I am going to have my injectors done in the next couple of days if i can get into a shop and would like a recommendation from some of you guys as what to purchase to put in the 2000 truck. I will be getting a chip ASAP also.


So the question is, hi flow or hi pops? Whats the diffference and who's should i get (brand name?), I know they can be purchased through Kennedy or Heath but i'm affraid they would never get here to Alberta in time, i'm taking a week off of work to do this starting the end of today and every day i'm down i'm losing big $$$.

DAS comes to mind, A google search is always a click away.

It sounds like your going to sink a grand into this truck this week.


What's another $50 for Next Day Air from a Vendor.


I think I would go with JK's...


A lot of people seem to have good luck with them.





On Edit: Hi Flow/Hi Pop. No Question...Edited by: Billman

If i can get parts i will be sinking in probably close to 2 grande. $50 for next day air is no problem.


I just got a quote for $770 Canadian for hi-flow/hi pops, suppose to be a 25 horse increase. Not sure if thats a good price or not compared to Kennedy's in US dollars.


Looking into BD diesel right now to see some pricing.


http://www.bd-power.com/gmc/index.php

dsg (diesel services group) out of canada has bosch high outputs for 78 a piece times 8 equals 624, then there is a discount so it comes out to $595 canadian. ($498 american)


http://www.dieselservices.com/webstore/moreinfo.cfm?Product_ ID=58&CFID=117764&CFTOKEN=52509911 (http://www.dieselservices.com/webstore/moreinfo.cfm?Product_ID=58&CFID=117764&CFTOKEN=525 09911)


Edited by: steiner43511

CR,


I'm jealous. Performance (marine) injectors are on my Santa list. There are two kinds of injectors for the 6.5TD...standard and the marine version. The marine version are both high pop and high flow. I'd go with Bosch and if you can get them for $595, I'd jump on that deal.

Hey guy's thanks for the info and support. I've just found a guy thats about 1 hr from my house that can get me all the parts i need and probably can have a mechanic do it for me also. He also knows a local guy that programs the ECMs too and sounds pretty darn cheap!


Please do me a favor and check this guys site out!


http://www.uglytrucksplus.com

Hi pop injects at higher pressure - get better spray pattern, better combustion, more efficient.


Hi flow allows for more fuel when pump is turned up.


Both do so across the band - idle to power.


Hi flow-hi pops can cause some problems with low and erratic idle rpm, where PCM cannot manage cylinder balance.Edited by: gmctd

Booked in to install a programed PCM on Thurs. Then the guy will tune it for the truck, still waiting to here back from this other guy on getting me the hi-pops! Can hardly wait to be able to change the sig line now!

Hi flow-hi pops can cause some problems with low and erratic idle rpm, where PCM cannot manage cylinder balance.


gmctd,


Could the situation you describe be directly related to those "reengineers" who will raise pop pressure to some level beyond the manufacturer's spec?

I got a set of Marine injectors here. Looked to be the best price I found. Also has a ton of other goodies for the 6.5.


http://www.ssdieselsupply.com/category_12_Performance.html (http://www.ssdieselsupply.com/category_12_Performance.html)


I got the FSD kit and 4" exhaust as well. Next will be the Cooling system upgrade.

Good question, spindrift -


Pcm manages idle speed by determining inertial variances in 64 slot\cylinder hi res optic output - this is based on factory equipped injectors and fuel rates.


PCM can vary fuel rate and timing on per-cylinder basis to maintain smooth idle, stable idle rpm.


The DS-4 EFI system is a constant-beginning, variable ending injection system, as referenced to the camring.


Injectors are calibrated for a specific opening pressure, or 'pop' pressure, and as such, set the system injection pressure.


As n\a injectors 'pop' at 1500psi and turbo injectors 'pop' at 1700 psi, I would assume some difference in the PCM timing and fuel rate programming for each engine type, to compensate.


If higher pressure injectors are installed, actual time of injection within the window set by the PCM is delayed while pump is developing additional pressure required to 'pop'.


This 'retarded' injection timing can be offset with timing adjustments - more on this, later.


Higher inj pressures result in finer fuel atomization for improved combustion - more power.


But, it is also harder on the camring and rollers in Inj Pump, resulting in accelerated wear due to increased hydraulic loading.


Hi flow injectors have larger injection orifice\nozzle, allowing more fuel thru-put.


This can result in more fuel in cylinder, earlier in the inj window set by the PCM.


These improvements - higher pressure, more fuel - are mechanical, and as such occur across the rpm band, idle to full output.


But, the PCM can not measure that these things have occured - all it 'knows' is that GM-spec 1700psi requires "x' time to meet programmed fuel injection rate between start - Fuel Solenoid closure - and end of injection window - FS off, rotor heading for next cylinder.


Hi-flo hi-pop injectors allow greater output power - but PCM can have some little problems in managing idle rpm and stability.


It's a trade-off, not always managed very well in 6.5 EFI system, but can easily be compensated for with the mechanical inj pump - simply adjust the throttle shaft stop-screw to obtain desired nirvana.


The injectors were set up for marine use, where the mechanically-injected Diesel engines are usually at some percentage of full throttle, stokin' the cap'n's yacht thru the Florida keys.


In short, and to wit, spin - yes.


That's my story, and I'm stickin' to it...............Edited by: gmctd

So this 'Retarded Timing' will become worse with a worn timing chain.


Will the advance that's built into the Gear Drive help this delay of injection?

It is compensated for by advancing base timing and increased TDC Offset adjustment - more on that, later.


These timing changes are required for any power increase, and must be done in conjunction with marine injector installation in EFI systems.


The ~2deg advance of the DSG set is also result of no timing chain slop - even new chain sets have some play.

jd...I'm with 'ya to a point. Let's assume you have a truck that is either chipped or is running a Mega ECM. I would imagine that all of this new programming that is out on the market is designed to exact maximum fuel delivery out of our DS-4. If the ECM is requesting a delivery rate of say, 80 mm3, wouldn't the "hi flo" component of a hi flo-hi pop injector be neutralized? Meaning, the injector can't provide if the ECM says "No", regardless of orifice size. I understand where you would gain more power from the hi pop component as that would give you the better spray pattern and better combustion.


So, the million $ question for me is whether or not we're installing these HO injectors while ignoring whatever blueprinting could be performed on the injector/ECM relationship (does that make sense?). Wouldn't you then see your greatest efficiency and MORE POWER?

I have 10 injectors I took off these trucks and have yet to have them tested. Would it be a better investment to buy new marine injectors or have new nozzles and 1800 pop presssures done at a local fuel shop on these used ones?

Possibly TDG or Dieselpro will offer injector flow specs here, but basically, the difference is comparable to flowing liquid thru a 1/4" pipe as compared to a 3/8" pipe.


The larger diameter offers less restriction to all flow, while allowing more flow as required.


Same thing applies to the injector pipes - when converting to the mechanical DB2-4911 Inj Pump, the '90 6.2L pipes may fit and will flow, but the '92-'93 turbo 6.5L pipes were upgraded for the higher output capability.


Far as purchased vs rebuilt injector decisions, I'd say let cost be your guide.


Just determine if they grind and lap the old nozzles or install new nozzles for the rebuild - empirically, the new nozzles are more reliable.


May be a further caveat here, depending on professional input from TDG or Dieselpro.

You might try these guys, Cowracer got a set from them and he seems to think they are good.


http://dieselhelp.com/gmc-2.html#injectors

I bought my bullydog down pipes from them.


$375USD for a performance set.


$375 for A DB-2 rebuild.

High Flow? The pump puts out a regulated quantity of fuel. How can the injector flow more than the predetermined amount of fuel?


Hi-Pop? If you increase the pressure, want you also decrease the volume and delay injection? Will this pressure cause premature wear? Seems low pressure will reduce load, increase volume, slightly advance timing.


High flow injectors are just the same injector body with a different tip. Usually a tip thats cheaper than the original. We need a tip number. Anybody want to tear their hi-flow down and get us a number off the tip?


Hi-Pop - These are just injectors that have been shimmed up a bit to increase pressure. Quite simple. 100-200 PSI over specs won't hurt but I doubt if you would notice it at all. It certainly won't increase the power.


Nobody said anything about spray pattern. Think all 6.2-6.5's have a zero degree pattern. That means the fuel sprays straight out. Think some of the "hi-flow jobs are using a 12 degree pattern. Maybe you should be talking spray pattern.


Spray pattern would be critical in a prechamber. Really depends on a lot of factors


Planning on flow testing some this winter. Will post some results on quantity of different nozzles and volume related to pressure changes.


Personally like the New Delphi nozzles. Check with Napa. Their rebuilt 6.5 injectors are NEW Delphi if they have green caps on them. Insider info, please don't tell anyone.

I have a set of JKs HO injectors which he says are both set for hi pressure and high pop, I don't know the numbers, may pull a couple out and have them checked, as JD detailed they do mess with low end idle and when cold noisy as heck; if I bump up the idle to 750 rattle goes away, my normal idle hovers around 600rpm when I 1st start up, they have been in about a year now, and work well with the Heath reflash.


I'm thinking the instability at low end is as JD pointed out changing orifice size and pop pressure is something the PCM is blind to and is there at all speed ranges,


I'm flowing a little more fuel than what PCM is expecting, unplug my MAF sensor and it gets really bad I look like a fogger truck (remember I'm L56 rigged working on a solution for that).


Bill Heaths hiflows may be better tuned to his reflash I don't know. Rattle is something I don't hear anymore JD had me worried earlier in the year when I stopped by for a visit and he thought my truck sounded lto him like it was having problems. 2 satisfactory oil samples and 7000 miles later the truck is still in one piece.

TD,


I think there is at least the possibility that the pop pressure of your injectors has been set beyond the specs of the manufacturer, which may be contributing to the rattle at low end idle and cold conditions.


The ECM is blind to injector flow and pop pressure. The ECM only knows what it has requested; which tells me that the ECM should be programmed to be in sync with the specs of the HO injector. And then you have a well-tuned truck. I think.

Thanks for the input,Dan - I will be interested in the results of your injector tests.


My post was about increased fuel atomization with increased injection pressure, but have no data on what pressure the hi pops open at, or if that pressure increase effects spray pattern.


If they are standard injectors with stiffer spring rates, then pressure increase could disrupt spray pattern.


If they are an integrated package, oem could have also changed pintle\nozzle profile to compensate.


Your tests will tell the tale.


What about you, TDG - any specs available on the 1500 and 1700psi injectors, compared to hi flo and\or hi pops?

All GM injectors use a Zero degree spray angle. The pattern does not change with pressure increases. The Zero angle means it sprays straight out from the nozzle whereas some spray out at a slight angle, like an inverted cone. The naturally aspirated engines pop at 126bar./1827 PSI. The turbo injectors pop at 142bar/2060 PSI. The pressure is adjusted by adding or subtracting shims. A shim thickness of about 0.002" equals ~100 PSI.


Early 6.2's O SD248 nozzle 126 bar.


Short Body 6.2's OSD253 nozzle 126bar.


All 6.5's & nbsp; OSD304 nozzle 126bar. (turbo popped at 142 bar)


Next: How to make a pop tester out of a cab Jack.

Cabjack?

Ok - 1 bar = 14.69psi


Got math, anyone?

Nope got conversion check out this site


http://www.onlineconversion.com/ (http://www.onlineconversion.com/)

Thanks


And thanks for the numbers, Dan -


How does GM spec at 1500psi n\a and 1700psi turbo relate to 1827psi and 2068psi 'pop' pressures?


And can you define 'pop'?


And, that's the second time I've seen "& nbsp;" on here, representing what?


What am I missing?Edited by: gmctd

Pop pressure is the pressure at which the injector opens or starts to spray. ( & nbsp;) I didn't type that. Must be some glitch in the system.


Have made pop testers out of Cab over hydraulic jacks.

Stock 6.5 injectors set to 142 bar.


Bosch HO (marine) set to 150 bar.

So - GM spec is either wrong or indicates min pressure.............


And Bosch is 2205, ~150 over turbo max.


Hydraulic jacks, huh - sounds interesting.Edited by: gmctd

My old truck buddy told me when he bought a truck (way back when)with a Buda engine in it they came with a pop tester in the cab of the truck. It was a Buda tester and it looked like a hydraulic jack with no ram. I have seen them on ebay. Any high pressure hydraulic, pump up system could be converted to pop an injector as long as it can create 5,000 psi with diesel fuel in it. Don't think hydraulic fluid would work to well.


The injector doesn't pop. It chatters if it's working well.

Kinda hard to explain to someone that doesn't have pop tester experience...


Testing injectors usually consists of these criteria


opening pressure, slowly build pressure and watch on the gauge when the nozzle opens and releases pressure. Low opening pressure will reduce nozzles effectiveness, too high and it will wear out the nozzle.


chatter, when the nozzle does open, it should open and close very rapidly, this keeps pressure at desired level and improves spray and atomization characteristics. Poor chatter is often cause by fuel contamination, stains or worn valves.


spray pattern, as Dan said, injectors vary a lot, for the most part, prechamber injectors are pintle style and the spray pattern is designed to shoot down the chamber towards the piston. On a direct injection engine, the injector is directly above the piston and several ports will direct the spray in a 'star' pattern horizontally from the nozzle. Faulty injectors can spray only or more on one side than another or have plugged ports.


atomization, all fuel coming from the nozzle should be in a fine spray, diesel injectors are actually capable of destroying molecules there by 'atomizing' the fuel, which helps combustion. poor atomization causes rough idle/ white smoke and hard starting.


and finally leakage, excessive leakage means sealing surfaces inside the injector are worn and need to be refaced or replaced as needed, this leakage reduces overall fuel delivered to the engine and mostly causes power or balance problems.

Go here and go down the page to see a hombrew injector tester


http://www.mercedesshop.com/shopforum/showthread.php3?t=9664 (http://www.mercedesshop.com/shopforum/showthread.php3?t=96648) 8

Might use caution in using diesel fuel in a cheap bottle jack. The diesel might play havoc with the seals. Save the seals!


I always jack my injectors up when I build them. Jack of all trades. If you jack them up to high you'll need to put jack stands under them. What type fluid would you use? I think power door lock fluid would work great! It's colorless, odorless, and cheap. Stay away from power window fluid as it takes on a tint with age.

Ok - it all makes sense (even got a 'window' on the humor, Danhttp://www.dieselplace.com/forum/smileys/smiley36.gif).


So - what's with the GM spec? Error, misprint, or min pressure at max wear?


And thanks for the input, guys.

Not sure I follow. Are you referring to the GM spec for pressure? Specs for pressure seem to agree at 142 bar.