it will teach the inter-working of the High pressure pump and Low pressure transfer pump. Once you understand the relationship of the two things become much clearer. After that you can buy a pump and disassemble it and it teaches you more.

I still don’t have 100% grasp on how the system works. Is there a detailed version or schematic on the web or a manual I could get fairly cheap?











Buy the Bosch book. It's 50 pages of good information on how the system operates. It is not exactly what is used on the Duramax as GM modified it some but it will teach the inter-working of the High pressure pump and Low pressure transfer pump. Once you understand the relationship of the two things become much clearer. After that you can buy a pump and disassemble it and it teaches you more.








And the book is available from..........................





I like books, the covers taste good!

I purchased mine through SAE, but I would assume it can be purchased from Bosch as well.

I just caught something......30" of mercury at idel!?!?!? I believe every 1psi is 2.036" murcury colum.....unles I am screwed up again???http://www.dieselplace.com/forum/smileys/Confused.gifhttp://www.dieselplace.com/forum/smileys/Confused.gifhttp://www.dieselplace.com/forum/smileys/Confused.gif


Thanks. Do you remember the name of it? My surfing time is limited on some sites(figured i would try amazon) About how much did it set you back? Thanks again!

There are two books that have the common rail fuel system. The one I have is the smaller of the two.





Diesel acumulator fuel-injection system Common Rail


Technical Instruction





Alan "OC Dmax" bought the larger book with more information, you could PM him and get the name of that one.

Thankshttp://www.dieselplace.com/forum/smileys/Big Smile.gif


Steve wouldnt buy you the big book? You need to get on him about thathttp://www.dieselplace.com/forum/smileys/Clown.gif

I just caught something......30" of mercury at idel!?!?!? I believe every 1psi is 2.036" murcury colum.....unles I am screwed up again???http://www.dieselplace.com/forum/smileys/Confused.gifhttp://www.dieselplace.com/forum/smileys/Confused.gifhttp://www.dieselplace.com/forum/smileys/Confused.gif


Thanks. Do you remember the name of it? My surfing time is limited on some sites(figured i would try amazon) About how much did it set you back? Thanks again!








It destroyed my Kent Moore gauge!





The guy had a Holley red (gear type P-D pump) plumbed and wired backwards. Shut the pump off and it wrecked the gauge. Funny thing is, it still ran fine with the lift pump inop...

I don't claim to be a diesel tech or claim to know all there is about the Dmax fuel system. I have seen the GM animated video of how the pumps work. I have seen the drawings and a cut away. I do have a better than average amount of hydraulic training. We can call the LP pump several different names such prime/transfer/boost etc. It is a positive displacement pump period. It provides a given amount of fluid for every revolution. Their output volume, except for leakage, is independent of outlet pressure. There is always going to be some leakage around the gears both on the sides and around the out side. So when you pour fuel in one side it will run out the other. If we were trying to pump 10 GPM at 1000 PSI the tolerances would be a lot tighter. The manufacturer determines what the clearance are for the job the pump is going to do. They will also recommend what the max vacuum on the inlet side should be for best efficiency. This seems to be the best time to explain why some pumps prime faster than others. Since the oil pump inlet line is very short so is the amount of time it takes to start pumping. You can see how close the pump and pickup are by looking at the photos I posted a few days ago. Now that little LP pump is a long way from the fuel tank but that is not a problem if the system doesn't have any air leaks and we have not increased the net positive suction head by adding too many filters, valves, elbows, more line etc. The fuel line from the OEM filter to the inlet side of the LP pump will be full of fuel when we shut down. This is enough fuel to start and run long enough for the LP pump to start drawing through the the check valve in the OEM. The only job the LP pump has to do is supply a constant flow of fuel to the inlet side of the HP pump cylinders to keep them from cavitating. If either pump does not have this steady supply of fuel it will cavitate. Later! Frank


Edited by: Frank Blum

The only job the LP pump has to do is supply a constant flow of fuel to the inlet side of the HP pump cylinders to keep them from cavitating. If either pump does not have this steady supply of fuel it will cavitate. Later! Frank





I hate to say it but this is an incorrect statement. The Low pressure pump not only has to supply a steady flow of fuel but it also must make enough pressure to control the High Pressure comeing from the High pressure pump. Maybe this is where some people are missing how the system works. The Low pressure pump feeds the soloniod which controls the fuel flow and pressure to the high pressure pump. The low pressure holds the high pressure cylinder closed, so when the pressure coming from the low pressure pump drops the high pressure cylinder is allowed to bypass back to the low pressure side. This is how the regulator works.

No! That statement is not incorrect. I thing you understand how this system operates but you don't know how to explain it. I think I can help now because I thing I know what you are trying to say.To start with the pump doesn't pump pressure. It produces flow rated in cubic inches per revolution, GPM, GPH etc. Pressure is the result of the resistance in the system. I thing you are saying that the computer is controlling a solenoid trim valve that bleeds off excess pressure in the HP pump by recirculating it. Am I following you correctly so far? Later! Frank Edited by: Frank Blum

Some info......

The reason the fuel passes under the FICM is to keep the module cool. Then it is drawn through a heater-equipped filter/separator, which has a priming pump and a bleed screw, before reaching the two-stage fuel pump. The spur gears feed the fuel into the high-pressure side of the pump, which is a radial design with three pistons set 120 degrees apart. This camshaft-driven pump only consumes a fraction of the torque necessary to drive a normal injector pump and is capable of producing nearly 30,000 psi of fuel pressure. The pump pressure obviously must be regulated, and for safety purposes, the Bosch folks designed a pop-off valve that feeds excess pressure back into the return side of the system.

The fuel pressure is electronically controlled by the Fuel Rail Pressure Regulator (FRPR). The FRPR is a duty-cycle solenoid mounted in the pump and controlled by the Electronic Control Module (ECM) based on feedback from a sensor in the junction block that provides fuel to the supply rails. The FRPR duty-cycle operates in a 5 to 95 percent window, and unplugging the solenoid drives the fuel pressure to the maximum level instead of vice versa, as we might expect. The ECM increases pulse width to lower pressure, so if the solenoid receives a 100 percent duty-cycle for some reason, pressure will be at its lowest, and performance will obviously degrade. A 5 percent duty-cycle will produce a fuel pressure of 23,200 psi, and a 95 percent duty-cycle feed will produce a 5,000 psi reading. The pressure should never go below 3,000 psi; if it does, something is wrong. The Tech 2 scan tool provides target and actual fuel pressure readings for diagnostic purposes.

A frame-mounted electric fuel pump is used on units with dual tanks, but it doesn't directly provide fuel to the engine. It only transfers fuel from the auxiliary tank to the primary tank when the fuel level gets below a certain level. The ECM controls the relay that drives the pump and monitors the fuel level to determine when the pump should he energized.

On the Power Stroke, the Injection Control Pressure regulator, which is similar but opposite in function to GM/Isuzu's FRPR, operates on a duty-cycle from zero to 65 percent, and oil control pressure drops to zero with the regulator unplugged. If the ICP control wire shorts to ground, the pressure goes as high as 3,750 psi, relieved by a pop-off valve in the high-pressure oil pump. Use common sense safety practices when servicing any diesel system: While maximum control oil pressure on a Power Stroke can reach nearly 4,000 psi, the Duramax fuel system is pressure-relieved at a blistering 27,550 psi. Cracking a fuel line loose on a running Duramax engine could easily be fatal. Don't go there. And don't fool with the Duramax fuel rail bleeder valve unless the engine is at rest and the pressure has been relieved.

THE JUNCTION BLOCK

Fuel is fed from the high-pressure pump to a junction block that sends fuel to the "common rails," which provide controlled fuel pressure to the injectors. The Fuel Rail Pressure (FRP) sensor is mounted in this junction block, along with the mechanically operated pressure relief valve. The sensor is a three-wire design that receives the familiar 5 volts and provides a signal return. If fuel pressure exceeds 27,550 psi, the relief valve unseats and bounces to maintain fuel pressure at that level. Relief pressure is vented into the return system through a line attached to the junction block. Remember, maximum controlled pressure is 23,200 psi, and anything above that should be compared to the scan tool reading of the FRPR pulse width the ECM is providing for detailed analysis.
If the FRP sensor is removed from the junction block for any reason, GM procedures call for replacing the sensor with a new one. The soft iron seat will be deformed the first time the new sensor is torqued, and the old sensor might not seal properly if reused.

COMMON RAILS AND INJECTORS

The common rails are si

NO, the pump feeds to a solenoid which blocks the supply from the low pressure supply, it does not bleed off. Unused fuel being feed to the solenoid is bleed into the interior of the pump and is used for lubrication and returned to the tank through a fixed orifice.The computer controls the flow to the high pressure cylinder as well as the pressure to keep the cylinder closed. Yes, I know pressure is created by volume of fuel being forced into the chamber, that's what I've been trying to tell you for months. Once the solenoid closes no fuel is feed to the high pressure side of the pump assemble and the high pressure begins to fall rapidly! Once it overcomes the pressure holding the cylinder closed it simply pushes fuel from the cylinder up into the upper chamber where it refills the cylinder again on the downward stroke. So the low pressure pump must supply enough volume to create pressure to make the system operate properly. Your statement is incorrect.


By keeping the supply pressure constant the computer is not constantly trying to adjust up and down as the volume of fuel required increases and decreases. When not enough volume is supplied what's the first thing to happen......................... pressure falls. So pressure is an indication of volume in this case.


The ideal lift pump would supply a volume of fuel at a fixed pressure. As the engine required more fuel the volume would increase but the pressure would remain constant. The problem is that in order to supply the volume of a 600 Hp motor you require about 180 GPH. Now add overhead for a regulator to keep fixed pressure and your up to 220 GPH. Now let's drop down to driving the engine at a power output of 75 HP and you only need 30 GPH all that extra volume gets returned to the tank, not good.

more please....................more


so a varible lift pump would be something quite useful. Or, maybe a lift pump regulated to 4 lbs with high volume....er. A pump that supplies a constant 4lbs @ 75HP or 505HP. A pump that will not "fall on it's face" during high RPM and will not "make a river" at idle either.


Am I headded in the right direction? I have spoken at length with Greg about a pump like this.





Burner------------> http://www.dieselplace.com/forum/smileys/Big Smile.gif need more info, please.

Later! Frank Edited by: Frank Blum

Providing pressurized feed to a gear type positive displacement pump can only help to improve the inefficiencies caused by fuel bypassing the gears pure and simple...

Providing pressurized feed to a gear type positive displacement pump can only help to improve the inefficiencies caused by fuel bypassing the gears pure and simple...


In a perfect world this is almost true.


Let's look at how it works, fuel is at the inlet of a gear pump, the gears turn and squeezes the fuel trapped between the teeth and then pushed it out the other side. Pretty basic stuff. Now is there anything that is 100% efficient? Not in this world! So how much of the space between the gears is truly filled with fuel? How much did the pump use up to try and pull the fuel from the tank? Most pumps are rated as one of two types, a puller or a pusher. Typically if it's good at one it bad at the other. So if it pulls (sucks well) it doesn't push well and vice versa.


What does a lift pump do? If the lift pump has a large enough volume it will fill the gear cavity completely @0 psi so we get 100% every time. Now let's increase the pressure............... we now can get 120% into the cavity? So what have we done here with a lift pump? We have increased the volume and pressure of fuel that the Low pressure pump has transfered to the high pressure pump section. The high pressure pump section uses this fuel to fill the cylinder and also to control the high pressure outlet pressure via the computer control. This is where the problem with a non constant fuel pressure comes into play, if it's jumping up and down the computer is constantly chasing a moving target trying to get the high pressure outlet pressure correct!


On a stock engine the inefficiencies of the low pressure pump are not high enough to cause any problems but move the Hp from 300 up to 600 and it is. With the additional fuel requirements we have exceeded what the GM modified fuel system will handle. The original design by Bosch calls out for a lift pump to fill the low pressure pump so why not go back to what the original system was designed for? Does anyone thing that Bosch would have put it in the design if they felt it wasn't necessary? Cummins/Dodge uses the same fuel system, right down to the same low pressure/high pressure pump assemble and it has a lift pump set for 16 - 19 psi...................... that should tell us something.Edited by: Diesel Tech

If dodge is running a lift pump at 16-19 psi, what is the gph in that range with that lift pump???


Who makes the lift pump for the dodge????


What is Boschs recommendation in there book, if they do say the manufacture or does Bosch make there own lift pump????


I can say that with what i'm running(injectors, pcm, edge145) all on the highest settings, i can get my actual rail psi down to 11,000 from demand 22-23,000 http://www.dieselplace.com/forum/smileys/Cry.gif. Not good. I am running a holley red, which will be pulled as soon as i get some concrete info or do some research on whats gonna work. Maybe have to look over a dodge and learn something as this fuel issue is a little baffling to me, as i don't totally understand all of this, especially after reading this thread http://www.dieselplace.com/forum/smileys/Confused.gif. Maybe if i read it another 10 times, it'll sink in http://www.dieselplace.com/forum/smileys/Embarrased.gif

I have no flow data on the Dodge, but I can tell you dropping like you are seeing is just what I've been talking about for over a year now! A Holley will not cut the mustard, event thier Black pump will not handle it. Nick's truck with the Preporator will only drop about 3000 psi from commanded now. Where as before the pump it would drop from a commanded of 23,500 to 10,300 actual! The dodge boys with High Hp are running into the same problem so I know there factory lift pump is not enough. So far I've not found a pump that cures the problem but we are in the process of making one now just to see if we can resolve the issue with the proper size lift pump.

Maybe you guys are missing something. Who says the HP pump is capable no matter how much pressure you feed it. Has anyone shown a high pressure lift pump cures the pressire problem? This may be much more complicated and restrictive than just a lift pump solution.

Hoot





What we know at this point is that a lift pump helps a great deal up to 600 Hp. At that point we begin to see pressure drops again, but we also see fuel supply pressure drops as well. So for the purpose of testing we need to fix the supply problem first. If once that's fixed were still haveing trouble then the answer is pretty simple. I already have a new camshaft being made for the high pressure pump just incasehttp://www.dieselplace.com/forum/smileys/Approve.gif

Hoot, i agree. If/when we get the lift pump all figured out, who's to say the oem hp side isn't a problem as well. Maybe we should be looking at it as well and seeing what its capable of in terms of how much psi it can put out and can it keep up with the demand without dropping major psi. Wouldn't a pressure box help in this situation, some. It would raise rail pressure to higher than stock, and when it drops on a wot then it would still be above what we would have seen without a pressure box, intern giving us more fuel=more power????? Though thats a temporary fix for now, it still should help when the lift pump/factory hp pump gets resolved.


I have been told by a source, so take it for what its worth, that a certain truck was on a dyno and i would assume the pressure box was turned off, that it lost 4000psi rail pressure and it intern lost 200ftlbs. Anyone from California want to chime in on that one http://www.dieselplace.com/forum/smileys/Embarrased.gif http://www.dieselplace.com/forum/smileys/Embarrased.gif and let us know if the strory i was told is true or has it been altered from 5th hand knowledgehttp://www.dieselplace.com/forum/smileys/Geek.gif


Diesel Tech- So what your saying is the prep. still does not cure all ailing symptoms????? A question to Nick or you Steve, what is the prep. set up for as interms of psi and at that psi what gph is it rated for???? By looking back at Nicks dyno run at the LA dyno day, my truck is the exact same, as turns of the bursting.


On edit-I don't know what i'm seeing for drop in psi now, as i have not ran the tech 2 with the injectors and everything installed. Before the injectors i was dropping into the 11,000 mark in actual. Don't know if its more now, or not. Maybe have to get the tech 2 tomorrow and see what she's reading now. I know when shes bursting like that she pours black smoke like no other time http://www.dieselplace.com/forum/smileys/Confused.gif

heartbeat- the prep runs about 7psi at idle, 6 crusing down the freeway at light throttle, and will drop to a lowest setting of about 3psi (give or take a bit) when i do a WOT run with the extreme...

heartbeat- the prep runs about 7psi at idle, 6 crusing down the freeway at light throttle, and will drop to a lowest setting of about 3psi (give or take a bit) when i do a WOT run with the extreme...


Do you know what the gph is, at 7psi?????? and 3 psi????


My holley red was set at 7psi, at idle. In a wot run it would drop to 4-4.5 psi, before injects. I know at 7psi i'm flowing about 92 gph.Edited by: heartbeatcanada

Adding a pressure box is no good, all you do is run out sooner. The Preporator took the bursting on Nick's truck from 2800 Rpm up to 3800 before it burst now. This allowed me to change the tuning some but not much and it gain over 200 ft/lbs. At idle we have about 7 psi and at full power were down to 2.5 - 3.0 psi on the supply. What's funny is there is no difference whether it's on the dyno or run on the street, we get the same thing. All the self proclaimed hydraulic expert's said it would be less on the street. I guess just some good old fashion work showed how much they knew.


If you've installed larger injectors think about what you've done......... larger holes allows more fuel in the cylinder faster. The supply has not changed so the problem just occurs sooner than before. We have a fixed volume of fuel to use and there ain't no more. Once it's gone it's gone. I don't know what the outcome will be but all I can do is the testing and fix the problems as we find them. Once we solve the supply issue we will see where that gets us. Like I said before I've already got a new camshaft being made for the HP pump, I figure it should give us about a 16% increase in capacity from the HP pump.

What is Nicks actual dropping to above 3800rpm????


I realize that what i was running before the injectors, probably will not work now. Kind of like a stack, your not getting full potential out of one of the modules/pcms/tuners and i'm demanding alot more fuel.


I have to solve my fuel issue before i can start seeing what works and what doesn't at the track or on the dyno. I know that when i run the 135 quad with the 90 edge there is no bursting, but my 1/4 mile time is lower. I then tried the 215 quad with the 145 edge and no bursting, and i picked up 1/2 second in the 1/4 mile. Same goes for the pcm i am playing with, i can have edge on the 145 and no bursting. All this is with no nos, as i want to get my #2 dialed in first, then play with the nos. In all runs wth no bursting, i still get a hiccup for a second then it comes back and settles down, but is obviously hurting my e.t..


I know of a couple of guys running at 12-14 psi and 140gph and aren't having problems that i know of. It seems there is a big variance in what guys are running as psi and gph, guess it all depends on what programming they're using.

Hoot, i agree. If/when we get the lift pump all figured out, who's to say the oem hp side isn't a problem as well. Maybe we should be looking at it as well and seeing what its capable of in terms of how much psi it can put out and can it keep up with the demand without dropping major psi. Wouldn't a pressure box help in this situation, some. It would raise rail pressure to higher than stock, and when it drops on a wot then it would still be above what we would have seen without a pressure box, intern giving us more fuel=more power????? Though thats a temporary fix for now, it still should help when the lift pump/factory hp pump gets resolved.


I have been told by a source, so take it for what its worth, that a certain truck was on a dyno and i would assume the pressure box was turned off, that it lost 4000psi rail pressure and it intern lost 200ftlbs. Anyone from California want to chime in on that one http://www.dieselplace.com/forum/smileys/Embarrased.gif http://www.dieselplace.com/forum/smileys/Embarrased.gif and let us know if the strory i was told is true or has it been altered from 5th hand knowledgehttp://www.dieselplace.com/forum/smileys/Geek.gif


Diesel Tech- So what your saying is the prep. still does not cure all ailing symptoms????? A question to Nick or you Steve, what is the prep. set up for as interms of psi and at that psi what gph is it rated for???? By looking back at Nicks dyno run at the LA dyno day, my truck is the exact same, as turns of the bursting.


On edit-I don't know what i'm seeing for drop in psi now, as i have not ran the tech 2 with the injectors and everything installed. Before the injectors i was dropping into the 11,000 mark in actual. Don't know if its more now, or not. Maybe have to get the tech 2 tomorrow and see what she's reading now. I know when shes bursting like that she pours black smoke like no other time http://www.dieselplace.com/forum/smileys/Confused.gif





Seems like Diesel Tech has been doing some R&D for a few months now on the factory HP pump. Shhhhhhh! Don't tell anybody. Some of you think he's http://www.dieselplace.com/forum/smileys/Wacko.gif .


The pressure box only seemed to make my truck worse when it was starved for fuel. I could feel it lay down without the pressure box, turn up the box, it would lay down and then bursting would occur. Remember there has to be volume to create pressure.


On this last dyno go round (TTS EXTREME) we saw the FASS start at 7 psi and slowly drop to 5 psi. over a 20 second run. Does that make it better than the Prep? Nope, it's just o

[QUOTE=heartbeatcanada]


Hoot, i agree. If/when we get the lift pump all figured out, who's to say the oem hp side isn't a problem as well. Maybe we should be looking at it as well and seeing what its capable of in terms of how much psi it can put out and can it keep up with the demand without dropping major psi. Wouldn't a pressure box help in this situation, some. It would raise rail pressure to higher than stock, and when it drops on a wot then it would still be above what we would have seen without a pressure box, intern giving us more fuel=more power????? Though thats a temporary fix for now, it still should help when the lift pump/factory hp pump gets resolved.


I have been told by a source, so take it for what its worth, that a certain truck was on a dyno and i would assume the pressure box was turned off, that it lost 4000psi rail pressure and it intern lost 200ftlbs. Anyone from California want to chime in on that one http://www.dieselplace.com/forum/smileys/Embarrased.gif http://www.dieselplace.com/forum/smileys/Embarrased.gif and let us know if the strory i was told is true or has it been altered from 5th hand knowledgehttp://www.dieselplace.com/forum/smileys/Geek.gif


Diesel Tech- So what your saying is the prep. still does not cure all ailing symptoms????? A question to Nick or you Steve, what is the prep. set up for as interms of psi and at that psi what gph is it rated for???? By looking back at Nicks dyno run at the LA dyno day, my truck is the exact same, as turns of the bursting.


On edit-I don't know what i'm seeing for drop in psi now, as i have not ran the tech 2 with the injectors and everything installed. Before the injectors i was dropping into the 11,000 mark in actual. Don't know if its more now, or not. Maybe have to get the tech 2 tomorrow and see what she's reading now. I know when shes bursting like that she pours black smoke like no other time http://www.dieselplace.com/forum/smileys/Confused.gif





Seems like Diesel Tech has been doing some R&D for a few months now on the factory HP pump. Shhhhhhh! Don't tell anybody. Some of you think he's http://www.dieselplace.com/forum/smileys/Wacko.gif .


The pressure box only seemed to make my truck worse when it was starved for fuel. I could feel it lay down without the pressure box, turn up the box, it would lay down and then bursting would occur. Remember there has to be volume to create pressure.


On this last dyno go round (TTS EXTREME) we saw the FASS start at 7 psi and slowly drop to 5 psi. over a 20 second run. Does that make it better than the Prep? Nope, it's just one more piece of data to consider. Your results may vary. http://www.dieselplace.com/forum/smileys/Cool.gif


Dropping to 11,000 psi at WOT! <IMG id='chkImg1' name='chkImg2' id=chkImg1 onmouseover="this.style.cursor='hand'" onmouseout="this.style.cursor=''" alt="Click on image to open in new window" src="smileys/Shocked.gif" border=0 name=chkImg2 border="0"

Two things......... we only ran Nick's truck to 3600 RPM and watched the pressure and it was down to 2.5 - 3.0 psi. I believe the Preporator is 160 Gph but I don't have any real proof that's what it is. You need to check with Preporator to get the numbers. What pump are your friends running that is 140 Gph? None of the Holley's (red blue silver or black)are that high. The Black is the largest and it's rate at 140 Gph @ 0 psi. That one would not hold any pressure at full power when we did testing so I know the Preporator and FASS flow more than the Holley.


Two, the amount of fuel being delivered has everything to do with it. Run stock up to 400 Hp and there will be little of any problems with no lift pump. Get up to 600 Hp on #2 and it's a whole new ballgame.

One is a Carter, and the other is a Mallory, 140 i believe. These 2 trucks are around the 500hp mark on #2. From what they've told me they are having no problems. They both seem to be right at the 12-14 psi set presssure and running right around 140gph. If i remember correctly the mallory is hardly dropping in psi in a wot situation, not sure about the carter.


I also talked to Brad, i think that was his name, from FASS at Muncie and he said that around the 14psi mark is what they seem to be running on the dmaxs. At that psi its running 144gph. At that point when i talked to him, i thought it was a consencis(sp) that a pump would have to be 12-14 psi and flow 140 gph, as that was 3 votes for the higher psi, and gph.


Now during this thread i see some guys running at 7psi and seem to be doing somehwat fine. Maybe the higher psi and 140 gph would work bettter than what they are currently running, or has been discussed on here, i don't know. It seems there is a variety of guys with different experiences, some seem to be working, some aren't working ,and some are getting by.


Diesel Tech, not sure about your second statement on the last posthttp://www.dieselplace.com/forum/smileys/Confused.gif I agree, just not sure who its directed at http://www.dieselplace.com/forum/smileys/Ermm.gif or where it came from. Maybe i've been out in the sun too long today http://www.dieselplace.com/forum/smileys/Embarrased.gif

AFAIK the fass and prep both use the same motor and gear rotor. obviously there are some internal differences, but i would GUESS the output would be pretty similar..


heartbeat - i don't know the GPH, and i haven't been able to run a snapshot at the strip as i left my tech2 at home. i'll run it on my local testing road next week and see where it goes.. bear in mind my truck has seemed to have been one of the worst for output of the stock fuel system - ie it needs more help than others http://www.dieselplace.com/forum/smileys/Cry.gif

Dodge runs a stock Carter 4601. They last about 50,000 to 80,000 miles and puke. They have 14psi energized with engine off, 11psi at idle, and 2 to 4.5psi WOT stock. 20,000 miles will cut those numbers in half. Stacked with a frame mounted Holley black body (12-802), the numbers are 24psi energized, 21.5psi idle, 15.5 psi WOT up to 550hp on the ground. The Holley needs serviced once to every three Carter replacements. Starving the VP44 for fuel kills the rotor at the distributor head, being lubed by fuel (or the lack there-of). Starving or cavitating the HP pump on these should have the same affect on the pistons and bore in the HP pump. I'd much rather over fuel and bypass than churn and pump iron. I'll monitor this post for a while, but when HP building starts, I'll probably try the Holley 12-706. Quieter, rebuildable, can be bought anywhere. I also noticed on the "other" board that Kennedy already has a successful kit for these, and no-one has had probs with function or install, so that's a good one to watch also. BTW, real glad to have found this site. I new there had to be a bunch of guys playing hard with these trucks that had to be in the know. Thanks guys...T

AFAIK the fass and prep both use the same motor and gear rotor. obviously there are some internal differences, but i would GUESS the output would be pretty similar..


heartbeat - i don't know the GPH, and i haven't been able to run a snapshot at the strip as i left my tech2 at home. i'll run it on my local testing road next week and see where it goes.. bear in mind my truck has seemed to have been one of the worst for output of the stock fuel system - ie it needs more help than others http://www.dieselplace.com/forum/smileys/Cry.gif





If you get a ticket on the local testing road, just send the infraction to Mac, he's a vetern at all that stuff.http://www.dieselplace.com/forum/smileys/HiHi.gif


I would also assume the fass and prep. would be somewhat close to outputs.


My trucks seems to be having a tougher time with certain programming than my buds with his 03. But then he runs something that my truck likes, and he has problems. Its tough to know which direction to turn when both trucks act so differently. Either way its a fuel issue and probably what fixes one will fix the other, at least that's what we hope.

Dodge runs a stock Carter 4601. They last about 50,000 to 80,000 miles and puke. They have 14psi energized with engine off, 11psi at idle, and 2 to 4.5psi WOT stock. 20,000 miles will cut those numbers in half. Stacked with a frame mounted Holley black body (12-802), the numbers are 24psi energized, 21.5psi idle, 15.5 psi WOT up to 550hp on the ground. The Holley needs serviced once to every three Carter replacements. Starving the VP44 for fuel kills the rotor at the distributor head, being lubed by fuel (or the lack there-of). Starving or cavitating the HP pump on these should have the same affect on the pistons and bore in the HP pump. I'd much rather over fuel and bypass than churn and pump iron. I'll monitor this post for a while, but when HP building starts, I'll probably try the Holley 12-706. Quieter, rebuildable, can be bought anywhere. I also noticed on the "other" board that Kennedy already has a successful kit for these, and no-one has had probs with function or install, so that's a good one to watch also. BTW, real glad to have found this site. I new there had to be a bunch of guys playing hard with these trucks that had to be in the know. Thanks guys...T





Welcome aboard, and what a great first post. You answered some of my earlier questions. I agree that if we are starving our hp pumps, what toll is it taking on it. I'm gonna assume its gonna get "tired" faster and not do its job properly or to its full potential. Probably there is alot of "us" out there with this situation.


Take for example, i used to be able to run the 135 quad and 145 edge stack last year with no driveability problems. Now 3 months ago, i tried it again and its a no go. I had injectors issues, and thought it could have been excess return flow that was causing my lack of flow to the injectors. I did have at least 2 injectors that were buggered, and of coarse at this time i opted to get JKS injectors put in.


Point being, it used to work and before my truck got the injectors put in it wouldn't. That to me means there has to be something wrong with another component, or as i said just getting "tired"


Probably when we get the lift pump issue solved, then the hp pump should last longer and maybe we won't have many problems, but until then, i think thats gonna be the next outbreak of problems, at least the guys running high horsepower for a while with no lift pump or a lift pump not up to par. Thats my thoughts, but am i in no way an expert or have as much knowledge as some on here. http://www.dieselplace.com/forum/smileys/Big Smile.gif

My reply got lost so reposted.Edited by: Kennedy

The FASS or Preporator will not make anything over 8 psi on a Duramax. Believe me we have tried, Sdaver and Trippin are running the FASS and Nick is running the Preporator. Sdaver tried to raise the pressure on the FASS with no luck. It would raise at idle but as soon as we made Hp it dropped right back to where it was before at about 4 psi. I sure wish it would have worked as I really do not have the time to make a pump but you got to do what you got to do. The Dodge VP44 is not a common rail system if I remember correctly, Ynot please correct me if I'm wrong on this one as I do not do alot of dodge work.


My comment on 600 Hp was not directed to anyone, it's just a big difference when you get to the numbers were making now on #2 only on the Duramax with just a program. Few people have ventured in this area and the few that have, haven't run these numbers very long. What I mean is how long will things hold before dropping off and what is causeing them to drop. At this point in time I believe it's a fuel problem and that's what I've been chaseing for a year. Each time we think it's fixed something else jumps into the picture. Once we get to the end of the road I know we will have a great fuel supply system but will that solve it? I do not know. Have you replaced the fuel pickup in the tank yet? If not you need too. Believe me once you get the stock one out it will scare you. Nick's truck has it done and a few others have either done it or are getting ready to put them in. Trippin can sell you the parts for it if you do not want to make them like we did.

What about running two pumps in parallel. One pump can run off the ignition, and the other pump could be manually turned on for WOT runs. This way, the stock return line would not have to ever return large amounts of fuel back to the tank.

[QUOTE=Kennedy]Providing pressurized feed to a gear type positive displacement pump can only help to improve the inefficiencies caused by fuel bypassing the gears pure and simple...


In a perfect world this is almost true.


Let's look at how it works, fuel is at the inlet of a gear pump, the gears turn and squeezes the fuel trapped between the teeth and then pushed it out the other side. Pretty basic stuff. Now is there anything that is 100% efficient? Not in this world! So how much of the space between the gears is truly filled with fuel? How much did the pump use up to try and pull the fuel from the tank? Most pumps are rated as one of two types, a puller or a pusher. Typically if it's good at one it bad at the other. So if it pulls (sucks well) it doesn't push well and vice versa.


What does a lift pump do? If the lift pump has





Just my thoughts....and I could be wrong......The following could be the ramblings of a lunatic http://www.dieselplace.com/forum/smileys/Wacko.gif..... but...... Lets talk about getting fuel from the tank to the HP pump. Any type of flow is based on pressure, orifice and time. (Time comes later, lets stick to pressure and orifice for now).


For a given dia. of fuel line, lets say 5/16, 5 psi will push a given quantity of fuel from the tank to the HP pump. 10 psi will push even more.


Now because I don't want to change all the fuel lines in my truck, and because a 1.7 sec 60ft time is about 1.3G of acceleration, I say run as much pressure as the EDU can take. http://www.dieselplace.com/forum/smileys/Big Smile.gif


Lets talk about the HP pump, we are pushing fuel to the HP pump from the tank at say 5 psi, every time the HP pump takes a drink of fuel we would like it to have it's cavity 100% full. I think 100% efficiency is possible if we fill it to the brim each time it takes a drink. Remember, fluid doesn't compress very well so all we can hope for is to fill it 100%. Now we have everybody's enemy, TIME. We only have a certain amount of time to fill the HP pump each cycle. Given that we know 10 psi is going to move more fuel through a given orifice than 5psi, I say run as much pressure as the EDU can take. http://www.dieselplace.com/forum/smileys/Big Smile.gif


Now if there is clearance in the HP pump that lets fuel run through it in a static situation which way will it go in a dynamic situation? Certainly not to the high side that's for sure. But if we keep some postive pressure on it, at least there will be less of a leak, that is to say we have just increased the efficiency of our pump. I say run as much pressure as the EDU can take. http://dieselplace.com/forum/smileys/Big%20Smile.gif


<FONT color=#ff00

Who's with me...........


Repeat after me..."Run as much.........http://www.dieselplace.com/forum/smileys/Big%20Smile.gif


Run as much as the EDU can take.


I don't think anyone has disagreed with this, but no one knows how much the EDU can take. I think the last I heard, the 5psi test was complete, and so far the 10psi test is looking good but not complete. Correct me if I'm wrong.

Who's with me...........


Repeat after me..."Run as much.........http://www.dieselplace.com/forum/smileys/Big%20Smile.gif


Run as much as the EDU can take.


I don't think anyone has disagreed with this, but no one knows how much the EDU can take. I think the last I heard, the 5psi test was complete, and so far the 10psi test is looking good but not complete. Correct me if I'm wrong.





Kennedy has said over and over again it's not needed and does no good! The pump is a positive displacement pump and pressure will do no good. I believe he is flat out wrong and our testing has been proving that!


Bottom line is we are trying to make the fuel system do soooooo much more than it was designed for. I do not have all the answers that's for sure but let's solve the problems as we can and see how much better we can make it, instead of crying it's no good, it will not work.

So what is the edu testing up to now, diesel tech?????

If you all spent half as much time working as you do on the internet we probably would have figured this out by now http://www.dieselplace.com/forum/smileys/Big Smile.gif


Unfortunately there is always a catch to every pump i have discovered. Either it doesnt like diesel fuel, cant handle the elements of daily use, is extremely loud, or just costs and arm and a leg. Havent quiet found one that covers all these aspects but some of us are working on it. And like Steve said, the pickup is equally as important as the supply pump. Doesnt matter what pump you put inline, if you havent modified the pickup you are bound to have delivery problems or overheat the pump. Hopefully by late next week we can confirm all Steves predictions.

Have you replaced the fuel pickup in the tank yet? If not you need too. Believe me once you get the stock one out it will scare you. Nick's truck has it done and a few others have either done it or are getting ready to put them in. Trippin can sell you the parts for it if you do not want to make them like we did.





I met Steve and Nick at the LA dyno day in Feb. Here is something Steve designed during that meeting. I like to have fun with CNC machining and CAD systems so I whipped a few up. They have been out in the field being tested and so far so good. On the quest to improve the fuel system it seemed logical to start in the tank. I think making the negative pressure side as unrestictive as possible so the lift pump can get everything it needs is the first step. Additonal photos, and of higher resolution can be found on my web site.


http://www.dieselplace.com/forum/uploads/EAE_108_0888a.JPG

I'm not smart enough http://www.dieselplace.com/forum/smileys/Cry.gif to be able to load two photos in the same post so here is another.


http://www.dieselplace.com/forum/uploads/DFF_108_0892a.JPG

The initial run was 9 pcs. Those are all in the field for testing. I started getting more and more requests from people that heard from someone that someone heard that someone had them. http://www.dieselplace.com/forum/smileys/HiHi.gif So I made up about 30 more.


I have formed an LLC to sell these under, called Southern California Diesel. Or So Cal Diesel for short. The whole liability thing scares me. They will be offered at $95.00 ea.


You will need to modify your sending unit to accept the larger hose. I milled and drilled the example shown to use a -10 AN line bulkhead with socketless connectors and then plumb it to your lift pump. You can purchase the fittings from any AN supply house for about $35.00 including the hose. Some creative people have used copper fittings for their install but I thought the AN was cool! http://www.dieselplace.com/forum/smileys/Cool.gif


I originally thought about offering exchange sending units already modified, but using someone elses core/exchange was risky. Sooner or later somone would end up with an inoperable gas gauge. And I think the new sending units are approx. $400. Maybe one of you techs can get a better price. I will modify your sending unit if you want to send them to me. The cost to modify will be $50.00 and I can turn them around usually in one day, barring earthquakes! http://www.dieselplace.com/forum/smileys/HiHi.gif


Guys, I do have a real job and this is basically just a service I will provide on the side. I'm sure my employer would not appreciate any personal phone calls at work. So PM me here if your interested. Steve didn't think there would be enough interest to offer them through TTS or that someone else would just rip off the design and copy it right away. So that's how I ended up offering them to you guys.


The 2001-2003 sending units need to be modified. The 2004 looks like it will me much easier to do, but we haven't completed that install yet.

Thanks Trippin! Why is there no check valve in the system? Is it not included so that pump can show fatigue in morning starts? Would it not help the pump on a stock truck?


Burner----------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif

To elaborate on what trippin' said, here is mine- been in for a couple months. Handywork by Mr. TTS.. Click for a larger version. That is for 5/8 hose.


http://www.wackywack.com/images/dmax/pickup1_sm.jpg (http://www.wackywack.com/images/dmax/pickup1.jpg) http://www.wackywack.com/images/dmax/pickup2_sm.jpg (http://www.wackywack.com/images/dmax/pickup2.jpg)Edited by: Diesel Power

Thanks Trippin! Why is there no check valve in the system? Is it not included so that pump can show fatigue in morning starts? Would it not help the pump on a stock truck?


Burner----------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif





Uh....the stock one does not have one so I didn't include one either......good question for a GM Engineer. IMHO a check valve could provide a restriction in the system which is what I was trying to eliminate with this pick up. Food for thought, my truck sits on an angled driveway every night approx. 10 degrees nose up and never had a problem starting. A very good question though.

Providing pressurized feed to a gear type positive displacement pump can only help to improve the inefficiencies caused by fuel bypassing the gears pure and simple...


In a perfect world this is almost true.


Let's look at how it works, fuel is at the inlet of a gear pump, the gears turn and squeezes the fuel trapped between the teeth and then pushed it out the other side. Pretty basic stuff. Now is there anything that is 100% efficient? Not in this world! So how much of the space between the gears is truly filled with fuel? How much did the pump use up to try and pull the fuel from the tank? Most pumps are rated as one of two types, a puller or a pusher. Typically if it's good at one it bad at the other. So if it pulls (sucks well) it doesn't push well and vice versa.


What does a lift pump do? If the lift pump has a large enough volume it will fill the gear cavity completely @0 psi so we get 100% every time. Now let's increase the pressure............... we now can get 120% into the cavity? So what have we done here with a lift pump? We have increased the volume and pressure of fuel that the Low pressure pump has transfered to the high pressure pump section. The high pressure pump section uses this fuel to fill the cylinder and also to control the high pressure outlet pressure via the computer control. This is where the problem with a non constant fuel pressure comes into play, if it's jumping up and down the computer is constantly chasing a moving target trying to get the high pressure outlet pressure correct!


On a stock engine the inefficiencies of the low pressure pump are not high enough to cause any problems but move the Hp from 300 up to 600 and it is. With the additional fuel requirements we have exceeded what the GM modified fuel system will handle. The original design by Bosch calls out for a lift pump to fill the low pressure pump so why not go back to what the original system was designed for? Does anyone thing that Bosch would have put it in the design if they felt it wasn't necessary? Cummins/Dodge uses the same fuel system, right down to the same low pressure/high pressure pump assemble and it has a lift pump set for 16 - 19 psi...................... that should tell us something.








How do you get 120% into the cavity? Someone correct me if I'm wrong, but last I checked, fluids do not compress...





I've never said that a lift pump was not a good idea, or not beneficial. I am of the position that we can do no more that eliminate the inefficiencies (gear clearances) of the OE transfer pump.





Having a constant feed to the injection pump DOES help the computer's duty cycle decisions easier, as well as keeping the fuel from vaporizing in the lines. I think the truck runs smoother and responds better.





CT dyno day. Dipper put down top numbers. Lift pump?


Mac had 2nd place numbers. Lift pump?





As for inertial vs. staic loads, a lot depends on if a regulator is used, and where the regulator is placed.


I don't have a regulator, so all of the load is placed on the pump(s) directly...

I also talked to Brad, i think that was his name, from FASS at Muncie and he said that around the 14psi mark is what they seem to be running on the dmaxs. At that psi its running 144gph. At that point when i talked to him, i thought it was a consencis(sp) that a pump would have to be 12-14 psi and flow 140 gph, as that was 3 votes for the higher psi, and gph.


Now during this thread i see some guys running at 7psi and seem to be doing somehwat fine. Maybe the higher psi and 140 gph would work bettter than what they are currently running, or has been discussed on here, i don't know. It seems there is a variety of guys with different experiences, some seem to be working, some aren't working ,and some are getting by.


Diesel Tech, not sure about your second statement on the last posthttp://www.dieselplace.com/forum/smileys/Confused.gif I agree, just not sure who its directed at http://www.dieselplace.com/forum/smileys/Ermm.gif or where it came from. Maybe i've been out in the sun too long today http://www.dieselplace.com/forum/smileys/Embarrased.gif








If the FASS pump produces 144gph at 14 psi which we are told it cannot even achieve, what does it free flow?


I'd like to see the flow curve for this "monster" pump. I think you'll find the performance claim to be far overstated. Could be wrong but...





Typically pumps are rated at psi and at gph, but do not achieve max flow at rated psi.





Mallory Comp 140 curve is on Page 10:


http://mrgasket.com/pdf/mal_fuel.pdf

I say run as much pressure as the EDU can take. http://dieselplace.com/forum/smileys/Big%20Smile.gif


Who's with me...........


Repeat after me...."Run as much.........http://www.dieselplace.com/forum/smileys/Big Smile.gif











Go for it! Actually, I think the limitation will be the RPCV. I've seen the system pressurized to a point where the rail psi could not be managed at idle. No EDU failures.





Still waiting for someone to show me the massive loss of HP we must be sustaining. Again, NOT against lift pumps, they are a GOOD thing, just haven't seen anybody come along and show big HP gains by adding. Tomac has made how many 12 second passes without?





As for the Dodge HPCR, it is same but different. Word is, they dry thiers up with a moderate box already. There is a DISTINCT difference in the operation of the HPCR pump on the Cummins as I am told... Edited by: Kennedy

[QUOTE=Burner]





Thanks Trippin! Why is there no check valve in the system? Is it not included so that pump can show fatigue in morning starts? Would it not help the pump on a stock truck?


Burner----------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif








Flow checking is done in the OE filter head by a pair of flimsy rubber valves with extremely soft seating springs.


Uh....the stock one does not have one so I didn't include one either......good question for a GM Engineer. IMHO a check valve could provide a restriction in the system which is what I was trying to eliminate with this pick up. Food for thought, my truck sits on an angled driveway every night approx. 10 degrees nose up and never had a problem starting. A very good question though.Edited by: Kennedy

While I'm not against adding a lift pump, on the track my truck has not shown any gains with one. However, my rail pressure is only dropping about 2500-3000 psi with the lift pump instead of about 4500-5000 psi without.

BTW, I always run with a 1/4 tank of fuel. I've also tried running with 1/2, 3/4, full tank but the truck doesn't run any better/faster so I figure the weight of the extra fuel isn't worth it. Edited by: mtomac

While I'm not against adding a lift pump, on the track my truck has not shown any gains with one. However, my rail pressure is only dropping about 2500-3000 psi with the lift pump instead of about 4500-5000 psi without.

BTW, I always run with a 1/4 tank of fuel. I've also tried running with 1/2, 3/4, full tank but the truck doesn't run any better/faster so I figure the weight of the extra fuel isn't worth it.


Mtomac, was there a drag race/pulling option on the order form for our trucks when you bought yours? http://www.dieselplace.com/forum/smileys/Big Smile.gif


Your truck does all the right stuff! I wish I could get mine to be the same. http://www.dieselplace.com/forum/smileys/Thumbs Up.gif


Your either extremely lucky or extremely innovative. Either way your still my Dmax hero. http://www.dieselplace.com/forum/smileys/Cool.gif Keep it up! Your a racing machine and I look forward to reading each one of your new conquests!

Has any of the dyno kings on here set up a fuel cell w/ dual pumps(or triples) w/ a filter on each pump line then go direct to dmax pump.


Eliminate all the stock stuff and see what happens when u have the max flow.


BTW does anyone have a flow meter in-line, Grainger has them for $100.





Someone at Muncie had a small tank in the bed and he has a few horsepower.

In reference to the Cummins, I had the first 24V (ISB) with the VP44. I haven't messed with the new HPCR motor. The stock Carter T-pump was junk, and I've stacked T-pumps in series on my last 4 work trucks with no probs. Have yet to find a need for #10 supply line, drilled banjo bolts, dual pumps parallelled, etc.. Tho the end result seems to be keeping rail pressure up in the mid 20's thru the "extended" power band, the original idea was to always have positive pressure in the system, eliminating cavitation and starving. The internals will last a lot longer with higher than normal pressures than they will running dry with no lube. I've had the best luck with 20+psi into all the systems (6.5GM, 7.3IH, 7.3 Hypermax turbo, Cummins ISB). Pumps and injectors last longer and the power is much more consistant and reliable, not to mention the added bennies of "key on" system priming and bleeding. Looks like the first thing to monitor is line and rail pressure under demand situations and upgrades. I suppose dash mounted 40psi and 25,000psi fluid gauges are the ticket, but finding taps and routing the heavy line should s#&amp;k. I'll try the Holley 12-706 with no other mods first. Claimed output is 250GPH at 15psi. Sounds close to required numbers, with the added suction of the LP pump. Cavity pressure at the inlet of the pump should be in the low 20's. I won't settle for any drop at the rail. No other engine I know of will drop pressure at the injector under load. If anything, it needs to increase. I don't have any motor mods yet, so this will be a good time to start the game and monitor progress (or the lack thereof) and numbers. Thanks guys...T

Tony,


Have you run the 12-706 before? Looks like a good solution, yet Holley's web site says "not designed for continuous use." Of course what they recommend and we do are two seperate things. http://www.dieselplace.com/forum/smileys/Big Smile.gif It's not like the manufacturer recommends our trucks for racing!


If the pump does fail, we need a way to bypass fuel in order to keep the truck running.

CT dyno day. Dipper put down top numbers. Lift pump?


Mac had 2nd place numbers. Lift pump?








Not that it matters but if we look at Net gain RWHP on fuel we know who really had the greater gain in RWHP ....Everyone looks at Gross numbers ....


Wa !!!


Yes I have a lil baby Pump looking HP AirDog, maybe ....I'd be willing to do some before after testing on a Superflow if anyone would like to push some funding Eastbound ....





Mac http://www.dieselplace.com/forum/smileys/Tongue.gifEdited by: Mackin

Tony, what are you going to try the holley on, a dmax, or cummins? Sorry if you stated before but i can't find if your running a dmax or cummins, as they both seem to have a somewhat similar hpcr system.


Kennedy, thats what i'm worried about, you talk to someone about there product and they tell you one thing, and then you see guys on here can't achieve what i was told it is capable of. I'd be extremely upset paying that much for the fass and it not producing what i was told. Thanks for the mallory link, will spend some time looking it over. Seems to work for a certain truck putting down some quick times and nice numbers on the rollers. http://www.dieselplace.com/forum/smileys/Big Smile.gif Think since he's done an install allready, he'd want to do mine, since his is so neat and tidy. http://www.dieselplace.com/forum/smileys/Embarrased.gif


Let me think outloud here. If say a guy were to put the fass or prep. system in there truck, whats stopping him from removing the oem filter and bypassing it totally??? Could there be some flow restriction in the oem filter that is hindering us as well. I know warranty would be out the window, or you could just bypass it when at the track and turn it back on for day to day driving http://www.dieselplace.com/forum/smileys/Geek.gif These are just thoughts that are gong threw my head right now. If i was to go to the trouble of starting in the tank, and make bigger lines and have a better filtration set-up than stock, why not bypass the oem filter and continue with bigger lines all the way. Or am i just wackedhttp://www.dieselplace.com/forum/smileys/Confused.gif http://www.dieselplace.com/forum/smileys/Wacko.gif

Trippin why wouldn't u use the big holley pump paralell w/ a smaller continous duty pump and use the it manually or w/ a pressure switch to use for the few times u need it.


A check valve in line would stop the back flow w/ the big pump off.

CT dyno day. Dipper put down top numbers. Lift pump?


Mac had 2nd place numbers. Lift pump?





Not that it matters but if we look at Net gain RWHP on fuel we know who really had the greater gain in RWHP ....Everyone looks at Gross numbers ....





greater gain.......gheesh......always something....http://www.dieselplace.com/forum/smileys/Clap.gif


Works both ways though....if your saying it's possible that you got more from the same.....then you have to look at it like this....with a lift pump...I'll be that much higher...http://dieselplace.com/forum/smileys/Embarrased.gif


I can't remember for sure, but I think my baseline was only 3hp higher than yours.

Kennedy said


"How do you get 120% into the cavity? Someone correct me if I'm wrong, but last I checked, fluids do not compress..."


I guess I didn't not word my post properly before


"What does a lift pump do? If the lift pump has a large enough volume it will fill the gear cavity completely @0 psi so we get 100% every time. Now let's increase the pressure............... we now can get 120% into the cavity? "


I thought the ? at the end would get people thinking, I guess I should have said 120% more than we are currently getting into the low pressure pump cavity stock. I think Trippin did a better job at explaining it than I did but the concept is one in the same. Yes, I know fluids do not compress.


Let's talk some proven facts:


There have been several post by different people who have reported gains from 10 - 35 Hp by adding a lift pump, just go back and search for them JK.


There have been several post of people feeling an increase in performance and smoothness with out dynoing after lift pump install.


The TTS Xtreme program is making more Torque and Hp than any other program on the market, I guess that's why we run into these problems first!


Let's go back a year ago when I started telling people about a problem with the fuel system Mr.Kennedy was the first to say I was crazy and there were no problems with it .................. So Mr. Kennedy is now changing his position, again.


Let's talk about the dyno days, Makin has a lift pump although it's too small and I believe Big Dipper has added one but I'm not sure, they both had good runs and both were running TTS programs!


Off my soap box now

Trippin why wouldn't u use the big holley pump paralell w/ a smaller continous duty pump and use the it manually or w/ a pressure switch to use for the few times u need it.


A check valve in line would stop the back flow w/ the big pump off.





I asked this question a page up, and no one answered. I think it would be the best of both worlds.

Let me think outloud here. If say a guy were to put the fass or prep. system in there truck, whats stopping him from removing the oem filter and bypassing it totally??? Could there be some flow restriction in the oem filter that is hindering us as well. I know warranty would be out the window, or you could just bypass it when at the track and turn it back on for day to day driving http://www.dieselplace.com/forum/smileys/Geek.gif These are just thoughts that are gong threw my head right now. If i was to go to the trouble of starting in the tank, and make bigger lines and have a better filtration set-up than stock, why not bypass the oem filter and continue with bigger lines all the way. Or am i just wackedhttp://www.dieselplace.com/forum/smileys/Confused.gif http://www.dieselplace.com/forum/smileys/Wacko.gif





I started a whole thread on this a while back. Here is the link:


http://dieselplace.com/forum/forum_posts.asp?TID=6549&amp;KW=Amric

&lt;snip&gt;


Let's talk about the dyno days, Makin has a lift pump although it's too small and I believe Big Dipper has added one but I'm not sure, they both had good runs and both were running TTS programs!


Off my soap box now





http://dieselplace.com/forum/forum_posts.asp?TID=10492&amp;PN=1&amp;TPN=1





Mac http://www.dieselplace.com/forum/smileys/Approve.gif

Amric


Yes, you could run two pumps if setup properly. I never though finding a single pump that would me our needs would be so tough. I just donot like putting more and more things in as it seems the more there is, the more that fails when you do not need it too. Every time I think we have found a pump that will work a few phone calls to the manufacture and we are right back where we started.............. still looking. The Holleys will not do it and when I called Mallory about the 250 series I was told race only and they were not sure how well it would handle diesel fuel. The FASS and Preporator work well but still come up short on the high Hp applications.

I would think there might be some type of electric transfer pump on agriculture or construction equipment that might work-dont know really, just an idea.

DT, I sold the Dodge and went GMC for the Allison. I'll update my sig and add on as things change. I don't think there's a light duty made that doesn't need a fuel boost when things are "up to spec". I really don't think it's quite this complicated either. TDR made a nightmare of the whole supply thing, and I just quit emphasizing the fix is as easy as feeding the motor thru an add-on electric. You can crunch all the numbers in the world, making all kinds of formula's to theorize a desired result, trying account for bends, 90's, extra or higher micron filtration, G force, etc., but the best test is always the real test. Bolt it up, check the gauges, and run the &amp;%$# out of it. As for the longevity of the 706, I really don't know, and have never used one, but they draw 1/2 the amps of the 815, run in diesel instead of gas (providing viscous lube), and have the advantage of suction at the outlet from the LP pump. I think it'll work fine, but I'll let you know either way. I really think that they're all pretty much the same anyway. All of the light duties in our class have about the same CID's, end up with about the same HP and torque on the ground, and blow about the same unburnt fuel out the stack. That said, the only real variable is the bypass in the system. If we control what is sent back to the tank unused, they all will take about the same fuel to give the desired numbers on the ground. There are guys getting good numbers with little or no boost to the fuel system, so any increase is to the positive. Just get the best t-pump you can afford and check your psi's. If they go up, you succeeded, plain and simple. Every little bit helps, especially when it's a PM thing...T

Trippin why wouldn't u use the big holley pump paralell w/ a smaller continous duty pump and use the it manually or w/ a pressure switch to use for the few times u need it.


A check valve in line would stop the back flow w/ the big pump off.





Dmax Tim, Thats' another good solution!

Tony, what are you going to try the holley on, a dmax, or cummins? Sorry if you stated before but i can't find if your running a dmax or cummins, as they both seem to have a somewhat similar hpcr system.


Kennedy, thats what i'm worried about, you talk to someone about there product and they tell you one thing, and then you see guys on here can't achieve what i was told it is capable of. I'd be extremely upset paying that much for the fass and it not producing what i was told. Thanks for the mallory link, will spend some time looking it over. Seems to work for a certain truck putting down some quick times and nice numbers on the rollers. http://www.dieselplace.com/forum/smileys/Big Smile.gif Think since he's done an install allready, he'd want to do mine, since his is so neat and tidy. http://www.dieselplace.com/forum/smileys/Embarrased.gif


Let me think outloud here. If say a guy were to put the fass or prep. system in there truck, whats stopping him from removing the oem filter and bypassing it totally??? Could there be some flow restriction in the oem filter that is hindering us as well. I know warranty would be out the window, or you could just bypass it when at the track and turn it back on for day to day driving http://www.dieselplace.com/forum/smileys/Geek.gif These are just thoughts that are gong threw my head right now. If i was to go to the trouble of starting in the tank, and make bigger lines and have a better filtration set-up than stock, why not bypass the oem filter and continue with bigger lines all the way. Or am i just wackedhttp://www.dieselplace.com/forum/smileys/Confused.gif http://www.dieselplace.com/forum/smileys/Wacko.gif





It's a long drive for the install appointment! http://www.dieselplace.com/forum/smileys/Big Smile.gif There are definitely some creative solutions being engineered for these problems. Some things work, some don't. I don't think that there is a silver bullet in one component of this system.


There does seem to be no shortage of controversy on this subject though.

I would think there might be some type of electric transfer pump on agriculture or construction equipment that might work-dont know really, just an idea.


This may be the ticket, any canditates?


I kinda like the idea of just give it more pressure(up to what is safe).


I think I've decided to bit the bullet. Its time to find a pump.....maybe agg or heavy equipment.


I didnt ever doubt if a lift pump would help, I was just curious about why it did.http://dieselplace.com/forum/smileys/Geek.gif

Kennedy said


"How do you get 120% into the cavity? Someone correct me if I'm wrong, but last I checked, fluids do not compress..."


I guess I didn't not word my post properly before


"What does a lift pump do? If the lift pump has a large enough volume it will fill the gear cavity completely @0 psi so we get 100% every time. Now let's increase the pressure............... we now can get 120% into the cavity? "


I thought the ? at the end would get people thinking, I guess I should have said 120% more than we are currently getting into the low pressure pump cavity stock. I think Trippin did a better job at explaining it than I did but the concept is one in the same. Yes, I know fluids do not compress.


Let's talk some proven facts:


There have been several post by different people who have reported gains from 10 - 35 Hp by adding a lift pump, just go back and search for them JK.


There have been several post of people feeling an increase in performance and smoothness with out dynoing after lift pump install.


The TTS Xtreme program is making more Torque and Hp than any other program on the market, I guess that's why we run into these problems first!


Let's go back a year ago when I started telling people about a problem with the fuel system Mr.Kennedy was the first to say I was crazy and there were no problems with it .................. So Mr. Kennedy is now changing his position, again.


Let's talk about the dyno days, Makin has a lift pump although it's too small and I believe Big Dipper has added one but I'm not sure, they both had good runs and both were running TTS programs!


Off my soap box now








So we are back to my original statement that adding a lift pump can only make up for the the inefficiencies of the gear type transfer pump, AND keep our fuel in fluid form. No increase in delivery beynod what the gears will move at 100% efficiency.





I still have not seen one instance of quantifiable data where someone has performed multiple tests before and after installing a lift pump in an even remotely stable environment...





I've been running a lift pump on my truck for quite a long time now. Longer than most, I'd hazard to guess. Part of the lift pump craze started with the TST Comp module and the nasty "bursting" that occurred with it. This bursting however, occurred with or without fuel lift.





As I understand, Dipper did not have a lift pump, AND was running a stacked combo as was Mackin (Dipper = TTS 120 and Mackin = TTS Extreme both stacked with Edge as I understand) when their max numbers were achieved. Maybe Mackin's lift pump helped him. Maybe it hurt him. Only way to know is to test... Edited by: Kennedy

How traveled news gets miss represented ..... http://www.dieselplace.com/forum/smileys/Wink.gif

Me and the Dipper were running the same stack ...... Whether or not we had Identical "race " programs we'll never know ....
When your in a shoot out ,we aint playing target practice .... http://www.dieselplace.com/forum/smileys/Embarrased.gif



Mac http://www.dieselplace.com/forum/smileys/Geek.gif

Big Dipper wrote..........





"Van Aaken and the TTS Extreme were each within a few for highest single box hp numbers for the day.....the highest torque was the TTS Extreme......"


Think that about sums it up.

Pardon my lack of knowledge but what is "bursting". With the modified pickup, do you use a #10 line from the pickup to your "primary" filtration and from there a #10 line to the lift/pusher pump. And from there on utilize the OEM lines? What are the pro's in the DHRA running? What else besides GM/DODGE use the HPCR fuel system? Is this technology developed solely for the "light" duty market or is it in use in the heavier market?

Pardon my lack of knowledge but what is "bursting". With the modified pickup, do you use a #10 line from the pickup to your "primary" filtration and from there a #10 line to the lift/pusher pump. And from there on utilize the OEM lines? What are the pro's in the DHRA running? What else besides GM/DODGE use the HPCR fuel system? Is this technology developed solely for the "light" duty market or is it in use in the heavier market?


Because of the low pressure involved, we want to make it as easy as possible for the lift pump to get an adequate supply of fuel. Hence the -10 line. I would go from the pickup to the lift pump, then through the filter.


IMHO "Bursting" is a term used to describe the lean misfire that occurs due to lack of fuel being supplied to the engine.

Wouldn't it be better for the LP to have filtered fuel through it?

Ok, I have some ideas, but may be way off base here. Please let me know what you think. With a lift pump, you are trying to keep a constant supply of fuel to the HP pump. You keep mentioning lift pump psi, but why? If you run a small 3/8" hose to the HP pump you will have plenty of pressure but not enough volume. Why not run a very high quality high volume pump such as a Barry Grant BG400 or BG280. Run it with 3/4" (12AN?) line to the HP pump inlet, use either a bypass type regulator or a bypass type pump. The PSI doesn't really matter, it will have a TON of volume. If you still cannot maintain HP pressures then it would seem to indicate a bottleneck elsewhere, perhaps the HP pump itself or as mentioned the filtration system.


In any case, a good supply of fuel to the HP side shouldn't be as difficult to obtain as it seems to be. Am I missing something, or I am I really way off base here?

Thomas all a good plan ...


Running a fuel line (rubber) all that distance and across the motor bypassing the EDU would only be a test purpose only ....


I would believe we need to use the OE supply lines in order to get something into real life usage IMO ...





Mac

That bring up another question. If the fuel running through the electronics is a bottleneck, how about running a low pressure pump seperately just for that purpose?

Wouldn't it be better for the LP to have filtered fuel through it?





Yes that would be the best plan for diesel fuel ....


Most pumps are designed to push not pull thru a media device ....


The Preporator Airdog and Fass and Strandyne are the only ones that I'm aware of the incorporate such filtering ... None have pr oven yet to keep Rail pressure from falling off but are still with in Bosch spec of acceptable PSI drop ...


The debate continues ....


Mac http://www.dieselplace.com/forum/smileys/Approve.gif

Wouldn't it be better for the LP to have filtered fuel through it?





For longevity of the pump, absolutely! For minimum restriction and performance, nope. I looked at the pictures I had of the FASS and it may actually run the fuel through the 1st filter/water seperator before the pump, but I couldn't be sure. I called and am waiting for a return call.


FYI, in most car oiling systems the pump draws up the oil from the sump and then sends it to your oil filter under pressure and then to the engine. Not really the same thing we were talking about but it was what I pictured in my head when I first answered your question. Of course consistently refueling our trucks opens up the possibility for far more debris to enter the system than an oiling system ever would see.

What we are seeing with current lift pumps is the pressure in the feed pump line falls at the same time the Hp in the rail falls. This is what has led us down this road to begin with. We are trying to locate a lift pump that will not drop pressure and see if that intern solves the High pressure problem. To date that goal has not been meet. I suppose we could remove all the line and replace with larger but if the pump will not stay up it doesn't much matter. If the restriction was the lines we would not see the pressure drop at the pump outlet and the HP inlet at the same time and that's what we currently see. As far as BG pumps I was told they are not for continuous duty so that ruled them out in our testing. The trick is how much time do we have to fill each gear cavity as it spins by. At low engine speeds it's much easier but as the fuel demand goes up and engine speed increases you have less time to fill and more required fuel needed, so pressure is the answer to the filling problem............ get more in, in a shorter time frame.

That bring up another question. If the fuel running through the electronics is a bottleneck, how about running a low pressure pump seperately just for that purpose?


Real world complication and reversibility for dealer service for the fuel system while under warranty if needed ....Not to sure a simple T would do it as fluid will take the path of least restriction ...





Mac

Any way to enlarge the orifice to each gear cavity? Is the inlet smooth? In other words, can it be "ported" to allow more fuel to enter in a given time?

By the way, all good stuff. I'm certainly no expert, but I do appreciate all your answers. It helps me think, and lets me know what the experts think about any given situation.

Ok, I have some ideas, but may be way off base here. Please let me know what you think. With a lift pump, you are trying to keep a constant supply of fuel to the HP pump. You keep mentioning lift pump psi, but why? If you run a small 3/8" hose to the HP pump you will have plenty of pressure but not enough volume. Why not run a very high quality high volume pump such as a Barry Grant BG400 or BG280. Run it with 3/4" (12AN?) line to the HP pump inlet, use either a bypass type regulator or a bypass type pump. The PSI doesn't really matter, it will have a TON of volume. If you still cannot maintain HP pressures then it would seem to indicate a bottleneck elsewhere, perhaps the HP pump itself or as mentioned the filtration system.


In any case, a good supply of fuel to the HP side shouldn't be as difficult to obtain as it seems to be. Am I missing something, or I am I really way off base here?








This is exactly where i am headed, i think. I spent last night looking at Barrry Grant, and Magnaflow pumps. Came to the conclusion that i'm going big or not doing it all. Start in the tank with a bigger pick up, to an aftermarket filter, to a Barry Grant pump(example), to a bypass regulator, and to the oem pump, bypassing the oem filter. All lines fron the tank to the oem pump will be either 10an or 12an line. This should solve all my fuel feed issues, and if there is problems with rail pressure after this, then its on to the hp pump.


Am i off my rocker.....maybe..... or maybe i'm just alittle extreme and want the most out of this beast, come hell or high water i'll get'r done. Edited by: heartbeatcanada

heartbeatcanada http://www.dieselplace.com/forum/smileys/Clap.gif


Another pump brand you may want to look at is Aeromotive. I think they also manufacture under the name SX. They specialize in inline high pressure fuel injection pumps, but I think they used to have a low pressure high volume inline pump for carburated applications.


I wish you the best luck!

To test the theory without buying more fuel pumps, you could suspend a fuel can with large dia fuel hose above the engine at various heights over the dyno for different continuous pressures:


Roughly 3ft per PSI you want to test at.


But to test at 14PSI you'll need to hang it from a telephone pole... http://www.dieselplace.com/forum/smileys/Confused.gif





Edited by: McRat

heartbeatcanada http://www.dieselplace.com/forum/smileys/Clap.gif


Another pump brand you may want to look at is Aeromotive. I think they also manufacture under the name SX. They specialize in inline high pressure fuel injection pumps, but I think they used to have a low pressure high volume inline pump for carburated applications.


I wish you the best luck!








Thanks for the other manufacture. The way i look at it is BG and the other pumps i am looking at are for extreme hp in race application. They flow huge volume, which we need, as long as it does not drop off drastically when the hp demands more. I don't think these race pumps will have a problem as thats what they are built for. Expensive, yes, but if it works then to me its worth it. True they are not for constant duty, but i'll address that when i sit down to design my system. Its not going to be quick, nor do i want to rush any of my decisions as i want this done right. Might cost some $$$$ with a BG pump or such and an aftermarket filter setup, but at least i'll know its up to snuff and then it'll be on to the next fix or massaging of oem parts.


As far as warranty concerns, thats not a concern to me for what i want out of this truck. Anybody who knows me personally knows how extreme and warped and twisted i am with power, and i will/don't stop until every last bit of power is squeezed out of the 6.6. Spare motor is on standby and if its not used this summer, it will be tore apart this winter, and lets just say it will be freshened up. http://www.dieselplace.com/forum/smileys/Big Smile.gif

You keep mentioning lift pump psi, but why? If you run a small 3/8" hose to the HP pump you will have plenty of pressure but not enough volume.





I think we are all on the same page of thinking. There are 2 ways to move more fluid. Increase the line thats carying it or increase the pressure. PSI is just how much restriction there is to flow. You could have 80psi and have 0 flow.


I think alot of us are asking because we are wondering what the problem is in the first place mostly outa curiosity.


Most of us also would prefer to keep the stock fuel line and cram more psi down its throat if it will accomplish the same thing. If its fixing a LP pump problem or what ever we just want results with minimum fuss. Its much easier to stick a big lift pump on there then to possibly fix the actual problem if it is a LP pump or even just smaller lines or what ever its problem is.


One thing I was wondering but have since kinda droped that relates to PSI is if there was a set PSI that was needed for a particular HP level. But all the truck seem to respond differently...... It would be realy easy if you could say to make x HP you need to have x psi at this location, then you would just need to do some calcs to figure out what pump would suit your needs. But I dont think a consensus will be reached on that since trucks seem to be much more picky and I doubt the fuel systems are clsoe enough between trucks to draw some generalizations. And most people go with the bigger is better approach instead of figuring out the exact amount of fuel they need to flow. So it may be very hard to figure out flow needed to support a specific HP level based on PSI.


Maybe we just need to do some testing as was brought up. Run seperate fuel cell and a big honking BG pump. See what we see if there is any drop pressure or hp wise.......Edited by: ratlover

Well, it kinda sucks but if one were to go with a race pump with a shorter life expectancy and put a bypass around it and it were to die you would still not be stranded. Granted you couldnt be out runing WFO spraying but you could limp around for a bit till you rebuilt the thing. Witch brings up another point.....most race type pumps are rebuildable.

http://www.bgfuel.com/bgfuel/default.aspx?page=44


Hmmmmm, looks promising.

The bypass is very easy to plan ahead for and should be done. Takes me all of a few minutes to be back in business if the pump goes south......

http://www.bgfuel.com/bgfuel/default.aspx?page=44


Hmmmmm, looks promising.





I like this part the best


"Internal bypass, requires no return line to the fuel tank"

By the way, all good stuff. I'm certainly no expert, but I do appreciate all your answers. It helps me think, and lets me know what the experts think about any given situation.


It's a team effort, glad to have your participation!

I wonder............ is there a difference between vacume when running #10 or #12 line vs. the OEM stuff? Has anyone tested this?





Burner------------&gt;

http://www.bgfuel.com/bgfuel/default.aspx?page=44


Hmmmmm, looks promising.





Dejavu(sp). Eaxactly what i was looking at last night, plus others from BG.

Less restriction with bigger line so i would say less vacume.


They say factory limited at 18psi. I have an email into em, it still may require a bypass to the tank. We shall see what they say.

Yup, BG had some other interesting stuff but whan I saw that one.....


1000pph or 400pph. Any idea what kinda HP this would support? That may get to be a hard question to aswer too though.....same lines as the PSI.....

I like where this is headed http://www.dieselplace.com/forum/smileys/Clap.gif

Well, it kinda sucks but if one were to go with a race pump with a shorter life expectancy and put a bypass around it and it were to die you would still not be stranded. Granted you couldnt be out runing WFO spraying but you could limp around for a bit till you rebuilt the thing. Witch brings up another point.....most race type pumps are rebuildable.


That is really quite easy .... Mine is done that way with a Ball Valve to dictate flow direction ..


Mac

Mackin, make sure the orifice in the ball valve is not so small that it becomes a restriction.

Mackin, make sure the orifice in the ball valve is not so small that it becomes a restriction.


Like half inch ,Uh huh ...





Mac http://www.dieselplace.com/forum/smileys/Approve.gif

Hey Mackin,


Was "orifice size" a topic of discussion at Centerfolds the other night?

















I meant regarding the fuel system! http://www.dieselplace.com/forum/smileys/Embarrased.gif

someone said it before. Have two lift pumps, One like a lot of us have now, and one "race" ,The ones that are not ment for continuous use.


If the race pumps do the trick, then it is real easy to have two lift pumps and with a flip of a switch, standard lift pump is turned off and race pump is on for the 1/4mi or 300 feet or dyno run. Check valves, or solenoids after each pump so when one is running other is not effected. walla, so why not test the "race" pumps????
And sure, have a bypass also, the plumbing would not be that damn complicated.


We have to test, since the data is not there for diesel fuel applications. I would be on it if I had a better financial situation.


Kyle

Wouldn't it be better for the LP to have filtered fuel through it?





For longevity of the pump, absolutely! For minimum restriction and performance, nope. I looked at the pictures I had of the FASS and it may actually run the fuel through the 1st filter/water seperator before the pump, but I couldn't be sure. I called and am waiting for a return call.


FYI, in most car oiling systems the pump draws up the oil from the sump and then sends it to your oil filter under pressure and then to the engine. Not really the same thing we were talking about but it was what I pictured in my head when I first answered your question. Of course consistently refueling our trucks opens up the possibility for far more debris to enter the system than an oiling system ever would see.





I got confirmation, that the FASS runs the fuel through the first filter/water seperator then to the pump.

Here's something to naw at ....





The fuel pressure is electronically controlled by the Fuel Rail Pressure Regulator (FRPR). The FRPR is a duty-cycle solenoid mounted in the pump and controlled by the Electronic Control Module (ECM) based on feedback from a sensor in the junction block that provides fuel to the supply rails. The FRPR duty-cycle operates in a 5 to 95 percent window, and unplugging the solenoid drives the fuel pressure to the maximum level instead of vice versa, as we might expect. The ECM increases pulse width to lower pressure, so if the solenoid receives a 100 percent duty-cycle for some reason, pressure will be at its lowest, and performance will obviously degrade. A 5 percent duty-cycle will produce a fuel pressure of 23,200 psi, and a 95 percent duty-cycle feed will produce a 5,000 psi reading. The pressure should never go below 3,000 psi; if it does, something is wrong. The Tech 2 scan tool provides target and actual fuel pressure readings for diagnostic purposes.





If the FRPR is commanded to 95 Percent duty -cycle what good would it do to shove more fuel at it ??


I had a very interesting conversation with Eric our Dyno operator a week ago ...


Mac http://www.dieselplace.com/forum/smileys/Confused.gif

If the FRPR is commanded to 95 Percent duty -cycle what good would it do to shove more fuel at it ??


Mac http://www.dieselplace.com/forum/smileys/Confused.gif





When the regulator is at 100% that is fully closed and there will be no fuel pressure other than what leaks by. At 95% your at the limit in the program for setting the lowest pressure so you don't need any more fuel at that point. The problem we see is 5% (software limit)and low High pressure! So what can we do to help? By feeding more to the HP pump the pressure rises and the ECM see it then the regulator responds by changing the duty cycle. So if we feed it too much it just cuts it back. What we need to be careful with is that we don't feed it so much it cannot regulate at low fuel consumption points.

For you guys thinkin on twin pumps and the like, I made a quick and easy "demand" feed design for a 1200hp Cat. You'll have to regroup on the lines, but I T'd off the T-pump, ran a second #10 feed line to the bottom of the tank, put a 12-815 behind the T, and fired it thru a 35lb. pressure switch in the manifold with a relay. 44psi idle, 34psi at 30psi boost, and 48psi at 40psi boost. No switches... On the Holley vane pumps, you can draw thru them when it's off and only lose 1psi per 10psi inline (I suppose depending on demand. This was on the Dodge). I wish I had time to throw the Holley on this week, but I'm booked solid. I know it's not this difficult. This same thread went thru the TDR for years with thousands of posts, but this fix for the do-it-yourselfers ended up being a 20 minute job with one pump and 3' of 3/8" fuel hose. Give the whole system a 10lb. pressure boost (or whatever), and the end (i.e. rail) pressures were more than adequate. It's already got two pumps. Just give them a little help...T

Multipule fule pumps would work fine I'm sure and plumbing wouldnt be the problem, like you said it wouldnt be that hard. I just have the problem with droping all the cash for 2 pumps if I could get one to do the job.


Macking, nice auto deal and a good idea. Will it be evident though if it dies and start going into bypass mode? Other than really floging it....


My kinda sucks coment was directed at the fact that it would be much nicer to have a pump last quite awhile than one that had a 200hr life expectancy and having to rebuild it all the time and have some downtime. With a bypass(witch I will run regardless) it atleast wont strand ya.....


I dont think that high of PSi is a good idea??? So it kinda hinders you to find a pump that will put out what you need at a lower PSI. I think most dont think the holley vane pumps are the ticket??? Still trying to decide on a lift pump.


Ive been trying to figure out this whole lift pump thing for quite some time since I dont want to run additional filtration without a lift and I dont want to run one lift and then have to scrap it for a different unit once I turn up the wick. Yes guys, I just have the factory fuel filterhttp://www.dieselplace.com/forum/smileys/Embarrased.gif

has anyone tested any of the "primary/secondary" filtration that is being added to the trucks to see what kind of loss they have. If we are putting 2 filters (OEM+ 1) after the LP, that is going to give some kind of loss in PSI. Might be minimal but I am just wonder if one flows better than another of equal micron rating.

I just got off the phone with a few suppliers and it looks like we may have a solution in the works, finally. One of our suppliers can build the pump assemble to supply the necessary fuel capacity and we are going to build the electronics to control it for them. This pump will have a variable output so it solves the low speed fuel requirement and high speed requirement It has a key on primp feature built in and a safety shut down. This is a on demand system. So the pump will produce as little as 50 GPH and, when commanded, it will produce 220 GPH. Everyone is in place and starting on the project. It will take a few months to get the prototypes up and running. Stay tuned.

Anyone that thinks they will be able to add a lift pump so the hp pump can instantly achieve desired psi is crazy. Stretching the pulse width and adding larger injectors and such strains every component in the fuel system to or past their limits. No matter how much fuel you stuff to your engine anyone over 500 hp is out of air unless the have a upgraded turbo. Most 500 hp (except trucks with different turbo's) trucks I have seen will continue to smoke at wot which proves your leaving hp at the table.

Kinda' off topic.......... has anyone noticed that their MPG went "UP" after a lift install?


Burner---------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif

Anyone that thinks they will be able to add a lift pump so the hp pump can instantly achieve desired psi is crazy. Stretching the pulse width and adding larger injectors and such strains every component in the fuel system to or past their limits. No matter how much fuel you stuff to your engine anyone over 500 hp is out of air unless the have a upgraded turbo. Most 500 hp (except trucks with different turbo's) trucks I have seen will continue to smoke at wot which proves your leaving hp at the table.


What? What are you trying to say here, CPMac? http://www.dieselplace.com/forum/smileys/Confused.gif

Anyone that thinks they will be able to add a lift pump so the hp pump can instantly achieve desired psi is crazy. Stretching the pulse width and adding larger injectors and such strains every component in the fuel system to or past their limits. No matter how much fuel you stuff to your engine anyone over 500 hp is out of air unless the have a upgraded turbo. Most 500 hp (except trucks with different turbo's) trucks I have seen will continue to smoke at wot which proves your leaving hp at the table.


Well its sure not going to hurt if that IS the case. Don't know if you've seen Nicks dyno vid. with his truck bursting, but his truck was going down to actual rail pressure of 10,500 from what i've read here. He put a prep. pump in and its solved up to a certain rpm.


I have the same symptoms other than mine drops to 11,000 actual rail pressure. That to me means one of two things......its either there isn't enough fuel on the lp side to feed the hp side(lift pump fix), or the factroy pump is not big enough or cannot handle what its being demanded to do. Maybe its both, only time will tell.


If Bosch originally designed this system with a lift pump, which the hpcr cummins has now and followed Boschs recommendations that to me means a lift pump is a must. I'm not going to doubt Boschs designs.


I totally agree that we need more air, no doubt about that. But if we can't get to the 500hp on # 2 without bursting or hesitations on a wot run then that turbo or nos does us no good, until the problem is solved. Seems some trucks are not having problems and some are having little quirks and others are having major bursting, maybe its due to different programming use, or maybe its just the hp pump is tired on some trucks from being starved for fuel for quite some time. http://www.dieselplace.com/forum/smileys/Embarrased.gifEdited by: heartbeatcanada

In a Nut shell


There can not be a pump to fuel instant desired demand ....


We are at our limit of HP of 500 ish without additional air supply whether by bottle or turbo ... There is plenty of fuel available presently in stock form ....





Stretching the pulse width (that's when you sence the bucking) beyond the FRPV duty cycle won't help pushing low pressure fuel at the inlet side ....Therefore we're limited right where we're at ....


In addition if you get on the bottle and or add a bigger hairdryer to burn up the exsisting unburnt fuel dumping out the tailpipe already ....


There ....


Mac http://www.dieselplace.com/forum/smileys/Geek.gif


On Edit


OOOPS HBC snuck in GrassHopper ...Edited by: Mackin

OOOPS HBC snuck in GrassHopper ...





Whats That Suppose To Mean?????

I've had my and a customers dyno to 470RWHP with my big VA, and 490'5 stacked. No lift pump.





BMDMAX has had a modified (my cobble job)pickup, and Mallory Comp pump with a bypass regulator installed for some time. Still at low 500's stacked, and no verifiable gain.





I still believe a lift pump is a very good thing to have on any Dmax. Not so much for the max flow, but so that the fuel supply is as steady as possible so that the ECM can make the proper decisions in RPCV duty cycle and modulate pressures in a much smoother fashion...Edited by: Kennedy

OOOPS HBC snuck in GrassHopper ...





Whats That Suppose To Mean?????





That my post was to be right after yours ....


Gheeeeesh do people seem a little touchy or is it me ....





Mac http://www.dieselplace.com/forum/smileys/Ermm.gif

My Bad, sorry Machttp://www.dieselplace.com/forum/smileys/Embarrased.gif

Nobody has replied about my thought on porting the inlets to the HP pump. Are they smooth, can they be deburred, chamfered, etc to slightly increase flow? Can they be enlarged somewhat to increase flow? Would you want to do this, and why?


Would porting on the exhaust (and intake) ports help flow to the point of allowing more air in and out? Would a hotter camshaft benefit the volume of air in and out? Can the turbine housing be ported? If so, how bad is it? (does it have a lot of casting flash, or is there a lot of material that can be removed to benefit flow?)


Can the exhaust feed tubes to the turbo be slightly enlarged diameter wise to allow more airflow? Can the exhaust manifolds be ported? Would the exhaust manifolds benefit from extrude honing?


There is SO much that we haven't explored yet. The true potential of the Duramax has not been reached, although at some point upgrades will be necessary (better rods, rod bolts, crankshaft, oiling issues, etc etc)

Prime example of this discussion in real life .... From the Boys on the TDR ....Take a peek ...


http://csramotorsports.com/videos/diesel1.wmv





That is some funny stuff and they are having some fun with it and I can't blame them ....





Mac http://www.dieselplace.com/forum/smileys/HiHi.gifEdited by: Mackin

I've had my and a customers dyno to 470RWHP with my big VA, and 490'5 stacked. No lift pump.





BMDMAX has had a modified (my cobble job)pickup, and Mallory Comp pump with a bypass regulator installed for some time. Still at low 500's stacked, and no verifiable gain.





I still believe a lift pump is a very good thing to have on any Dmax. Not so much for the max flow, but so that the fuel supply is as steady as possible so that the ECM can make the proper decisions in RPCV duty cycle and modulate pressures in a much smoother fashion...





While your pickup mods are not as pretty as the ones Trippin has machined (nice work BTW!) we did gain a significant increase in flow. The stock intake is pretty much a POS.


I would put my lower fuel system up against anyone else's right now and it has gained me NAFT on the dyno as Mac would say.

Prime example of this discussion in real life .... From the Boys on the TDR ....Take a peek ...


http://csramotorsports.com/videos/diesel1.wmv





That is some funny stuff and they are having some fun with it and I can't blame them ....





Mac http://www.dieselplace.com/forum/smileys/HiHi.gif








Mac, thats what i'm talking about, but from inside driving my truck i would have to say mine looks or feels alittle more violent than that ........could be wrong, but its totally wrong on the inside let me tell you, makes me want to http://www.dieselplace.com/forum/smileys/Throw Up.gif


Theres the symptoms, now whats the fix????


1. lift pump???? what manufacture??? what psi??? what gph????


2. massaged hp pump????


3. both???

I've had my and a customers dyno to 470RWHP with my big VA, and 490'5 stacked. No lift pump.





BMDMAX has had a modified (my cobble job)pickup, and Mallory Comp pump with a bypass regulator installed for some time. Still at low 500's stacked, and no verifiable gain.





I still believe a lift pump is a very good thing to have on any Dmax. Not so much for the max flow, but so that the fuel supply is as steady as possible so that the ECM can make the proper decisions in RPCV duty cycle and modulate pressures in a much smoother fashion...





While your pickup mods are not as pretty as the ones Trippin has machined (nice work BTW!) we did gain a significant increase in flow. The stock intake is pretty much a POS.


I would put my lower fuel system up against anyone else's right now and it has gained me NAFT on the dyno as Mac would say.





What about the upper????http://www.dieselplace.com/forum/smileys/Wink.gif

A good truck won't tell all her secrets.... http://www.dieselplace.com/forum/smileys/Wink.gif


That video is what you get when you stack the new Quad 215 Version 1.20 with the HJAT 145 in level 5. That is a programming problem, not a fuel delivery burst per se. I think that is timing causing a problem more than anything.


That same truck with the old Quad 215 and HJAT 145 stack runs 12.5 with N20 on the stock fuel system so I don't think he has a fuel delivery problem.


Oh, and I would expect nothing less from the TDR. Shows real class making fun of a guy that is trying different things to go faster. http://www.dieselplace.com/forum/smileys/Disapprove.gif Some work, some don't.Edited by: BMDMAX

A good truck won't tell all her secrets.... http://www.dieselplace.com/forum/smileys/Wink.gif


That video is what you get when you stack the new Quad 215 Version 1.20 with the HJAT 145 in level 5. That is a programming problem, not a fuel delivery burst per se. I think that is timing causing a problem more than anything.


That same truck with the old Quad 215 and HJAT 145 stack runs 12.5 with N20 on the stock fuel system so I don't think he has a fuel delivery problem.


Oh, and I would expect nothing less from the TDR. Shows real class making fun of a guy that is trying different things to go faster. http://www.dieselplace.com/forum/smileys/Disapprove.gif Some work, some don't.





Thats weird as i have just a small hiccup with the new 215 and 145 stack, and of coarse injectors. I have that bursting problem when i run the 135 and 145. My pcm stack has a small hiccup as well. The small hiccup or burst i know isn't a problem to fix, but the 135 stack is more than a lift pump can cure thats for sure.


I wouldn't be concerned about all the different programs, but i'm trying to see what works the best with the injectors. Obviously full balls to wall stack before probably isn't going to yield the best results, now with injectors into the equation. Seat of the pants feel, is the one with the major bursting, at least up until that point or at highway speeds. Edited by: heartbeatcanada

That problem in IMO cannot be corrected as it goes beyond the capabilities of our system ....


Just like the TST Comp did a Big Va box and a certain stack I can do also and a few other combo's avail ... I thought I busted the drivetrain right out of my truck the other day .... I was rolling into the throttle ,tach dropped and came back up with a vengeance and heavily barked them meats out back .... Scary to say the least ....


Whether the TDR (dodge) guys are poking fun or not there having the same problem so I hear ,no one has captured it on film yet ...


I did get a PM from someone ,he will be vindicated of not getting his truck to perform ,,,http://www.dieselplace.com/forum/smileys/Wink.gif


Mac

I really don't want to come off as though I am bashing Steve but I have said over and over that I don't believe their is a pump made (Practical) that will totally offset LP pump pressure fluctuations. What are we trying to accomplish here anyway. I also feel at this time time that the fluctuating rail pressures engineered into our system for optimum fuel delivery for varying conditions is above the turn down rates (Max Flow Rate) of the INJECTOR itself anyway. Stock HPCR pump &amp; injectors are sized for these stock trucks and will only take you so far. I would be all out surprised if installing a high volume lift pump to maintain peak rail pressure would equate to more HP. It will however slightly increase the duration at which the HP pump and injectors see higher pressures when not needed and therefore result in a possible increase in NEEDLESS wear to the pump, injectors and FRP regulator. The term critical flow often used in my line of work simply means that once you reach the flow capacity of a given orifice you simply will not move more through it by increasing or maintaining pressures above the threshold of that given orifice design.(Our Injectors) You have simply reached the max thruput built into this orifice design (size). Thats why most of these boxes gain the majority of their HP from pulse width instead of pressure. While I do maintain my opinion of the reasonable benefits of a lift pump I feel it has it's limitations as to what can be accomplished with one. Overcoming inefficiencies of the LP pump, maintaining fuel in solution, possible protection from cavitation, more efficient filter utilization and easier starting come to mind as a few of the positive reasons one might consider the lift pump. If someone crossed the performance box stage and truely wants to build a race engine it would be more measurable to take it beyond fuel delivery from the tank to the LP pump. Get past the monster lift pump and get over it! Simply maintaining pos. pressure should be all that is needed for the above common benefits.


This kind of reminds me of the days when young kids put a Holly carb on their engine with a glass pack muffler and thought they had something. http://www.dieselplace.com/forum/smileys/Wink.gif Edited by: a bear

That video is what you get when you stack the new Quad 215 Version 1.20 with the HJAT 145 in level 5. That is a programming problem, not a fuel delivery burst per se. I think that is timing causing a problem more than anything.





Brandon, I respect your opinion and I don't mean to appear contradictory but....FYI, My truck with the same stack V1.20 and HJAT 145 does the exact same thing as the video. Unless of course my tank is more than 1/2 full, then she runs all the way through the 1/4. Programming or fuel delivery? I don't know. Just my observations. I just chose to chase fuel delivery, cuz I personally can do something about that in the privacy of my own garage. http://www.dieselplace.com/forum/smileys/Big Smile.gif Less than 1/2 full, I'm working under the "slosh hypothesis". Launch truck, fuel slosh uncovers pick up canister, truck hesitates fuel runs forward, pump takes drink, truck launches again, fuel runs to the back uncovers pick up canister, truck hesitates, repeat as needed until common sense takes over and you lift.Edited by: Trippin

The term critical flow often used in my line of work simply means that once you reach the flow capacity of a given orifice you simply will not move more through it by increasing or maintaining pressures above the threshold of that given orifice design. You have simply reached the max thruput built into this orifice design (size).



Exactly! Pressure vs orifice! Now lets assume .312 ID line...I'm guessing here, but assuming somewhere in our fuel system we are moving through a .312 or maybe even smaller orifice. What is the positive pressure that causes critical flow to occur, (assuming a straight line .312 orifice system) and what is the flow in GPH based on a specific gravity of.......oh I don't know, lets just say .86

There are so many Variables .... One of the Extremes I'm trying will lightly burst on a DynoJet but not on a Superflow ...


Also will Burst with Attitude set on "0" divorce the Juice and wa la run like a scalded dog ...


Many many variables ....


What also is very interesting is how not one single ECM program will put the number down that a stack will ... So definately power can be made with the exsisting fuel system but no doubt it has it's limitations ...


Mac

If the HP pump has a solid cam and piston design, can't you bore the housing and lathe out bigger pistons? As for porting, EVERYTHING HELPS. I gained 38hp, from 528 to 562, porting the last one (head, exhaust man., intake man., turbine housing, jake brake housing, etc). I don't think it was so much the material removed (bore increase) as it was smoothing out the castings for turbulance. Gained 3psi boost also, up to 51psi, which is where the needle stopped on the gauge... How are ya'll reading rail pressure? Thru the ECM or external gauge?? Thanks...T

Any engineers or rocket scientists want to try and determine the length of fuel line in feet from the tank to the LP side of the fuel pump.


Then determine the ID of the line and figure out the maximum amount of liquid (Diesel ) that can be pulled or pushed through it.


If the VOLUME of the line is so small that the amount of liquid that can flow through it has a theoretical limit even under pressure, then any size pump GPH will do us no good in theory.


I asked the question a while back. In another thread.


What if the delivery is not the pressure but the lines ability to supply an adequate amount of fuel quickly enough.


For an example GM built cars with 6 cylinders and small and big block 8's.


Each specific application required a fuel line according to the amount of fuel required for that engine.


My SS-396 Chevelle had the L78/375HP motor........that fuel line was larger than the 396/325&amp;350 HP cars got and a heck of allot bigger that the small blocks and 6 bangers got.


JUST A THOUGHT...................


Thttp://www.dieselplace.com/forum/smileys/Confused.gifNY

Ynot





Thru the ECM with a Tech II or equivalent ...


Mac

I also feel at this time time that the fluctuating rail pressures engineered into our system for optimum fuel delivery for varying conditions is well above the turn down rates of the INJECTOR itself anyway. I would be all out surprised if maintaining peak pressure would equate to more HP. It can however slightly increase the duration at which the HP pump and injectors see higher pressures when not needed and therefore result in a small increase in NEEDLESS wear.





So if this were true why does the stock fuel system in stock form maintain the proper fuel pressure at all times? Why would GM tell you to test for the variations as a possible source for low power customer complaints?


The truth is we are only trying to supply low pressure to the low pressure section of the pump, if anything it will help, not hurt the life of the pump assemble by providing proper lubrication. Think about it, the low pressure section of the pump assemble supplies the high pressure area as well as provides the lubrication to the internal bearings, camshaft and pistons as well as cooling for the unit. When it starts falling lubrication is now being limited. Addition wear being caused by longer duration of high pressure is hog wash. Every power enhancer is asking the Hp pump to do more than it did stock. Adding a lift pump to maintain the pressure and proper lubrication will only help lengthen the life of the pump! We are not raising the Hp only trying to maintain it!


As far as providing increases in power I have several dyno pulls on different trucks on different dyno's that prove that it does help. Many others here have also tested and come up with power increases from adding a lift pump. So if it were only one truck I might agree but I personally have seen it on no less than a dozen trucks and have read about the same amount here on the board, so I guess were all just lier's.


Let's look at this a different way. If you have a fixed cylinder volume and a fixed orifice to fill the cylinder. Now we assume that we can fill the cylinder 100% at "x" pressure and "y" time. How would you fill that same cylinder if we reduced "y" by a factor of 4?

They made different lines to compinsate for the lack or "performance" diaphram fuel pumps. After '72 or '73 or so, they were all 3/8" with a 7psi diaphram pump (regular RPO). SPO's and customs ended up with the same line, but the rebuildable type Rochester canister diaphram... Pardon my ignorance, but the latest posts seem to indicate the T-pump is not part of the HP pump. If not, is it electric, and is it the usual Bosch "rattle pump" (Carter)? The problem on other builds was not the line ID, but the high mounted electric transfer pump that has no ability to vaccuum. A booster electric was more often than not frame mounted, sitting in a pool of gravity fed fuel. I don't know what the GPH requirement is, but the late model rice burners have 65-80psi pressure from the pump, with 5/16 line. BTW, thanks Mackin. Anyones' modules read (or gonna read) rail pressure? They all seem to be can-bus. Thanks...T

Ynot





The duramax has no lift pump from the factory. It uses the low pressure pump with in the Hp pump assemble to draw the fuel from the tank thru the filter(s) to the pump on the front of the engine.

I also feel at this time time that the fluctuating rail pressures engineered into our system for optimum fuel delivery for varying conditions is well above the turn down rates of the INJECTOR itself anyway. I would be all out surprised if maintaining peak pressure would equate to more HP. It can however slightly increase the duration at which the HP pump and injectors see higher pressures when not needed and therefore result in a small increase in NEEDLESS wear.





So if this were true why does the stock fuel system in stock form maintain the proper fuel pressure at all times? Why would GM tell you to test for the variations as a possible source for low power customer complaints?


The truth is we are only trying to supply low pressure to the low pressure section of the pump, if anything it will help, not hurt the life of the pump assemble by providing proper lubrication. Think about it, the low pressure section of the pump assemble supplies the high pressure area as well as provides the lubrication to the internal bearings, camshaft and pistons as well as cooling for the unit. When it starts falling lubrication is now being limited. Addition wear being caused by longer duration of high pressure is hog wash. Every power enhancer is asking the Hp pump to do more than it did stock. Adding a lift pump to maintain the pressure and proper lubrication will only help lengthen the life of the pump! We are not raising the Hp only trying to maintain it!


As far as providing increases in power I have several dyno pulls on different trucks on different dyno's that prove that it does help. Many others here have also tested and come up with power increases from adding a lift pump. So if it were only one truck I might agree but I personally have seen it on no less than a dozen trucks and have read about the same amount here on the board, so I guess were all just lier's.


Let's look at this a different way. If you have a fixed cylinder volume and a fixed orifice to fill the cylinder. Now we assume that we can fill the cylinder 100% at "x" pressure and "y" time. How would you fill that same cylinder if we reduced "y" by a factor of 4?





Evidently you did not read my post completely or you are somewhat tunnel visioned. I was reluctant to post in this thread anyway so I won't go further.


I would however like to see the static(Dino) and dynamic(Real World) results from the dozen trucks you speak of.


If you look closely in my sig you will see that I run a lift pump. So where's my extra ponies at. I have absolutely no difference in seat of the pants feel. What have you seen on your DMax?Edited by: a bear

OOOPS HBC snuck in GrassHopper ...





Whats That Suppose To Mean?????





That my post was to be right after yours ....


Gheeeeesh do people seem a little touchy or is it me ....





Mac http://www.dieselplace.com/forum/smileys/Ermm.gif





Mac


Remember people in glass houses, remember the pot calling the kettle black.http://www.dieselplace.com/forum/smileys/HiHi.gif Some people don't like it when it happens to them.http://www.dieselplace.com/forum/smileys/Approve.gif

If I still had my Dodge, I'd show one worth 20hp. Not only did it increase hp, as it did on my last three trucks, but it even changed the sound of the engine (bumping timing by loading the plunger faster and harder with fuel, unloading shorter in the stroke of the pump, I think. It showed .8 degrees fast on a line pulse timing meter). No one else I know has broken 450hp with any truck (Ford &amp; IH, Cummins, GM...)that didn't have a second feed in series. It really does work. There's anecdotal evidence all over the boards on this, from all the different makes. It does seem to be common practice to make a class action nightmare of it tho ;-) ...T

That video is what you get when you stack the new Quad 215 Version 1.20 with the HJAT 145 in level 5. That is a programming problem, not a fuel delivery burst per se. I think that is timing causing a problem more than anything.





Brandon, I respect your opinion and I don't mean to appear contradictory but....FYI, My truck with the same stack V1.20 and HJAT 145 does the exact same thing as the video. Unless of course my tank is more than 1/2 full, then she runs all the way through the 1/4. Programming or fuel delivery? I don't know. Just my observations. I just chose to chase fuel delivery, cuz I personally can do something about that in the privacy of my own garage. http://www.dieselplace.com/forum/smileys/Big Smile.gif Less than 1/2 full, I'm working under the "slosh hypothesis". Launch truck, fuel slosh uncovers pick up canister, truck hesitates fuel runs forward, pump takes drink, truck launches again, fuel runs to the back uncovers pick up canister, truck hesitates, repeat as needed until common sense takes over and you lift.





Guy,


It's hard to say. My truck with that combo and a full tank (I never run with less than at least 1/2 as it helps the 2WD situation) will do the exact same thing every time. It will burst like that even on a rolling start where there is no comparision to a fully hooked boosted launch.


Like I said, every truck seems to digest things differently. When I first started stacking with the HJAT on my truck I had some minor burst issues, but it usually took till about 80 mph on a run to get it to manifest. That I felt was a fuel issue and the addition of my fuel system mods seems to have taken care of that.


All I know is I will keep working at it..... http://www.dieselplace.com/forum/smileys/Approve.gif

If I still had my Dodge, I'd show one worth 20hp. Not only did it increase hp, as it did on my last three trucks, but it even changed the sound of the engine (bumping timing by loading the plunger faster and harder with fuel, unloading shorter in the stroke of the pump, I think. It showed .8 degrees fast on a line pulse timing meter). No one else I know has broken 450hp with any truck (Ford &amp; IH, Cummins, GM...)that didn't have a second feed in series. It really does work. There's anecdotal evidence all over the boards on this, from all the different makes. It does seem to be common practice to make a class action nightmare of it tho ;-) ...T





Tony,


We have walked all over 450 HP without a secondary pump with the Duramax. http://www.dieselplace.com/forum/smileys/Approve.gif

Of course my observations were with the FASS installed. Without it my truck might act just like yours. I mean the bursting. I'm still way off of your HP. http://www.dieselplace.com/forum/smileys/Big Smile.gif But I'll keep trying as well.

If I still had my Dodge, I'd show one worth 20hp. Not only did it increase hp, as it did on my last three trucks, but it even changed the sound of the engine (bumping timing by loading the plunger faster and harder with fuel, unloading shorter in the stroke of the pump, I think. It showed .8 degrees fast on a line pulse timing meter). No one else I know has broken 450hp with any truck (Ford &amp; IH, Cummins, GM...)that didn't have a second feed in series. It really does work. There's anecdotal evidence all over the boards on this, from all the different makes. It does seem to be common practice to make a class action nightmare of it tho ;-) ...T





I layed down back to back 450+HP this Saturday at the CT DYNO DAY.


Single module.......no lift pump.....pulling thru a CAT filter and the Factory one.


It can and has been done.........


Thttp://www.dieselplace.com/forum/smileys/Embarrased.gifNY

If I still had my Dodge, I'd show one worth 20hp. Not only did it increase hp, as it did on my last three trucks, but it even changed the sound of the engine (bumping timing by loading the plunger faster and harder with fuel, unloading shorter in the stroke of the pump, I think. It showed .8 degrees fast on a line pulse timing meter). No one else I know has broken 450hp with any truck (Ford &amp; IH, Cummins, GM...)that didn't have a second feed in series. It really does work. There's anecdotal evidence all over the boards on this, from all the different makes. It does seem to be common practice to make a class action nightmare of it tho ;-) ...T








20 HP is not hard to believe on the earlier model trucks. What I would really like to see is a 20 HP increase on a HPCR system with a stock LP gear &amp; injection pump with stock injectors. Drawing a good looking pressure chart does not necessarily equate to a measurable increase in RWHP. A very minute change in volume which is not enough to change performance can cause a noticable sweep in pressure when you are dealing with a liquid packed system of small volume. In other words an almost non measurable volume may raise the pressure considerably but once it injects into the cylinder the difference in HP is almost not measurable just like the fraction of volume increase through the pos disp pumps were in the first place. The pressures we run on the rails are for atomization/efficiency not volume. Solenoid controlled injection is a totally different ball game. Why increase the duration of pressure on the componets for a gain of hardly nothing. If this pressure was for more volume we would have to fuel up around every corner. LOL And if you think these are complicated you should see the new lean burn Cats we now run to further reduce emissions. They need to be perfectly tuned. A small drift in any of many variables and things can get ugly in a hurry. Once tuned they do run well though. Also I have seen no difference period in 0-60 or 1/4 mile times when I shut off my pump......The results are in black and white. Think I'll just sit back on the fence and see where Diesel Techs high volume lift pump idea goes beyond fuel pressure charts.http://www.dieselplace.com/forum/smileys/Ermm.gif My best guess is not far. Edited by: a bear

I agree with Tony, 450+hp dosen't require a lift pump.


Also I can go to the track turn up the programing (make way more SMOKE) and run slower with less MPH (no lift pump) so please explain how fuel delivery is the problem?

JRmac,


abear wrote: "The pressures we run on the rails are for atomization/efficiency not volume."


your question---&gt; "explain how fuel delivery is the problem?"


Without the proper ammount of PSI you will flood the system. The fuel needs O2 to burn and what burns is the vapor. When the fuel enters the cylinder it is "atomized" or pushed in at such a great pressure that it forms a cloud of diesel fuel. With this cloud of fuel you have ample surface area, the part that burns. Once the PSI drops.......... the power drops off and the cloud becomes more like small rain......reducing the surface area. It will appear that more fuel is entering the chamber even though there is sligthy less fuel entering do to the PSI drop. It's sort'a like a fuel to air ratio.... more like a mass to volume issue.


I don't know if that made any sence to you or not? It's late...... I'll check back in after I pick up my flame suit. http://www.dieselplace.com/forum/smileys/Embarrased.gif





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif

JRmac,


abear wrote: "The pressures we run on the rails are for atomization/efficiency not volume."


your question---&gt; "explain how fuel delivery is the problem?"


Without the proper ammount of PSI you will flood the system. The fuel needs O2 to burn and what burns is the vapor. When the fuel enters the cylinder it is "atomized" or pushed in at such a great pressure that it forms a cloud of diesel fuel. With this cloud of fuel you have ample surface area, the part that burns. Once the PSI drops.......... the power drops off and the cloud becomes more like small rain......reducing the surface area. It will appear that more fuel is entering the chamber even though there is sligthy less fuel entering do to the PSI drop. It's sort'a like a fuel to air ratio.... more like a mass to volume issue.


I don't know if that made any sence to you or not? It's late...... I'll check back in after I pick up my flame suit. http://www.dieselplace.com/forum/smileys/Embarrased.gif





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif





This is Priceless


You really think these systems are losing atomization?http://www.dieselplace.com/forum/smileys/Wacko.gif You are crazy.

JRmac,


abear wrote: "The pressures we run on the rails are for atomization/efficiency not volume."


your question---&gt; "explain how fuel delivery is the problem?"


Without the proper ammount of PSI you will flood the system. The fuel needs O2 to burn and what burns is the vapor. When the fuel enters the cylinder it is "atomized" or pushed in at such a great pressure that it forms a cloud of diesel fuel. With this cloud of fuel you have ample surface area, the part that burns. Once the PSI drops.......... the power drops off and the cloud becomes more like small rain......reducing the surface area. It will appear that more fuel is entering the chamber even though there is sligthy less fuel entering do to the PSI drop. It's sort'a like a fuel to air ratio.... more like a mass to volume issue.


I don't know if that made any sence to you or not? It's late...... I'll check back in after I pick up my flame suit. http://www.dieselplace.com/forum/smileys/Embarrased.gif





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif





Burner, Well said! http://www.corvetteforum.com/zeroimg/smilies/iagree.gif

JRmac,


abear wrote: "The pressures we run on the rails are for atomization/efficiency not volume."


your question---&gt; "explain how fuel delivery is the problem?"


Without the proper ammount of PSI you will flood the system. The fuel needs O2 to burn and what burns is the vapor. When the fuel enters the cylinder it is "atomized" or pushed in at such a great pressure that it forms a cloud of diesel fuel. With this cloud of fuel you have ample surface area, the part that burns. Once the PSI drops.......... the power drops off and the cloud becomes more like small rain......reducing the surface area. It will appear that more fuel is entering the chamber even though there is sligthy less fuel entering do to the PSI drop. It's sort'a like a fuel to air ratio.... more like a mass to volume issue.


I don't know if that made any sence to you or not? It's late...... I'll check back in after I pick up my flame suit. http://www.dieselplace.com/forum/smileys/Embarrased.gif





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif





Burner, Well said! http://www.corvetteforum.com/zeroimg/smilies/iagree.gif I guess this is why other diesel injection systems operate under 4000psi with bigger nozzel holes make more power and don't SMOKE.

JRmac,


abear wrote: "The pressures we run on the rails are for atomization/efficiency not volume."


your question---&gt; "explain how fuel delivery is the problem?"


Without the proper ammount of PSI you will flood the system. The fuel needs O2 to burn and what burns is the vapor. When the fuel enters the cylinder it is "atomized" or pushed in at such a great pressure that it forms a cloud of diesel fuel. With this cloud of fuel you have ample surface area, the part that burns. Once the PSI drops.......... the power drops off and the cloud becomes more like small rain......reducing the surface area. It will appear that more fuel is entering the chamber even though there is sligthy less fuel entering do to the PSI drop. It's sort'a like a fuel to air ratio.... more like a mass to volume issue.


I don't know if that made any sence to you or not? It's late...... I'll check back in after I pick up my flame suit. http://www.dieselplace.com/forum/smileys/Embarrased.gif





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif





Burner, Well said! http://www.corvetteforum.com/zeroimg/smilies/iagree.gif


I guess this is why other diesel injection systems operate under 4000psi with bigger nozzel holes make more power and don't SMOKE.


More power with the same cubic inch and the same amount of air/boost? Please sight your examples.

It's not worth my time to debate this.


A lift pump is a fine thing,(and yes I do have one) fuel supply is not the problem to the 500 hp range. Nor is atomizationhttp://www.dieselplace.com/forum/smileys/Wacko.gif!!!


600hp or cure Bursting with a magic lift pump/line/sump setup forget-about-it.


Edited by: JRmac

It's not worth my time to debate this.


A lift pump is a fine thing,(and yes I do have one) fuel supply is not the problem to the 500 hp range. Nor is atomizationhttp://www.dieselplace.com/forum/smileys/Wacko.gif!!!


600hp or cure Bursting with a magic lift pump/line/sump setup forget-about-it.





Frankly its not worth my time to debate you either but I'm interested in learning about these engines. But your response is interesting. If I get the drift of your post, you know the answers we are seeking but are unwilling to discuss them. If you are unwilling to discuss them, what is the point of your participation in this thread? Except to make derogatory remarks to other members? I find your "I know something you don't know, attitude offensive". I'll make you the same deal I made CPMAC...if your selling something....I'm buying.....I've been buying....what's it gonna take? A bigger turbo, bigger nozzles, a camshaft replacement, head porting etc. All of those are pretty much no brainer, very obvious ways to increase power. Perhaps you would like us to take a step back in time....lets lower our fuel rail pressure to 4,000 psi and dump in a ton of fuel in really huge droplets that are hard to burn. Lets make it the really inefficient dirty sooty diesel engine of the past. The rest of the world continues to explore ways to increase and control higher rail pressures in both gas and diesel engines. Why do you think that is? Could it be atomization? Could a homogenous finely misted mixture actually burn quicker and make more power? You claim to know the secrets. I guess we here are just not worth your time or worthy of your brilliance. http://www.dieselplace.com/forum/smileys/Throw Up.gif

I meant that I was not going to debate about imagenary atomization problems!http://www.dieselplace.com/forum/smileys/Wacko.gif


I'm not trying to hender, I'm trying to help by getting your mind to thinking and maybe save you some wasted money.http://www.dieselplace.com/forum/smileys/Embarrased.gif


As for derogatory remark's? Didn't know that I did.http://www.dieselplace.com/forum/smileys/Shocked.gif

Trippin wrote:


Frankly its not worth my time to debate you either but I'm interested in learning about these engines. But your response is interesting. If I get the drift of your post, you know the answers we are seeking but are unwilling to discuss them. If you are unwilling to discuss them, what is the point of your participation in this thread? Except to make derogatory remarks to other members? I find your "I know something you don't know, attitude offensive". I'll make you the same deal I made CPMAC...if your selling something....I'm buying.....I've been buying....what's it gonna take? A bigger turbo, bigger nozzles, a camshaft replacement, head porting etc. All of those are pretty much no brainer, very obvious ways to increase power. Perhaps you would like us to take a step back in time....lets lower our fuel rail pressure to 4,000 psi and dump in a ton of fuel in really huge droplets that are hard to burn. Lets make it the really inefficient dirty sooty diesel engine of the past. The rest of the world continues to explore ways to increase and control higher rail pressures in both gas and diesel engines. Why do you think that is? Could it be atomization? Could a homogenous finely misted mixture actually burn quicker and make more power? You claim to know the secrets. I guess we here are just not worth your time or worthy of your brilliance. http://www.dieselplace.com/forum/smileys/Throw Up.gif








See you had the awnsers all along.http://www.dieselplace.com/forum/smileys/Clap.gif


Later I'm done here


JRmac http://www.dieselplace.com/forum/smileys/Cool.gifEdited by: JRmac

Ok....thinking out loud here.


You cant really compress a fluid. So the only way to get more fluid past the LP pump is to "sneak" it by the gaps in the pump gears/case right by increasing the pressure enough to cram it past the spaces? This is as long as the gears are getting filled with fluid to begin with. But if its not getting filled with fluid it would be cavitating like a MF.


Nothing wrong IMO with thinking outloud and bouncing ideas off each other. Yes lots of us will be wrong but so what? We keep throwing out wrong ideas they are bound to come up with a right idea in there. And even if we come up with what we think is right if we keep dumping out info and ideas and keeping an open mind and still searching even though we have already found something that makes perfect sense we may just come up with somehing better as apposed to sticking with something that would have worked fine. I like the dump as much ideas and info out there and explore those and do the sifting and save the "right or wrong" judgement for later. http://www.dieselplace.com/forum/smileys/Geek.gif


I have found this very interesting and ejoy the sharing of thoughts. Thanks for all the info and remaining pretty civilhttp://www.dieselplace.com/forum/smileys/Approve.gifEdited by: ratlover

BTW......if we take the low side of 10k PSI(thats about the lowest I have heard) and cram that through the orfice size of the injecters we have, do we think atomization is really a problem? JMO but I think even 10k psi is pretty freaking high but I really dont know.http://www.dieselplace.com/forum/smileys/Confused.gif

So, someone (I belive it was McRat) had a suggestion I believe made somewhat tongue in cheek that made sense. He mentioned running an "I-V" type fuel system.


So why not run a large 120v pump from a remote fuel cell for use on a dyno test?





Nick,


If you read this, I'm also curious as to where your regulator is located and where you are measuring psi? This is assuming that yours is the truck that does not show difference in psi drop from dyno to street.

has anyone gotten commanded and actual fuel rail pressure to stay the same in a full throttle 40-100 mph run in 4th & 5th gear or is a 3000 psi drop the best the HP pump can do?Edited by: mtomac

has anyone gotten commanded and actual fuel rail pressure to stay the same in a full throttle 40-100 mph run in 4th &amp; 5th gear or is a 3000 psi drop the best the HP pump can do?





No but the actual and command with an external lift pump has closed the gap considerably ....


Yes a 3000 PSI at min has been documented by way of freeze frames and the Tech II ...


I have to say that I also will countinue to run a extrnal lift pump as I believe it's benificial and has it's place ...


I just don't believe,YET, that it is the cure to get past the 500 ish threshold we're at ...


It is very possible that at the exsisting levels of power some of us are at that by not running a External Lift pump maybe harmfull in the long term to our fuel system componets ...


Having the system go to negative Vacuum can't be good ...


Will it allow our trucks to make more power ?? I doubt it from what I'm seeing as of late ... &lt;shrugging shoulders&gt;





Mac





Edited by: Mackin

The bottom line is not making more power it's about trying to solve problems. Different trucks run different with the same programming added, ever wondered why? When we know things that are fixed we begin to look at the differences. A common thread has been found to low HP and low fuel pressure, so lets start by fixing that! Will it be the end all be all fix..............NO. What it will do is eliminate the problem. The Hp pump is next as we are flowing very close to it limits with the torque and Hp we are making. I'm sure once we fix that, it will be something else. So why do it.................... because at the end of the road we will be making more power and have a better running vehicle.


For those of you that are happy at stock power levels leave your fuel system alone, stay away from modifications that cause air to appear into a fuel system that works perfectly fine as supplied by GM. If your modification needs another modification to solve a problem it has caused then your first modification is no good and get rid of it!


Why some of you try so hard to say it will not do any good instead of trying to help solve the problem is beyond me. When progress is made then you same people come back and say it can not be true. When questions are asked of you, you run away and hide.

Nick,


If you read this, I'm also curious as to where your regulator is located and where you are measuring psi? This is assuming that yours is the truck that does not show difference in psi drop from dyno to street.





My regulator is located in the back of the truck (not optimal) with the pump. i orignally had my autometer gauge hooked to the schrader port. i have since moved it to the bleed port on my OEM filter head:


http://dieselplace.com/forum/forum_posts.asp?TID=10123&amp;PN=1


My truck does show an equal PSI drop when run on the street as well as the dyno. i've run it on a dynojet as well as a 30 second 30-85MPH sweep on a mustang.. i've been able to pull it down to 2.5psi (worst case) on either dyno. it doesn't always drop to 2.5. sometimes it will only drop to 3 or 3.5.. basically its 6 psi crusing. once i whack the throttle it will drop immediately, come up about .5 -1 PSI and stay down until i get out of it..

I have to say that I also will countinue to run a extrnal lift pump as I believe it's benificial and has it's place ...



I just don't believe,YET, that it is the cure to get past the 500 ish threshold we're at ...


I think too much fuel and not enough air is why we are stuck at just over 500 rwhp on #2. The stock turbo can only move so much air before it's out of its efficiency range.

A lift pump did close the gap in actual vs. commanded fuel rail pressure by about 1500-2000 psi on my truck but it didn't make a difference on the track. But if a truck has a weak HP fuel pump, plugged fuel filter or something else that is causing rail pressure to drop 10000 psi I can see where power would be effected.

I just want to know if making fuel system modifications will keep the fuel rail pressure at 23055? I don't have a problem with modifying the stock fuel system if it is needed and I appreciate the work and testing that is being done here. If I didn't have full weekends or drag racing and truck pulling from the beginning of June to the end of September and I would try some things and do some testing myself. Edited by: mtomac

As Steve said, all trucks are not created equal.. mine is evidence of that, at least for me. i've never been able to put down the great #'s that others have, even with the same programming. i only picked up a handful of HP with the fuel pump, but my torque has gone up over 100 ft. lbs...





my actual vs. desired rail pressure used to drop over 10k PSI before the pump.. now that i have it it only drops about 3-4k in the beginning, and then it stays pretty close to good. if you see the post below:


http://dieselplace.com/forum/forum_posts.asp?TID=3079&amp;KW=diesel+power


you will see how poor it used to be prior to the pump.. bursting occured much earlier before the pump as well.Edited by: Diesel Power

Optimum would be to stick your bypass reg as close to the factory pump as possible but as long as you have the end PSI that you want(you need to measure close to the factory pump) then is it a big deal? Yes you will have quite a bit more pressure fluctuation I bet but I guess that is something we are still trying to decide if it is bad or not. I'm still curious if it matters if we are running .5 psi to the inlet of the pump or 20 what the difference is?


If you put a reg right before the EDU and ran fairly high pressure before the reg I bet you wouldnt have much fluctuation/drop up to the inlet of the pump anywho. And if you cut it down before the EDU you wouldnt have anything to worry about in the way of overpressurization short of making the fuel lines leak right? anyone have a setup like this? Or is everyones regs close to the lift pump?Edited by: ratlover

Optimum would be to stick your bypass reg as close to the factory pump as possible but as long as you have the end PSI that you want(you need to measure close to the factory pump) then is it a big deal? Yes you will have quite a bit more pressure fluctuation I bet but I guess that is something we are still trying to decide if it is bad or not. I'm still curious if it matters if we are running .5 psi to the inlet of the pump or 20 what the difference is?


If you put a reg right before the EDU and ran fairly high pressure before the reg I bet you wouldnt have much fluctuation/drop up to the inlet of the pump anywho. And if you cut it down before the EDU you wouldnt have anything to worry about in the way of overpressurization short of making the fuel lines leak right? anyone have a setup like this? Or is everyones regs close to the lift pump?





Ummm... there is pretty good chance that has already been done. http://dieselplace.com/forum/smileys/Wink.gif

I figured someone had done it.......


So how does that persons fule pressure look I wonder? http://www.dieselplace.com/forum/smileys/Wink.gif

Let me reiterate. This is my first Duramax. I haven't even changed oil on one yet. All of my light duty has been on my own stuff. I do custom freebie work on some pickups for buddies or at diesel site functions, but not as part of Welch Diesel or the LLC subsidiary. The other makes all run secondary transfer pumps on the big dogs. All of them. It was a PM thing (preventive maintenance), not an HP thing. I never said it couldn't be done, and didn't imply that. I just said I knew no one... Now I do. Cool. When pressures drop to 1psi and below, things start to blow apart, as they are all lubed by non-cavitated or aerated fuel. Some saw an increase in HP with a booster pump, others didn't. No equations or formulas to explain why. Just the way it is. I'll run a secondary even if I lose power. Again back to the PM thing. It's a proven fact that more pressure will increase the life of a starved component, not vice-versa.


Most motors will make more power with lower pressures (to a degree) to the injector. A decrease in atomization causes a slight decrease in timing, but the duration of the combustion process is greatly increased, driving the piston down longer. You blow more smoke, but have higher readable torque as a result. Extrude hone injectors make more power than stock holes multiplied (i.e. 5 holes at .009" will make more power than 9 holes at .005" [example- not actual numbers]) for that reason. The same thing happens with decreasing compression. More smoke, longer burn, less efficiency, more power. Basic stoiciometric efficiency principals. Not really rocket science.


Going outside the map range of a turbo is not a bad thing short term. It takes a lot longer than you think to heat soke an aftercooler, and cures itself pretty quick when boost levels drop. I've run 15 to 20psi above the map range of many turbo's from all the big boys (Switzer, Holset, Garrett, customs...), even on over-the-road trucks with 40+ minute hard pulls, and it's all power. Never had a heat prob on anything yet, and the turbo's life isn't hindered at all, thus far. The day is yet young tho http://www.dieselplace.com/forum/smileys/Big Smile.gif


I'm takin Friday and the weekend off and tearin into this thing. Can't take it much more. I'll have some pressure numbers and a good build with a secondary filter and pump by Monday. No way to check rail pressure yet, but I don't have any HP mods to compensate for yet either (and not really wantin to wait 'til Fall for production stuff on the LLY either, but oh well) Have fun guys...T

You can also read rail pressure with an OTC Genesis. I think that not being able to maintain rail pressure is a problem. But, I dont think we are going to gain much power with keeping rail pressure up with our stock turbos. Now, with a BIGGER turbo, I think we could benefit a lot from maintaing our rail pressure. I just dont think we are going to see big gains yet with fixing our fuel system. I think we need to figure this out though and fix our fuel system to get the power out of them in the long run and to maintain longevity of the hp pump.

I haven't officially tested it, BUT my Superflow is now set up and configured to read the analog voltage output of the OE rail sensor and record in real time...





Should be interesting. You can bet your life on one thing though. If it DOES make a difference I'll be the first to admit it. Wouldn't be the first "I stand corrected" post I made...

Not that I feel it will change any of the nay sayer minds but here is some real proof of the gains on a 2003 hot juice level 5 test. One run is with the stock fuel system and the other is the same truck on the same dyno after installation of a FASS lift pump. As you can see the two runs pretty much over lay each other up to 2800 RPM but above that look out! A gain of 16 Hp @2980 rpm and more above that. http://www.dieselplace.com/forum/smileys/Big Smile.gif


http://www.dieselplace.com/forum/uploads/pump_Vs_no_pump.jpg

WD, correct me if I'm wrong, but I thought I read this turbo is only pumping 35psi as of now. That's actually only about 55,000 rpm. I'm not all that sure about the controllabilty of the variable venturi thing (which should yeald rediculous gains, as people have been working on that design for 25 years or so [Cummins tried a couple Holset designs twice, and they were too sticky, but had devistating boost] with no success), but that turbo will spin 75,000rpm easy, landing it around 46psi+. That's plenty for well above 600hp below 3,700 rpm. Controlling the VVR should get it above 50psi. It'll split the compressor wheel around 54psi, and that'd be stupidly expensive.


Kennedy and DT, good posts, for sure. This is how this stuff gets fingered out http://www.dieselplace.com/forum/smileys/Approve.gif ...T

I'd be curious to see the lower side of that chart that shows the RPM range most of us run at cruising and towing 1750 to 2400 Rpm. I rarely see anything above 3000 unless I am passing a vehicle or drag racing the competition.

a bear


So far you have claimed to be the expert and offered no help in solving the problems. Every question you've been asked in the area of your expertize you refuse to answer. You ask for proof, you got it. There is an old saying my father taught me many years ago.................


If your not part of the solution your part of the problem.

has anyone gotten commanded and actual fuel rail pressure to stay the same in a full throttle 40-100 mph run in 4th &amp; 5th gear or is a 3000 psi drop the best the HP pump can do?


I can,


50mph to 120mph 5th gear.


FASS+TTS Extreme

has anyone gotten commanded and actual fuel rail pressure to stay the same in a full throttle 40-100 mph run in 4th &amp; 5th gear or is a 3000 psi drop the best the HP pump can do?


I can,


50mph to 120mph 5th gear.


FASS+TTS Extreme





How bout a wot run???? And does it seem to matter how much fuel is in the tank????Edited by: heartbeatcanada

a bear


So far you have claimed to be the expert and offered no help in solving the problems. Every question you've been asked in the area of your expertize you refuse to answer. You ask for proof, you got it. There is an old saying my father taught me many years ago.................


If your not part of the solution your part of the problem.





I ask a simple question and you become like a fly on a toilet seat.


If you think I'm not part of any solutions where the hell your head's been shoved. I think most here will testify I was the first to use the lift pump on the DMax many thousand miles ago. Or possibly the second and near 50K miles ago. I had to defend my theorys back then and every thing I done was posted and well documented well before you even thought about visiting these forums. I've probably been fooling w/ diesel engines since you were $hitting yellow and have probably forgotten more than you will ever know about any tropic you care to discuss. To the best of my knowledge I know of no question you asked nor have I avoided any question asked by any member that I knew the answer to so shoot one out and I will do my best to answer it of attempt to find an answer. I am human and I don't have all the answers or claim to have. People who are know it alls like yourself usually don't ask many because their pride keeps them in the dark. I don't have to come out and say where your knowledge base resides because it is apparent in your daily posts for all to see. You are in left field. If you can convince enough folks here that they need a min. 150 GPH lift pump for upwards of 600.00 that still will not provide consistant pressure and only to make minimal gains after 3000 RPM I will gladly eat crow. If I've told you once I've told you 1000 times there is not a pump made that will prevent inertia fluctuations......Untill then STFU.http://www.dieselplace.com/forum/smileys/Angry.gif


On Edit: If you claim that if I'm not part of the solution I must be part of the problem then what exactly is the problem you speak of. Fuel starvation ?????? I am still curious. Do you own one of these trucks and are you truely a Diesel Tech.Edited by: a bear

has anyone gotten commanded and actual fuel rail pressure to stay the same in a full throttle 40-100 mph run in 4th &amp; 5th gear or is a 3000 psi drop the best the HP pump can do?


I can,


50mph to 120mph 5th gear.


FASS+TTS Extreme





How bout a wot run???? And does it seem to matter how much fuel is in the tank????





I'm not sure what you mean by WOT run. This was a wide open throttle run actually on the way home tonight, I was on the freeway coming home tonight and was thinking about the discussion here from last night and thought that I should see if I was holding pressure. Tech 2 was handy so I slowed her down to 50 and let her fly, stayed in it until I ran up on some traffic at 120. Reviewed the snapshot and much to my surprise she held rail pressure. I thought...wow pretty cool. Then I got home and read Mtomac's post.


I must be spending way to much time on this board, if you guys can post a message and I recieve it telepathically on my drive home! http://www.dieselplace.com/forum/smileys/HiHi.gif


The tank was at 5/8 to 3/4. Hope this helps!

The term critical flow often used in my line of work simply means that once you reach the flow capacity of a given orifice you simply will not move more through it by increasing or maintaining pressures above the threshold of that given orifice design. You have simply reached the max thruput built into this orifice design (size).



Exactly! Pressure vs orifice! Now lets assume .312 ID line...I'm guessing here, but assuming somewhere in our fuel system we are moving through a .312 or maybe even smaller orifice. What is the positive pressure that causes critical flow to occur, (assuming a straight line .312 orifice system) and what is the flow in GPH based on a specific gravity of.......oh I don't know, lets just say .86








I also feel at this time time that the fluctuating rail pressures engineered into our system for optimum fuel delivery for varying conditions is well above the turn down rates of the INJECTOR itself anyway. I would be all out surprised if maintaining peak pressure would equate to more HP. It can however slightly increase the duration at which the HP pump and injectors see higher pressures when not needed and therefore result in a small increase in NEEDLESS wear.





So if this were true why does the stock fuel system in stock form maintain the proper fuel pressure at all times? Why would GM tell you to test for the variations as a possible source for low power customer complaints?


The truth is we are only trying to supply low pressure to the low pressure section of the pump, if anything it will help, not hurt the life of the pump assemble by providing proper lubrication. Think about it, the low pressure section of the pump assemble supplies the high pressure area as well as provides the lubrication to the internal bearings, camshaft and pistons as well as cooling for the unit. When it starts falling lubrication is now being limited. Addition wear being caused by longer duration of high pressure is hog wash. Every power enhancer is asking the Hp pump to do more than it did stock. Adding a lift pump to maintain the pressure and proper lubrication will only help lengthen the life of the pump! We are not raising the Hp only trying to maintain it!


As far as providing increases in power I have several dyno pulls on different trucks on different dyno's that prove that it does help. Many others here have also tested and come up with power increases from adding a lift pump. So if it were only one truck I might agree but I personally have seen it on no less than a dozen trucks and have read about the same amount here on the board, so I guess were all just lier's.


Let's look at this a different way. If you have a fixed cylinder volume and a fixed orifice to fill the cylinder. Now we assume that we can fill the cylinder 100% at "x" pressure and "y" time. How would you fill that same cylinder if we reduced "y" by a factor of 4?





Evidently you did not read my post completely or you are somewhat tunnel visioned. I was reluctant to post in this thread anyway so I won't go further.


I would however like to see the static(Dino) and dynamic(Real World) results from the dozen trucks you speak of.


If you look closely in my sig you will see that I run a lift pump. So where's my extra ponies at. I have absolutely no difference in seat of the pants feel. What have you seen on your DMax?








Let's see here are two from this very post you have ignored, let's see your answers! Yes, I own a Duramax and you must have your tunnel vision on if you cannot figure out who I am and what I do for a living, if you bothered to read this forum at all you would know. I also happen to own two chassis dyno's and one engine dyno with test cell. We

Ditto...


I'd be curious to see the lower side of that chart that shows the RPM range most of us run at cruising and towing 1750 to 2400 Rpm. I rarely see anything above 3000 unless I am passing a vehicle or drag racing the competition.


Show me the graph. What happens below 1800rpm?

Ditto...


I'd be curious to see the lower side of that chart that shows the RPM range most of us run at cruising and towing 1750 to 2400 Rpm. I rarely see anything above 3000 unless I am passing a vehicle or drag racing the competition.


Show me the graph. What happens below 1800rpm?





I wouldn't think it would make a difference at lower RPMs or at cruise (not WOT) as the engine has not taxed the stock fuel system's capacity to deliver fuel.

Yeah, perhaps it won't.


I wouldn't think it would make a difference at lower RPMs or at cruise (not WOT) as the engine has not taxed the stock fuel system's capacity to deliver fuel.


I could infer from that remark that the $600 F.A.S.S. is not necessary most of the time for most of Duramax's....unless of course there is something more magical about the F.A.S.S. lift pump as compared to any other device that provides enough positive fuel pressure to eliminate bubbles. Personally, it's an attractive somewhat compact package with a little extra capacity to sustain higher horsepower and I will grant you that if anything is removing bubbles from the fuel it will probably only help as far as longevity is concerned providing that the pressure at which the F.A.S.S. for instance operates at is not too high. The ideal set up to me is a pre-lift-pump filter; then lift-pump; then pre-OEM filter and I pretty much count the OEM as inadequate or null. Hmmm…. The overall cost of the alternative isn’t cheap either.


In the case of the F.A.S.S. being it is a higher flow pump, I wonder how high the bypass flow back to the tank is and how that would impact the tank temperature.


Humor me. I want to see the rest of the story.http://www.dieselplace.com/forum/smileys/Geek.gif

ynot, you may be talking the LLY turbo, I am talking about the LB7's turbo, I have seen over 30psi with the wastegate blocked, I also lost that turbo doing that. Now with the wastegate functioning I see a max of about 30psi or so. My truck still smokes a solid stream of smoke at wot with full boost.

WD, do you know the actual turbo number, or the wheel or housing size, and does it have a compressor bleed? I've never seen a turbo split that low, unless it's like the old 6.5 pre-cup turbo that had very over-exagerated turbine clearance so they would only pull 10-12psi (they knocked the bottom end out with over 14psi, unless it was built for that with splayed mains, etc). Sorry for the confusion. I'll add LLY to my sig. Have a good day...T

There a compressor map out there somewhere, not sure if that will tell you anything though....

I read that map and thought that it implied 36psi (to 38psi) was the most efficient pressure. I asked what others thought from the map and got no reply. Since then I have played it safe at 32psi.

WD, you lose if from over boosting it or barking it? was it catostrofic or what? What did you run it to before that?

mine maintains fuel rail pressure with the fass but would not with the fm 100........to each their oown guys if you dont think you need it then so be it......Some here know the benefits.........WTF

I dont think any one here has said that its not a good idea. Some have doubted weather it will improve HP but I dont think anyone is questioning its usefullness.


So what happens to the pressure to the inlet with a reg close to the EDU? What kind PSI is running to the reg? What kinda reg?


You cant really compress a fluid. So the only way to get more fluid past the LP pump is to "sneak" it by the gaps in the pump gears/case right by increasing the pressure enough to cram it past the spaces? This is as long as the gears are getting filled with fluid to begin with. But if its not getting filled with fluid it would be cavitating like a MF.


Any thoughts on this Diesel Tech? or others? Am I correct in thinking this way???http://www.dieselplace.com/forum/smileys/Confused.gif

mine maintains fuel rail pressure with the fass but would not with the fm 100........to each their oown guys if you dont think you need it then so be it......Some here know the benefits.........WTF





So Dave what





Ah never mind ....





Mac http://www.dieselplace.com/forum/smileys/HiHi.gif

You cant really compress a fluid. So the only way to get more fluid past the LP pump is to "sneak" it by the gaps in the pump gears/case right by increasing the pressure enough to cram it past the spaces? This is as long as the gears are getting filled with fluid to begin with. But if its not getting filled with fluid it would be cavitating like a MF.


Any thoughts on this Diesel Tech? or others? Am I correct in thinking this way???http://www.dieselplace.com/forum/smileys/Confused.gif





What is being missed here is that there is a cavity to fill in the low pressure pump. This cavity must be filled over and over again as the pump rotates. What if this cavity is only being filled 50% in stock form? If that produces enough volume for the high pressure section, the internal lubrication of the pump and cooling it is perfectly fine! Now let's increase the demand by adding more Hp as we all are talking about in this discussion. Is 50% fill adequate any longer? The easiest way to check is look at the pressure output of the High pressure pump. In stock form the output follows what is being commanded by the ECM just fine, but add a high Hp program and it will no longer follow. Now remember that as engine speed increases we have less and less time to get the job done. What has happen...................... we exceeded the capacity of the high pressure system to keep up. So we start looking into why and find the low pressure side has also dropped. The easiest solution is to get the low pressure problem solved then look at the high pressure again. Testing has shown that if you get the low pressure back in line the high pressure comes back in line. So the question becomes how much is needed to fix the low pressure problem. Well that all depends on how much Hp your trying to add. So for those with small power adders not much if any is needed, but go to high Hp of let's say a Edge HJ with attitude on level 5 and you can see the results posted above. The higher the HP required the larger the lift pump needed. Now all engines are not the same. Our testing has shown that. Look at Diesel Power's truck he picked up 100 ft/lbs of torque, look at the truck I posted the results for, it picked up 20 Hp. These are very solid gains.


A lift pump only needs to be large enough to solve the problem any extra is just that extra. The pump assemble that we are currently working on is an on demand system. What this means is it will only supply what is needed when it's needed. http://www.dieselplace.com/forum/smileys/Thumbs Up.gif

I understand were you are coming from on all the above but am still a bit fuzzy on a few things…..


Say the cavity is being only .5 way filled then what is filling the rest of the cavity? It must be a gas right? You cant compress diesel and you allso cant "strech" it right?


I’m also not questioning if something works or not…..I could care less right now, I’m just wondering why. I’m saving putting stuff into the “right and wrong” boxes latter, I’m just out collecting info now.


Interesting stuffhttp://www.dieselplace.com/forum/smileys/Thumbs Up.gif

edit......if it all boils down to a "we dont know why the hell it works other than it does" I dont mind that either.....Like I said my truck will be getting a lift pump. There are just a few questions I have though....

And also how will your pump know how much is just right? ? The only way to change the output of a pump is by spinning it at a different rate right? So you are either changing the voltage going into it or you need to control it with a reg that either bypasses the unused fuel back or it wont let more than a certian PSI build up on the other side. Right? A pump running at full output with a bypass reg downstream would be a "demand" type system, but without some funky electronics I dont see it being vary easy to have a truely demand type pump. Sorry, I'm trying to pry out details before you guys even release it for testinghttp://www.dieselplace.com/forum/smileys/Embarrased.gif Witch I may be interested in doinghttp://www.dieselplace.com/forum/smileys/Wink.gif

I understand were you are coming from on all the above but am still a bit fuzzy on a few things…..


Say the cavity is being only .5 way filled then what is filling the rest of the cavity? It must be a gas right? You cant compress diesel and you allso cant "strech" it right?


I’m also not questioning if something works or not…..I could care less right now, I’m just wondering why. I’m saving putting stuff into the “right and wrong” boxes latter, I’m just out collecting info now.


Interesting stuffhttp://www.dieselplace.com/forum/smileys/Thumbs Up.gif








If you filled a cylinder with liquid and no air, and expanded the cylinder (pull out on the piston), the piston will rise. What is in the "gap"? Low pressure vapor that has out-gassed from the liquid. It is not air, nor is it a vacuum. Fuel will out-gas in a vacuum.


So at least in theory, you could have a gerotor pump only pushing 50% volume due to out-gasing at low pressure. Does it happen? Hell if I know, but this is an interesting thread, even if you don't want 600hp.

So, someone (I belive it was McRat) had a suggestion I believe made somewhat tongue in cheek that made sense. He mentioned running an "I-V" type fuel system.


So why not run a large 120v pump from a remote fuel cell for use on a dyno test?


Nick,


If you read this, I'm also curious as to where your regulator is located and where you are measuring psi? This is assuming that yours is the truck that does not show difference in psi drop from dyno to street.





It wasn't really "tongue-in-cheek", just not practical for more than 5 PSI. It would supply 5 psi at very large flow rates if you used a garden hose sized tube. It would eliminate any issue with fuel heating, pump volume, filter restriction, fuel pickup issues, G-force, etc. You would want to start with filtered fuel, and do it on a dyno.


But all it would do is isolate conditions. It would not supply an answer.

And also how will your pump know how much is just right? ? The only way to change the output of a pump is by spinning it at a different rate right? So you are either changing the voltage going into it or you need to control it with a reg that either bypasses the unused fuel back or it wont let more than a certian PSI build up on the other side. Right? A pump running at full output with a bypass reg downstream would be a "demand" type system, but without some funky electronics I dont see it being vary easy to have a truely demand type pump. Sorry, I'm trying to pry out details before you guys even release it for testinghttp://www.dieselplace.com/forum/smileys/Embarrased.gif Witch I may be interested in doinghttp://www.dieselplace.com/forum/smileys/Wink.gif


I like keeping is simple too. Here are a few things to keep in mind.
One of the biggest restrictions in most fuel systems is the "dead-head' regulator. Dead-head regulators are popular because you do not need to install a return line. However, they are not only more restrictive but also create several other problems that can be eliminated with a return-style regulator. Dead-head regulators also have a higher failure rate than return-style regulators.

Dead-head regulators regulate pressure by starting and stopping flow. Return regulators regulate pressure by sending excess fuel back to the tank in a continuous cycle.

Because a dead-head regulator starts and stops flow, fuel pressure between the pump at regulator is higher than the pressure between the regulator and the carb (or injectors). However, if the pressure gets too high, it can and will damage the fuel pump. Therefore, the pressure coming out of the pump is limited by a device built into the pump called a bypass. Low pressure pumps are limited to less than 9PSI and should not be used with dead-head regulators. High pressure pumps are limited to a pressure of between 10 and 25PSI.

Not only can the fuel pumps being used with dead head regulators fail because of pressure issues, but pumps with dead head regulators also run hotter do not last as long as when connected to to a return-style system because it is the fuel that cools the pump. Pounding the fuel because it can not move creates more heat.

The bypass in the pump can malfunction. This can cause the pressure to drop or increase so much that the pump motor fails. Even if the bypass in the pump is working correctly, it is still possible to have a pressure dr

What the ............





I got a headache





Mac http://www.dieselplace.com/forum/smileys/Sleepy.gif

Yeah, perhaps it won't.


I wouldn't think it would make a difference at lower RPMs or at cruise (not WOT) as the engine has not taxed the stock fuel system's capacity to deliver fuel.


I could infer from that remark that the $600 F.A.S.S. is not necessary most of the time for most of Duramax's....unless of course there is something more magical about the F.A.S.S. lift pump as compared to any other device that provides enough positive fuel pressure to eliminate bubbles. Personally, it's an attractive somewhat compact package with a little extra capacity to sustain higher horsepower and I will grant you that if anything is removing bubbles from the fuel it will probably only help as far as longevity is concerned providing that the pressure at which the F.A.S.S. for instance operates at is not too high. The ideal set up to me is a pre-lift-pump filter; then lift-pump; then pre-OEM filter and I pretty much count the OEM as inadequate or null. Hmmm…. The overall cost of the alternative isn’t cheap either.


In the case of the F.A.S.S. being it is a higher flow pump, I wonder how high the bypass flow back to the tank is and how that would impact the tank temperature.


Humor me. I want to see the rest of the story.http://www.dieselplace.com/forum/smileys/Geek.gif





TREX,


I personally don't think a $600.00 Fass is necessary for most Dmaxes. I'm a performance nut, I'm probably should be concerned about entrained air, but I'm not, so I haven't really concentrated any effort to discover whether or not that part of the FASS works or not. I wanted to do 2 things, add a lift pump strictly for Hot Rod stuff and add additional filtration. I haven't noticed a fuel temperature increase with the FASS using Tech 2 but I didn't really study it either. I just look at the temp occasionally because I'm curious. Of course every thing the FASS bypasses to the tank has been filtered and continues to get filtered every trip it makes through the pump assembly. Obviously adding additional filtration further restricts any fuel system from its stock configuration. So in my mind I needed a serious pump. The FASS prefilters fuel before it gets to its own pump, having two filters on the FASS allows you to prefilter and filter to basically anything you want, from 30 micron to 3 micron. The pressure is also adjustable. So, in my tiny little mind, I added up the cost of Aux. filtration + Aux. pump + mounting both in seperate locations and decided to go FASS. Hope this helps!

BMDMAX,


Pretty cool race car stuff under your hood there! http://www.dieselplace.com/forum/smileys/Cool.gif


Where is your regulator return plumbed to?


How much pressure are you running?


Thanks in advance!

BMDmax, I agree 100% with your thoughts of going with a return style reg. I actually plan on running one but plan to run it right after the factory fuel filter(I plan to run a pre CAT with a lift BTW at this satge of the game.) An excellent description though!http://www.dieselplace.com/forum/smileys/Clap.gif So does your fuel pressure on the outley to the reg stay pretty constant? Do you set your pressure at 8PSI? Edit:you need some purdy SS braided linehttp://www.dieselplace.com/forum/smileys/Tongue.gif


McRat....we are thinking 100% along the same lines.


Like I said....if its not filling the pump 100% its cavitating like a MF right guys?


Edit: trip I have thought of the FASS or perp set up just for your reasons....hard to complain about a kit form with all its ease....but then its not a return style set up unless you add a reg alsohttp://www.dieselplace.com/forum/smileys/Cry.gifEdited by: ratlover

BMDMAX,


Pretty cool race car stuff under your hood there! http://www.dieselplace.com/forum/smileys/Cool.gif


Where is your regulator return plumbed to?


How much pressure are you running?


Thanks in advance!








The return goes back to the tank. I run 12 PSI on my system.

on the low side of the reg?





On a side note according to the Holley and the Mr. Gasket techs(mallaroy) they dont have any diesel compatible fuel pumps.http://www.dieselplace.com/forum/smileys/Confused.gif

on the low side of the reg?





On a side note according to the Holley and the Mr. Gasket techs(mallaroy) they dont have any diesel compatible fuel pumps.http://www.dieselplace.com/forum/smileys/Confused.gif





I am running 12 PSI on the outlet side of the regulator, set by measuring at the schrader test port.


I know they don't rate the pump for diesel, not even the marine version. That is why I have my connections setup to bypass the pump is just a matter of minutes if need be.


I don't know how long it will really last but time will tell. The main issue is accelerated brush wear on the pump. At least I can rebuild it easily.

thats what I figured.


One reason why any pump I buy must be either garanteed, rebuildable or cheap.


I thought brush wear had to do with added load on the motor generaly? If you work it they wont last as long....diesel cant be much harder to pump than gas? I just figured why some wernt rated for diesle is they werent tested for it and the manufacture didnt want to go on a limb or they knew it would eat/swell/otherwise piss off the seals/seats ect???

thats what I figured.


One reason why any pump I buy must be either garanteed, rebuildable or cheap.


I thought brush wear had to do with added load on the motor generaly? If you work it they wont last as long....diesel cant be much harder to pump than gas? I just figured why some wernt rated for diesle is they werent tested for it and the manufacture didnt want to go on a limb or they knew it would eat/swell/otherwise piss off the seals/seats ect???





Mallory claims the big problem is that it is harder to pump the diesel than the gas. I don't claim to know specific gravities or flow dynamics versus the two fuels but I guess I will see how long the brushes last.


Diesel will attack the seals differently but I think that risk is pretty low with this pump design since the shaft seal won't get hit with much fuel when mounted properly and there are no vanes or diaphrams to degrade.


The real problem is finding any decent pressure and high flow rate pumps from the racing world that can handle diesel.


I will just muddle along for now. http://www.dieselplace.com/forum/smileys/Wink.gif

Hoping to acquire a 5 gpm fuel turbine sometime in the near future. This will be quite useful in testing fuel flow. Also had a DANDY little display stand built for my fift pump. Even a lid for the fuel "pot" to keep it clean. If you ever doubt the need for a fuel cooler, just recirculate a gallon of fuel for a couple of hours.





Oh yeahm, we have Eric's bratwurst soaking in the diesel pot as we speak...

The real problem is finding any decent pressure and high flow rate pumps from the racing world that can handle diesel.


I will just muddle along for now. http://www.dieselplace.com/forum/smileys/Wink.gif





This is the exact same problem I have been talking about, something so simple I thought it would be no big deal, boy was I wrong. This has forced us to working on getting a pump built that would supply the necessary volume/ pressure and work with diesel fuel. We have placed a 3000 hour life span on the pump assemble to keep it durable. Things are in the works and we should know what the cost should be over the next month. We are looking at offering a pump only and a pump filter combination.

I also looked into one of the Mallory pumps months ago as I am a distributor for Mr. Gasket products. Price is right, flow is right, but after some lengthly discussions with tech suport, they said no go for diesel fuel. A one off pump for competition use only is not a problem. It is when you start putting them on trucks used on a daily basis it becomes more complicated. The avg person isnt going to want to plumb a $1500 fuel system in their diesel truck. If this wasnt the case, we could have solved this problem months ago.


We need something effective, simple, yet affordable. Something that will not overheat, not be suseptable to the elements, handle diesel fuel, will not leak, flow enough volume, be reasonably quiet, and affordable. Unfortunately when combining these things you run into a pump that doesnt exist. Luckily DieselTech has stepped up to the plate on our behalf. I just hope i can be patient enough, b/c without a lift pump on the extreme you will probably hit the low fuel cutout :-) Once you non lift pump believers put real programmers in your truck then introduce nitrous into the equation you will understand that the lift pump in itself will not make a drastic increase in hp, but it will open the door for more power to be made.

Once you non lift pump believers put real programmers in your truck then introduce nitrous into the equation you will understand that the lift pump in itself will not make a drastic increase in hp, but it will open the door for more power to be made.





Amen http://www.dieselplace.com/forum/smileys/Clap.gif

When, the turbo went, it didnt come part, I believe it just took out a bearing as it, started making a really low but loud whining sound when you started getting some rpm or boost. It did this at about 36-38psi. I had barked it before, but didnt at the time. I did a full throttle run from a stand still, noticed after I let off and got back on it. Oh, this was the first day I had a 200+ box!

The other issue (for some) is findingh one that doesn't sound like an old electric can opener...





I've got a Mallory 140 on my old mud truck that's been around for about 10 years. Still works well. The log on my Dominator leaks like a sieve though...

Boy this is fun. http://www.dieselplace.com/forum/smileys/Wink.gif Turbo efficiency map really doesn't mean squat. Just the number of psi that it's starts producing more heat than they think it should (usually 330*). Run em!!! The only real number we need is what boost (as in what turbine R's) the compressor wheel splits at. 35 is very low, tho I started collecting parts for this weekend, and the only gauge I could get to match the FP gauge is 35psi. I'll either peg it and kill it or call it good there. Not sure yet, as I have nothin else to bolt on this motor for power. Anybody care to relinquish their new Edge? Just kiddin guys. I will have the affore mentioned stuff installed by Sunday, with FP only reads, FP with booster pump reads, and FP thru secondary filter with booster pump. The primary filter head is after the OEM transfer pump, yes?? Thanks guys and ya'll behave!!! http://www.dieselplace.com/forum/smileys/Big Smile.gif ...T


My first edit. Cool... I just noticed how goofy this looks. The truck is three weeks old on Monday. Wonder why I'm divorced........... Edited by: ynot

ynot, Quad has a box out for the LLY. I know PPE also has a box built, dont know if they have released it yet, but they had it at Muncie.

My KD HJ 4.61 peaks at 25 psi.Has anyone compared the hp and torque figures at 25 psi vs the higher boost numbers?If so what are they?


Blake

First off a reasonable lift pump is a good idea for several reasons but not for more hp out of an otherwise stock fuel system. I have made more hp than most with a Duramax and did that in front of several at an event and not off in the corner of a shop by myself, I also made big hp without a lift pump. GM giving us a system that will make around 500 hp without any modification is great but at that level several thing if not the whole system are overworked. Trying to band aid the system with a lift pump that flows a ridiculous amount like 180 gph isn't going to help anything. You need to start with the biggest problem at this point which is the injectors. We are already stretching the injector pulse far enough to be injecting fuel at less than desirable times. We have already found that the Duramax with stock injectors and turbo will make just over 500 and no amount of fuel shoved to the to the stock system is going to make much improvement. You just can not pass any more fuel through the stock injector in a timely manner. Then when you do add injectors and allow the pump to get more fuel into the cylinder you are for the most part already out of air with the stock charger so you need to upgrade that also. When you do upgrade injectors and airflow then it is going to require different programming to make that equipment work efficiently. It is going to be expensive to get to the 600 hp range but a fuel pump big enough to supply a 1000hp gas engine will not help enough to be worth the cost before or after injector and turbo upgrades. You need to realize that the stock system moves less than 20gph and still will generate 500 rwhp ( it has been done by several people) so why on earth would you think you would need a pump over 50 or so gph to maintain 600 rwhp? The motor isn't going to use that much more fuel so if you can't maintain pressure then you must be returning way to much. Maybe you need to work on getting the fuel these reasonable size pumps generate to the right place instead of sending it back to the tank?


Basically if you need more power than you get from a good stack of programs then you are going to spend a lot of money to get to the next level. GM really made it easy and reasonably cheap to get up in the high 400 rwhp range compared to what was available in the past and other brands but to go to 600 rwhp is going to seperate the crowd. I'm sure there are some trucks out there that have issues of some sort that may show big hp improvements but it has to be a small percentage because I have dyno tested several trucks and haven't found one that made any extra hp with a lift pump and yes I have some big lift pumps.

Zoidbureg, I think these folks are try'n to get to 600HP without injectors...... I think.


However, It would be nice to see someone drop the 17:1 down to say.. 12:1, get the turbo up to 50+lbs, add big honker injectors and maintain 15k on the system. ...........humm, what would happen? http://www.dieselplace.com/forum/smileys/HiHi.gif


BTW...... when the return fuel is "used up", what cools the injector?





Burner-------------&gt; http://www.dieselplace.com/forum/smileys/Big Smile.gif

No they are trying to fool you into thinking that 600 is achievable with stock injectors and a lift pump they are designing to sell. 600 with stock injectors and turbo without any other fuel source isn't possible.

Thanks Trippin, I'm catching on to this stuff. Thanks to so many of you knowledgeable people, in fact! I'm learning a lot.


I really have no doubts that a lift pump is a good idea. I'm a tightwad, but on the other hand I don't want to install a system that will later be inadequate. I'm all stock for now and will be as I wait to see who comes up with what for the LLY, performance mods-wise, especially the problems. It seems to me that if I installed something that gave me room to grow like the F.A.S.S. that I would be bypassing a lot of fuel back to the tank. Sure the fuel would be polished, but like I was implying I wonder about the effects of the heat.


I read what Kennedy said about the fuel cooler. I wonder if there would be a benefit to a better cooler for a truck that runs around southeast Texas 99% of the time, where winter lasts about 2 days. Cooler fuel will gas-off less. It would seem that warmer fuel would need to be boosted psi-wise more than cooler fuel. So I wonder just how significant the difference in heat exchange amongst the popular systems in their various applications. (If that makes any sense.)http://www.dieselplace.com/forum/smileys/Geek.gifAnybody ever thought of using a "cool can" like the gassers use? Or am I off base?

No they are trying to fool you into thinking that 600 is achievable with stock injectors and a lift pump they are designing to sell. 600 with stock injectors and turbo without any other fuel source isn't possible.


Your such a jerk!


I research, buy and design stuff for my truck. If other people like it and want it, great! If they don't, no big deal. I make a comfortable living at my day job. Which has nothing to with diesel powered trucks. This stuff is just a hobby. I'm not trying to fool anybody. Just exchanging theories with other people that share the same interest in Dmax trucks. Sometimes it's ok to agree, to disagree, yet you seem to always deal in absolutes without ever leaving open the possibilty that you could be mistaken. What will your position be if I can make "600 with stock injectors and turbo without any other fuel source"? I think it can be done. Just beacuse you haven't, doesn't mean it's impossible. As a community we all learn together. Relax, share your ideas, (I know you have some good ones) and maybe we all can learn something together. http://www.dieselplace.com/forum/smileys/Big Smile.gif

I read what Kennedy said about the fuel cooler. I wonder if there would be a benefit to a better cooler for a truck that runs around southeast Texas 99% of the time,


Anybody ever thought of using a "cool can" like the gassers use? Or am I off base?


John has some awfully good ideas/products. I enjoy talking to him. Half the stuff John has to offer isn't even on his web site. If you haven't,..... call and talk to him sometime, I guarantee you will learn at least one cool thing in each conversation with him.


I got to thinking about the cool fuel thing today, my first thought was ducting to the cooler to make sure we direct air through it at speed and then maybe an auxillary fan for traffic or idle situations. Perhaps a small flat electric or maybe an inline blower like a circle track car uses to cool the driver/brakes.

I read somewhere that SuperTanks had a replacement fuel line with fins on it for applications where the factory cooler is removed.


It would seem that if you have enough pump you could push through another 10-feet or so of fuel line in a canister type cooler. Off hand I cannot think of a good or conventional place to mount it. I think first I would try the finned fuel line---maybe a section for the bypass line back to the tank and an run off of the discharge of the pump. I know there is a way to drop that temperature...just need to figure if it's worth the effort.


Any opinions on the AirDog? I like that it supposedly hangs down a little less than the F.A.S.S.


BTW, I've talked to Kennedy via e-mail and a couple of others here. Nice folks...teachin' me a lot!http://www.dieselplace.com/forum/smileys/Big Smile.gif


Edit: Well, that sucks...after looking at the SuperTanks parts list it appears that the finned fuel line is 3/8. I still think there are a lot of options. Instead of coiling 1/2 fuel line in a can, wrap it with 3/8 aluminum fuel line and then you have an exchanger. Or simply run the 1/2 line through another 2 inch or so line, plumbed up to a circulating pump and coolant surge tank. I would guess that any kind of air cooler will need plenty of surface are to be effective---that might mean a pressure drop in the fuel system.Edited by: T-Rex

With all the fuel flow and pressure without high efficiency additional filtering ,what happens to the Factory Racor with a flow rating of only 48 GPH and dirty fuel ??





Mac

First off a reasonable lift pump is a good idea for several reasons but not for more hp out of an otherwise stock fuel system. I have made more hp than most with a Duramax and did that in front of several at an event and not off in the corner of a shop by myself, I also made big hp without a lift pump. GM giving us a system that will make around 500 hp without any modification is great but at that level several thing if not the whole system are overworked. Trying to band aid the system with a lift pump that flows a ridiculous amount like 180 gph isn't going to help anything. You need to start with the biggest problem at this point which is the injectors. We are already stretching the injector pulse far enough to be injecting fuel at less than desirable times. We have already found that the Duramax with stock injectors and turbo will make just over 500 and no amount of fuel shoved to the to the stock system is going to make much improvement. You just can not pass any more fuel through the stock injector in a timely manner. Then when you do add injectors and allow the pump to get more fuel into the cylinder you are for the most part already out of air with the stock charger so you need to upgrade that also. When you do upgrade injectors and airflow then it is going to require different programming to make that equipment work efficiently. It is going to be expensive to get to the 600 hp range but a fuel pump big enough to supply a 1000hp gas engine will not help enough to be worth the cost before or after injector and turbo upgrades. You need to realize that the stock system moves less than 20gph and still will generate 500 rwhp ( it has been done by several people) so why on earth would you think you would need a pump over 50 or so gph to maintain 600 rwhp? The motor isn't going to use that much more fuel so if you can't maintain pressure then you must be returning way to much. Maybe you need to work on getting the fuel these reasonable size pumps generate to the right place instead of sending it back to the tank?


Basically if you need more power than you get from a good stack of programs then you are going to spend a lot of money to get to the next level. GM really made it easy and reasonably cheap to get up in the high 400 rwhp range compared to what was available in the past and other brands but to go to 600 rwhp is going to seperate the crowd. I'm sure there are some trucks out there that have issues of some sort that may show big hp improvements but it has to be a small percentage because I have dyno tested several trucks and haven't found one that made any extra hp with a lift pump and yes I have some big lift pumps.





Craig- if you know something or have tried something that seems to work for you, then spill the beans. http://www.dieselplace.com/forum/smileys/Geek.gifI mean thats what we're here for to share info and help everyone out. If i had any insight i would add to the knowledge here, but i don't because i have a bursting issue with some of the programming that i am using, and a small problem with all the other different programming, and of coarse injectors thrown in there too. So this thread is very interesting to me, as i hope what comes of it will solve my problem.


There is alot of good and valid points in this thread, at least thats my opinion that seems to point to fuel flow, now you have a different feeling or opinion about it, but i/we need examples or such to validate or digest them. I'm not trying to be a dick, but just looking to see your side or your take on it, with some hard facts or examples.Edited by: heartbeatcanada

First off a reasonable lift pump is a good idea for several reasons but not for more hp out of an otherwise stock fuel system. I have made more hp than most with a Duramax and did that in front of several at an event and not off in the corner of a shop by myself, I also made big hp without a lift pump. GM giving us a system that will make around 500 hp without any modification is great but at that level several thing if not the whole system are overworked. Trying to band aid the system with a lift pump that flows a ridiculous amount like 180 gph isn't going to help anything. You need to start with the biggest problem at this point which is the injectors. We are already stretching the injector pulse far enough to be injecting fuel at less than desirable times. We have already found that the Duramax with stock injectors and turbo will make just over 500 and no amount of fuel shoved to the to the stock system is going to make much improvement. You just can not pass any more fuel through the stock injector in a timely manner. Then when you do add injectors and allow the pump to get more fuel into the cylinder you are for the most part already out of air with the stock charger so you need to upgrade that also. When you do upgrade injectors and airflow then it is going to require different programming to make that equipment work efficiently. It is going to be expensive to get to the 600 hp range but a fuel pump big enough to supply a 1000hp gas engine will not help enough to be worth the cost before or after injector and turbo upgrades. You need to realize that the stock system moves less than 20gph and still will generate 500 rwhp ( it has been done by several people) so why on earth would you think you would need a pump over 50 or so gph to maintain 600 rwhp? The motor isn't going to use that much more fuel so if you can't maintain pressure then you must be returning way to much. Maybe you need to work on getting the fuel these reasonable size pumps generate to the right place instead of sending it back to the tank?


Basically if you need more power than you get from a good stack of programs then you are going to spend a lot of money to get to the next level. GM really made it easy and reasonably cheap to get up in the high 400 rwhp range compared to what was available in the past and other brands but to go to 600 rwhp is going to seperate the crowd. I'm sure there are some trucks out there that have issues of some sort that may show big hp improvements but it has to be a small percentage because I have dyno tested several trucks and haven't found one that made any extra hp with a lift pump and yes I have some big lift pumps.





I guess this is what I've been trying to say for quite some time. To really exceed 550 HP and get to the next level a larger lift pump would be beneficial but not as a stand alone item. Fuel delivery/Pulse width will only take you so far. Larger injectors to bring up turn down rates and a lot more air etc.,etc. would be needed. Possible displacement increases ????? We have only been through the easy part and now to get a little more a lot more will be required. I feel fortunate that we are able to get to the 500+ HP mark with very little mods cost and labor wise. Going further will come at a sugnificant cost and fuel mileage would start to suffer accordingly for every day driving. I guess I've been speaking for the majority here but failed to realize that some want to go beyond and don't mind doing what it takes to get there. However there will be a price to pay along with a expected decrease in engine life to take things to the next levels. May the power be with those who desire it. From this point on I guess I will be a spectator but will remain very interested and excited to see the numbers this engine can deliver. Edited by: a bear

Thanks Trippin, I'm catching on to this stuff. Thanks to so many of you knowledgeable people, in fact! I'm learning a lot.


I really have no doubts that a lift pump is a good idea. I'm a tightwad, but on the other hand I don't want to install a system that will later be inadequate. I'm all stock for now and will be as I wait to see who comes up with what for the LLY, performance mods-wise, especially the problems. It seems to me that if I installed something that gave me room to grow like the F.A.S.S. that I would be bypassing a lot of fuel back to the tank. Sure the fuel would be polished, but like I was implying I wonder about the effects of the heat.


I read what Kennedy said about the fuel cooler. I wonder if there would be a benefit to a better cooler for a truck that runs around southeast Texas 99% of the time, where winter lasts about 2 days. Cooler fuel will gas-off less. It would seem that warmer fuel would need to be boosted psi-wise more than cooler fuel. So I wonder just how significant the difference in heat exchange amongst the popular systems in their various applications. (If that makes any sense.)http://www.dieselplace.com/forum/smileys/Geek.gif


Anybody ever thought of using a "cool can" like the gassers use? Or am I off base?





Fuel cooling will be most effective with greater temperature differential. That is why they use the return line. I think a first step may be to try a thermostatic fan on the cooler.





I don't know how hot the cooler gets in southern states. May want to monitor it. You can monitor the engine "out" temp of the fuel on a scan tool. which should give you a good idea...

I understand were you are coming from on all the above but am still a bit fuzzy on a few things…..


Say the cavity is being only .5 way filled then what is filling the rest of the cavity? It must be a gas right? You cant compress diesel and you allso cant "strech" it right?


I’m also not questioning if something works or not…..I could care less right now, I’m just wondering why. I’m saving putting stuff into the “right and wrong” boxes latter, I’m just out collecting info now.


Interesting stuffhttp://www.dieselplace.com/forum/smileys/Thumbs Up.gif








If you filled a cylinder with liquid and no air, and expanded the cylinder (pull out on the piston), the piston will rise. What is in the "gap"? Low pressure vapor that has out-gassed from the liquid. It is not air, nor is it a vacuum. Fuel will out-gas in a vacuum.


So at least in theory, you could have a gerotor pump only pushing 50% volume due to out-gasing at low pressure. Does it happen? Hell if I know, but this is an interesting thread, even if you don't want 600hp.





Dooby dooby doohttp://www.dieselplace.com/forum/smileys/Geek.gif.......any more thoughts on thishttp://www.dieselplace.com/forum/smileys/Confused.gif

With all the fuel flow and pressure without high efficiency additional filtering ,what happens to the Factory Racor with a flow rating of only 48 GPH and dirty fuel ??





Mac





Unfortunately, I think the stock filter/mount may have to be bypassed to make the big power. So far I can hold line pressure after the stock filter, and we have made the stock filter flow more by adding pressure to it. I wonder what pressure the 48gph is rated at? The FASS/Prep have water seperators, so that is not a concern. A "high efficiency" "high flow" filter for the lift pump is on it's way to us for testing.

No they are trying to fool you into thinking that 600 is achievable with stock injectors and a lift pump they are designing to sell. 600 with stock injectors and turbo without any other fuel source isn't possible.


Your such a jerk!


I research, buy and design stuff for my truck. If other people like it and want it, great! If they don't, no big deal. I make a comfortable living at my day job. Which has nothing to with diesel powered trucks. This stuff is just a hobby. I'm not trying to fool anybody. Just exchanging theories with other people that share the same interest in Dmax trucks. Sometimes it's ok to agree, to disagree, yet you seem to always deal in absolutes without ever leaving open the possibilty that you could be mistaken. What will your position be if I can make "600 with stock injectors and turbo without any other fuel source"? I think it can be done. Just beacuse you haven't, doesn't mean it's impossible. As a community we all learn together. Relax, share your ideas, (I know you have some good ones) and maybe we all can learn something together. http://www.dieselplace.com/forum/smileys/Big Smile.gif You can name call all you want I was just trying to bring some of you back to reality. If you can't understand why injecting more fuel through the stock injectors at the durations we are alreay using then I guess you should keep trying. I never said anything you or others have done is a bad thing, what I said was it wasn't cost effective or going to achieve what you are looking for period.

Boy this is fun. http://www.dieselplace.com/forum/smileys/Wink.gif Turbo efficiency map really doesn't mean squat. Just the number of psi that it's starts producing more heat than they think it should (usually 330*). Run em!!! The only real number we need is what boost (as in what turbine R's) the compressor wheel splits at.


You obviously dont know much about turbos. http://www.dieselplace.com/forum/smileys/Evil Smile.gif


As for the lift pump situation vs. the guy who claims the injectors is the end to all problems. What you have to realize is that nobody has claimed the lift pump is the final solution. What we are trying to say is that there is a fuel delivery problem and the lift pump is the most logical inital step. Maybe it fixes alot more then we thought, maybe not but you have to build a solid foundation in order to work your way to the top.. I'm sure Steve isnt building an entire pump assembly b/c he hopes it will work. He has spent more R&amp;D on the dyno testing these issues then probably most of you combined. I understand I am taking sides here, but thats only b/c I know how much time he has invested into the analysis of the ENTIRE fuel system (inspecting and tearing apart each and every component from the gas tank to the combustion chamber) He has real life data, not speculation and it proves exactly what he is trying to say.


We have proven there is a lack of fuel flow on big programs which is causing a vacuum condition in the gas tank, and as a result lowers the volume of fuel being delivered to the HP pump, which directly has an effect on the rail psi.. We have also proven that as we run larger pumps and move more volume, the pressure to the HP pump is more consistant, and rail psi does NOT drop. I may be completely wrong but i dont see injectors doing a whole lot of good if you cant get the fuel there in the first place.


I'm sure we will get to a point where we stumble across other hurdles as the horsepower levels are increased. May be the fuel line ID next, maybe the inlet to the suction pump, maybe the internals of the hp pump, then maybe the injectors. But in order to start diagnosising a problem it is only logical you work forward not backwards. That means addressing the intank pickup, then the lift pump, then forward to the HP pump, etc.


You can stick to your own beliefs, but you cant dissagree with the fact that fuel pressure is dropping due to a SUPPLY issue.

First off a reasonable lift pump is a good idea for several reasons but not for more hp out of an otherwise stock fuel system. I have made more hp than most with a Duramax and did that in front of several at an event and not off in the corner of a shop by myself, I also made big hp without a lift pump. GM giving us a system that will make around 500 hp without any modification is great but at that level several thing if not the whole system are overworked. Trying to band aid the system with a lift pump that flows a ridiculous amount like 180 gph isn't going to help anything. You need to start with the biggest problem at this point which is the injectors. We are already stretching the injector pulse far enough to be injecting fuel at less than desirable times. We have already found that the Duramax with stock injectors and turbo will make just over 500 and no amount of fuel shoved to the to the stock system is going to make much improvement. You just can not pass any more fuel through the stock injector in a timely manner. Then when you do add injectors and allow the pump to get more fuel into the cylinder you are for the most part already out of air with the stock charger so you need to upgrade that also. When you do upgrade injectors and airflow then it is going to require different programming to make that equipment work efficiently. It is going to be expensive to get to the 600 hp range but a fuel pump big enough to supply a 1000hp gas engine will not help enough to be worth the cost before or after injector and turbo upgrades. You need to realize that the stock system moves less than 20gph and still will generate 500 rwhp ( it has been done by several people) so why on earth would you think you would need a pump over 50 or so gph to maintain 600 rwhp? The motor isn't going to use that much more fuel so if you can't maintain pressure then you must be returning way to much. Maybe you need to work on getting the fuel these reasonable size pumps generate to the right place instead of sending it back to the tank?


Basically if you need more power than you get from a good stack of programs then you are going to spend a lot of money to get to the next level. GM really made it easy and reasonably cheap to get up in the high 400 rwhp range compared to what was available in the past and other brands but to go to 600 rwhp is going to seperate the crowd. I'm sure there are some trucks out there that have issues of some sort that may show big hp improvements but it has to be a small percentage because I have dyno tested several trucks and haven't found one that made any extra hp with a lift pump and yes I have some big lift pumps.





Craig- if you know something or have tried something that seems to work for you, then spill the beans. http://www.dieselplace.com/forum/smileys/Geek.gifI mean thats what we're here for to share info and help everyone out. If i had any insight i would add to the knowledge here, but i don't because i have a bursting issue with some of the programming that i am using, and a small problem with all the other different programming, and of coarse injectors thrown in there too. So this thread is very interesting to me, as i hope what comes of it will solve my problem.


There is alot of good and valid points in this thread, at least thats my opinion that seems to point to fuel flow, now you have a different feeling or opinion about it, but i/we need examples or such to validate or digest them. I'm not trying to be a dick, but just looking to see your side or your take on it, with some hard facts or examples. Hard facts and examples? Everyone that has run programming that burst (because the program calls

Boy this is fun. http://www.dieselplace.com/forum/smileys/Wink.gif Turbo efficiency map really doesn't mean squat. Just the number of psi that it's starts producing more heat than they think it should (usually 330*). Run em!!! The only real number we need is what boost (as in what turbine R's) the compressor wheel splits at.


You obviously dont know much about turbos. http://www.dieselplace.com/forum/smileys/Evil Smile.gif


As for the lift pump situation vs. the guy who claims the injectors is the end to all problems. What you have to realize is that nobody has claimed the lift pump is the final solution. What we are trying to say is that there is a fuel delivery problem and the lift pump is the most logical inital step. Maybe it fixes alot more then we thought, maybe not but you have to build a solid foundation in order to work your way to the top.. I'm sure Steve isnt building an entire pump assembly b/c he hopes it will work. He has spent more R&amp;D on the dyno testing these issues then probably most of you combined. I understand I am taking sides here, but thats only b/c I know how much time he has invested into the analysis of the ENTIRE fuel system (inspecting and tearing apart each and every component from the gas tank to the combustion chamber) He has real life data, not speculation and it proves exactly what he is trying to say.


We have proven there is a lack of fuel flow on big programs which is causing a vacuum condition in the gas tank, and as a result lowers the volume of fuel being delivered to the HP pump, which directly has an effect on the rail psi.. We have also proven that as we run larger pumps and move more volume, the pressure to the HP pump is more consistant, and rail psi does NOT drop. I may be completely wrong but i dont see injectors doing a whole lot of good if you cant get the fuel there in the first place.


I'm sure we will get to a point where we stumble across other hurdles as the horsepower levels are increased. May be the fuel line ID next, maybe the inlet to the suction pump, maybe the internals of the hp pump, then maybe the injectors. But in order to start diagnosising a problem it is only logical you work forward not backwards. That means addressing the intank pickup, then the lift pump, then forward to the HP pump, etc.


You can stick to your own beliefs, but you cant dissagree with the fact that fuel pressure is dropping due to a SUPPLY issue.





Quit talking about it and prove it then. We are already injecting fuel @ maximum psi for too long during the stroke and that is inefficient. With injectors the hp pump will pass more fuel easier and will be able to get it in the cylinder when it can be used. But your welcome to waste your time trying if you want to.


p.s. I didn't say the injector was the end all, only that it was the next step so if you want to work backwards?Edited by: CPMac

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<TD class=text>Boy this is fun. http://dieselplace.com/forum/smileys/Wink.gif Turbo efficiency map really doesn't mean squat. Just the number of psi that it's starts producing more heat than they think it should (usually 330*). Run em!!! The only real number we need is what boost (as in what turbine R's) the compressor wheel splits at.</TD></TR></T></T></T></TABLE></TD></TR></T></T></T></TABLE></TD></TR></T></T></T></TABLE>


"You obviously dont know much about turbos. http://dieselplace.com/forum/smileys/Evil%20Smile.gif "


Um, alrighty then. I'm not gonna comment on that for obvious reasons, and I'm done with this post now. Don't you think you should find out who I am and what I've done on the last 1,458 engine designs and overhauls before such a blanket statement. Build whatever you want and I'll do the same like always. No biggy. I will say that I've learned from every single post on here, like always, and only helped out or answered questions that I know to be true thru my own testing and enecdotal evidence. If you didn't notice, this kinda s#&amp;t is my job, and 17 years in business might equate to some scenarios you may not have run into. There must be a severe coffee shortage on the left coast. Sorry to here that. Anyway, good luck either way. Later kids. I'm out...T Edited by: ynot

You obviously dont know much about turbos.





The whole turbo issue is way seperate from this stuff but why do you say that? Just curious why you dissagree. No offense ment but your comment provided me absolutly no info, weather his info was right or wrong is irrealivent. If you think its wrong please explain since we are all here to learn and just saying you dont know what your talking about dosnt help IMO. No flame inteneded