For those of us out there who have seen 6.5 heads off the truck, did you ever notice how the glow plug sticks right in the middle of the prechamber? I'm sure everyone has had problems with them burning out, but what if they werent there? Wouldn't that allow better injection spray through the chamber, as well as drop compression? What if you just removed the glowplugs completely and just put blank pipe plugs in their place, and using the stock glowplug controller just had it operate an air intake heater like the Dodges have instead? Anyone think this is a good idea? see a major flaw in it?

Sounds like a great idea. I see no reason it won't work. In the summer time the 6.5 will start with out using the glow plugs. The real test would be in the winter.

intake heater should work, compression is a lot higher in the 6.5s than it is in the dodges that start fine with that system.Edited by: Texas Diesel Guy

Worth a shot! Last year half my glows were bad, and hadn't changed them yet. I could stick a hairdrier in the intake, and would cut the time in half to start the engine.

I think you're on to something. How much would an air heater cost from a junk yard?

You're gonna need ether...

The one that powerstrokes use might be the best fit...right into the intake tube from the turbo, I'm gonna try it out, I'll see if I can find a good used one...

Well after my trip to the hardware store and not finding a small enough pipe plug...perhaps the best way is to find a machine shop with a head already off the engine so I can measure how much to chop off the end of the glow plugs to keep them out of the prechamber, and just put them back in the holes unplugged. I'm pretty sure I can mount 2 intake heaters, one on each side of the manifold both powered by the factory relay, and that should be sufficient to start this puppy.


I really hope this is as successful as I'm hoping it will be, on these engines when that piston is at TDC, I'd guess more than half of the total combustion chamber volume is in the prechamber, and the rest is actually between the piston and head. Cleaning up this critical area and expanding it should allow more boost to be introduced and create a cleaner burn.Edited by: Texas Diesel Guy

Isn't it just 1/8" NPT? That is the fitting size I used when piecing a compression tester together.


Also, you have to remember that it will take more heat to start with the lower compression. There probably isn't any way to figure out what the actual compression ratio will be is there?


How soon do you think you will get it finished? Sounds very interesting.

Yeah, it is, but Home Depot doesnt carry them, atleast not in steel, and I dare not trust brass, and I can't do it until I get a pair of intake heaters....I'm not starting it with ether


man I wish I had that Flowmaster downpipe and crossover here...Edited by: Texas Diesel Guy

It it hot down there isn't it? Just pull the glowplug fuse and see how hard it starts. Maybe you could get by till winter with no heater.

Home Depot? Isn't there anywhere else around there? They get at least twice as much for any pipe fitting around here as Menards or Farm & Fleet. (they have a different brand so they don't have to honor the 10% guarantee)

TDG


By removing the GP's and lowering CR, you now want to add more boost.


How much more boost are you going to add to this 'Self Defeating Sysyem'. With more boost = more blowby(You say), even with your dual breather set-up, you're going to heat the intake air.


Now you need an Intercooler. Or somehow cool the Intake Charge.


But if I remember correctly, you claimed comparitive power with 7 psi to someone who is pushing 17 psi.


Why do you need more boost now? Just curious...

Ahem...I said more boost means more blow-by on a high compression ratio engine, which the point of removing the glowplugs is to drop compression, lower blow-by and increase boost tolerance. The advantage to the dual breather setup is blow-by volume doesn't matter anymore.


Other than that your right, yes if I increase boost considerably, an intercooler would certainly be beneficial.

How much will the comp. drop by removing the glow plugs?

I don't recall you saying more blow-by in a 'Hi Compression Engine'.


But if you say so...


By removing the glow plugs, do you think you will lower CR to 20 to 1? 19 to 1? How much less blow-by with such a small decrease in CR?


I'd love to see you on a dyno - before and after your miracle breather theory. I'd expect worse numbers after the mod. With the little vacuum that is created in the crankcase with the CDR in place more than makes up for the 'Dirty Air' that is ingested.


Vacuum in the crankcase makes Horsepower. Professional Engine builders run a Vacuum Pump to pull 15-20 in. and make considerable gains. The bigger the cubic inches and oil pan, the more power is made. Typical gains are in the 20 HP range.


I'm laughing at everbody still running out to buy breathers. Actually I think they are doing more damage than good.


I understand that you're trying to help, so excuse my sarcasm.


The Ass-Dyno is not a valid source of info.

Billy, I don't run any breathers but I did remove the hose that went from the CDR to the intake duct and ran a hose out down under the truck. I don't like the hot air running into the intake. I got the idea from a Ford guy.
It makes no more power but maybe it runs cleaner and a little cooler. By the way I did this about 2 years ago.

Joey


I remember reading somewhere(maybe here) about you doing just that. Actually I thought you said you were putting it in the exhaust POST-TURBO.


Now I think THAT would be beneficial. Keep the intake clean, yet help the crankcase a little.


Long before the vacuum pumps came around, everybody used the Moroso crankcase evacuation system. It pulled 1in if you were lucky.Edited by: Billman

Bill, I just reviewed the comments you were referring to that I made in the WMI vs. IC thread, and I not only mentioned the compression issue specific to these engines, I also stated that if we were talking about any other diesel I would totally agree with what you guys are saying. The goal of removing the glowplugs is not to reduce blow-by, as I have already mentioned, I dump crankcase air into the atmosphere so it is irrelevant to engine perf. The gain is in that you can create a low compression engine without stripping the motor down. I'd very much like to see your 20Hp gains from running a vacuum in the crankcase.


Joey, I really can't say for sure how much the compression will drop with glowplug swap...I haven't had a good chance to try it on mine yet, I need a failsafe startup system and a spare set of glowplugs on hand before I can try it. I would say the only way to really answer that is you'd have to do it to a loose head and measure the change in volume by fluid displacement.

We can't prove anything here. It's only theoretical and experience. Well, maybe real dyno numbers. But neither of us have those now.


Technically you are not dumping crankcase air into atmosphere, you are pushing it. If we are talking about Slight increases in power, then yes it is relevant to engine performance. Slight I said.


Your goal was to remove the GP's, lower CR, and increase boost. As you said, more blow-by. Me says more power to push out of crankcase.


Typical gains on the vacuum pump have been seen in Gasoline powered 500 cubic inch race engines. I've done it. I've seen 25-30 on 600 and bigger engines. I'm not sure what it would do to our Turbo Diesels, but the theory is it would make power.


Vacuum in the crankcase 'Frees' up the rotating assembly, making it easier to turn.


Here, read this http://www.dragstuff.com/techarticles/vacuum-pumps.html.


I have no affiliation to these guys or anybody in the article. I just found it on a quick search. I don't even use there pumps on my motors.

I could imagine that a partial vacuum in a crankcase of an engine that is rotation at 6000+ RPM you might see a slight gain, were not building gasoline dragsters here. We're talking about diesels that run half that speed, and I can assure you, pressure on the crankcase with dual breathers at full load full RPM is less than 1lb and completely irrelevant. Even still your input and references are duely noted and appreciated, but I think I'll pass.


In addition to that, vacuum levels they refer to would not be possible on these engines without rebuilding the engines and replacing all the seals because they're not designed to hold any vacuum and will draw air/dirt into the crankcase.Edited by: Texas Diesel Guy

BOYS, BOYS


We are starting to sound like another page out there. I guess this is like the TV switch. If you don't like what the guy is posting go to the next item.


From my seat I believe if the hatfields and mccoys here would get together for common good, WOW what would we have there. I have not seen many Injection Pump Experts willing to share what they know, and combine that with the other experience's here. There could be a great deal of infomation together.


The SUM of the whole is greater then the sum of the parts.


Whatcha think

Back to the topic at hand with the glow plugs . . .


I know that there are some really great intellegent people here, some with a few letters behind their names. . .http://www.dieselplace.com/forum/smileys/Geek.gif . .. anywho, isn't there some algebraic equation that you can use to start off with beginning compression factor, and volume of the glow plug that it displaces, and then figure backward to see what the final compression ratio would be? All this to save a complete teardown and rebuild with fluid displacement.

I'm sure there is a formula....does anyone know bore/stroke offhand? I'm going to try and look it up...


found it...4.06 x 3.82" and I see posted 21.5 and 21.3 for compression ratios.


let me do some paper math real quick....Edited by: Texas Diesel Guy

OK here we go substituting 3.14 for pi heres my equation...


pi *radius squared* height = volume displacement in cubic inches


3.14 * 2.03 * 2.03 * 3.82 = ~49.432


displacement / compression ratio = volume above piston TDC


49.342 / 21.5 = ~2.29


add estimated volume of glowplug tip I just estimated that to be .08, add that to the TDC volume for 2.37 divide that back into the displacement volume gives you a compression ratio of 20.8:1.


somebody confirm this for me please while I check my math....

Here's a few fig's for ya:


Clyinder displacement: 49.45 ci. x 8 clyinders = 395.63 ci.


Okay, now the bore and stroke give us the displacement of the engine, but isn't there a prechamber that has to be accounted for? I not that hip on how all this works, just throwing some stuff out there. So, how do you figure backwards from compression ratio with displacement to figure the increase in volume of that pre-chamber? and then the $64,000 question:


When you remove the glow plugs, what you will actually gain? How much more O2 is displaced at 21.3 CR in that volume taken up by those plugs? If I understand this correctly, you will drop your compression ratio, add more oxygen for combustion, and increase the amount of fuel that the engine can use by removing the glows.


Just hope for a warm winter.http://www.dieselplace.com/forum/smileys/Big Smile.gif


EDIT: You posted while I was figuring. This is one for the dyno if it could be checked out looks like. Does anyone know how much the HP rating changed on these engines when the CR was modified? Maybe we could interpolate (sp?) those numbers to see what paper says. Real life gonna be best test. All this to maybe net out an extra 1.224 horsepower? I was just guessing that number, but I wonder what the number will actually be.


Thoughts anyone?


Edited by: knkreb

ok guys, here it is. compression information from the true definitions of static (non boost) compression using classical thermodynamics and internal combustion engine definitions. it deals solely with volume and has nothing to do with pressure or heat. the true diesel stroke is assumed as an issentropic process. those are the assumptions made in evaluating true theoretical compression ratio. so dont slam me if your pressure related guages say otherwise. this is the correct theoretical way to calculate static compression ratio.


Cr= compression ratio


Vtdc= volume @ top dead center


Vbdc= volume @bottom dead center


Vd= displacement of the motor


Vd= 395 cu in/8cyl=49.375 cu in / cyl=Vbdc


CR of 6.5 td = 21.5= Vbdc/Vtdc=49.375 cu in/ Vtdc


Vtdc = 2.297 cu in


these numbers can now be used as constants.


now remove the glow plug and determine the volume of the glowplug in the combustion chamber using liquid displacement or a CAD model. if you remove this portion from the combustion chamber, you can add it to both the Vtdc and Vbdc and refigure your Cr. this will give you a true measure of your static compression ratio.


new Cr =(Vbdc (49.375) + Vglowplug)/


(Vtdc (2.297) + Vglowplug)


hope that helps

...umm yeah, isnt that exactly what I said? the only shortcut to calculate displacement of a single cylinder which may or may not be more accurate is to simply divide 396 cid / 8 cyls = 49ci / cyl. 49/21.5 = ~2.279 + .08(glowplug) = 2.359 x 1/49 = 20.77 new CR.Edited by: Texas Diesel Guy

glowplugs have metric threads

all the more reason to simply knock the tips off them.

glowplugs have metric threads











And they are not tapered like pipe plugs. They seat like a spark plug with a tapered seat. Dunno how a 1/8" NPT worked for a gauge...

I missed where someone cc'd the head chamber, head gasket volume, measured compression height, piston volume, and prechamber volume. All necessary to calculate CR...


Fill in the blanks:






Bore
Stroke
Swept Volume


Piston Volume


Head Gasket
Pre Comb. Chamber
Deck Vol.
Valve Recess


Total Volume





I've named some of these things a little different, but SSDD...






Edited by: Kennedy

OK... this is really much simpler than it may sound...we already have all the known values and ratios we need to make our calculations.


396 total cid = 49ci's displacement per cylinder = area of piston x stroke.


since 21.5:1 is the known stock compression ratio, then the volume above the piston @ TDC = 1/21.5 of 49 = ~2.279


I really don't have a good figure for the volume of the glowplug tip (if anyone has one handy for measurements that would help http://www.dieselplace.com/forum/smileys/Big Smile.gif) but my best guestimation yields .08


now all we have to do is add the new volume...2.279+.08=2.359 and divide cylinder displacement by this to get new CR...49/2.359= ~20.77.Edited by: Texas Diesel Guy

BOYS, BOYS


We are starting to sound like another page out there. I guess this is like the TV switch. If you don't like what the guy is posting go to the next item.


From my seat I believe if the hatfields and mccoys here would get together for common good, WOW what would we have there. I have not seen many Injection Pump Experts willing to share what they know, and combine that with the other experience's here. There could be a great deal of infomation together.


The SUM of the whole is greater then the sum of the parts.


Whatcha think





I've never seen, or heard, anything like this thread on the Diesel Page. I don't read the idiot on the Yahoo site, so don't know about that one.

you have to add the glowplug volume to the total cylinder volume however negligible the small amount may be to get the correct Cr. check out my last post about Cr. everything needed to calculate it is there except glowplug volume.

displacement is unchanged by changes in volume of the head, bore and stroke remains the same. Everything you need I have already written twice now.

Sorry, but you're both wrong.


If X denotes the combustion chamber volume, CR denotes the compression ratio and VS denotes the swept volume, the relationship is (X + VS) / X = CR. This can be solved for X. The result is X = VS / (CR-1). Using 395 CI (round number) as the basis, each cylinder has 49.375 ci displacement or swept volume. Using 21.5 (if that's really it) as the compression ratio, we get a combustion chamber volume (including precombustion chamber) of 2.408 ci.


Rounding errors will likely affect this number significantly. Both of you set up the initial problem incorrectly.Edited by: ronniejoe

Next thing you know you guys will be trying to put extra washers under your injectors to reduce the compression ratio. Let's see now/ Hmmmm, maybe I could get some of those no foul adapters like they use on sparkplugs and adapt them to an injector and put an air pump on the engine and route air to the adapter thru some hoses to pump more air into the cylinder. Hmmmm? And then route it to some check valves and use it as a sand blaster air compressor.

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

http://www.dieselplace.com/forum/smileys/Clap.gifhttp://www.dieselplace.com/forum/smileys/HiHi.gif

ok, i guess after a BS in mechanical engineering and course specific to the internal combustion engine im wrong. if yall would like me to send you the pages of the text that my info came from let me know

Yep, you're wrong.


I, too, have a BS in mechanical engineering, so let's just not get too fiesty.


If you pause and think about it, you will see your mistake. The piston sweeps the volume from top dead center to bottom dead center, which is the 49.375 ci. The combustion chamber volume is still there above that swept volume. You have to add the combustion chamber volume to this number to get the ratio right. The volume above the piston at BDC is the swept volume plus the volume above the piston at TDC! That space didn't go away.Edited by: ronniejoe

Next thing you know you guys will be trying to put extra washers under your injectors to reduce the compression ratio. Let's see now/ Hmmmm, maybe I could get some of those no foul adapters like they use on sparkplugs and adapt them to an injector and put an air pump on the engine and route air to the adapter thru some hoses to pump more air into the cylinder. Hmmmm? And then route it to some check valves and use it as a sand blaster air compressor.





I'm waiting for someone to get out the plasma cutter and ventilate the hood or fenders...http://www.dieselplace.com/forum/smileys/Ermm.gif





Still waiting to hear the outcome of trying to start an IDI diesel w/o plugs...

BOYS, BOYS


We are starting to sound like another page out there. I guess this is like the TV switch. If you don't like what the guy is posting go to the next item.


From my seat I believe if the hatfields and mccoys here would get together for common good, WOW what would we have there. I have not seen many Injection Pump Experts willing to share what they know, and combine that with the other experience's here. There could be a great deal of infomation together.


The SUM of the whole is greater then the sum of the parts.


Whatcha think





I've never seen, or heard, anything like this thread on the Diesel Page. I don't read the idiot on the Yahoo site, so don't know about that one.





Yeap I know kind of deep thinking for that other page huh?

No big deal on glowless starting the 6.5L down here, JK, even in winter. What we call winter......


Ether can help, if necessary, if you absolutely know there is no glow to ignite the ether in the intake system as the intake valve opens.


WD-40 can help, as can a hair dryer.


Neither is needed here on the Gulf Coast.


However, as most folks know, there is absolutely no point in reducing CR by a half point or so.


Reduce CR to 18:1 (keep your glow plugs, folks), and Boost can be increased by at least 50%, while maintaining identical cylinder pressure as 21.5 on 7.5psi Boost.


More oxygen, more fuel, more power


Also gives capability to run Boost up to 20psi everyday, play or load.


Reduce piston crown height by 0.0625", iirc, results in one point drop.Edited by: gmctd

youre right, my bad

How about "destroking" the the crank? Less cubic inches & less comp/ratio.

That would also decrease displacement, less air flow, less power, staying within same rpm limitations in this engine.


3/16" shorter stroke, less torque.


Five oddly staggered head bolts per cylinder, to clear injectors and glowplugs, would not allow higher Boosts to regain that power, as in Cummins 359" six @30-45psi, and higher.


Iirc, Cummins stroke is over 4", maybe 4.5" - excellent for torque.


18:1 pistons are available, at identical weights as 21.5 stockers, permitting drop-in installation without pulling crank for rebalance, without reducing 396cuin displacement. Always best to have entire reciprocating assy balanced, tho, with flexplate and balancer.


Wouldn't hurt to have the crank nitrided and repolished, with matched bearings, while into it. Iirc, JK did that with his motor.

I may not have a BS in BS but I know math and geometry and nothing else is important to these calculations.


Bore and stroke determines displacement, and nothing else, that remains constant. This constant displacement divided by volume at TDC is your CR.


VS / X = CR.


since VS and CR are know, we flip the equation to solve for X...


multiply both sides of the equation by X... VS (X/X=1) = X * CR.


divide both sides by CR.... VS / CR = X


49/21.5 = ~2.279


now we have a known value for X we are going to increase X by removing the glowplug making X = 2.359.


now we refigure our original equation using X and VS as our knowns to solve for CR.


VS / X = CR. ~49/2.359 = 20.77

TDG,


Your BS is getting deep. I explained where you were wrong, yet you refuse to accept it.


The swept volume (VS in your example) doesn't include the volume of the combustion chamber. It's really pretty simple. That volume is there when the piston is at TDC... it's also there when it is at BDC.


BTW, no BS required. Simply High School Algebra and simple observation.


The volume of the combustion chamber is:


X = VS / (CR - 1)


End of discussion.

OK OK OK, your right, I stand down, I see what you mean, my apologies... obviously your BS beats my BS. http://www.dieselplace.com/forum/smileys/Confused.gif


not as simple a calculation as I thought...allow me to correct myself...


49.5cid is displacement per cylinder (396/8) = VS


VS * (CR+1) / CR = BDC vol


49.5 * 21.5 / 20.5 = ~51.915


BDC - VS = TDC vol


51.915 - 49.5 = 2.415


now we add the volume of a glowplug to BDC and TDC and recal...


New BDC / New TDC = New CR


51.995 / 2.495 = ~20.84


atleast I was close before http://www.dieselplace.com/forum/smileys/Wink.gif, and yeah, its a pretty modest change in CR. enough to be noticeable? not really sure, I'll leave that to the real BS experts out there!Edited by: Texas Diesel Guy

Gee, and my arguement in math class always was: "where are you gonna use this stuff anyway?".http://www.dieselplace.com/forum/smileys/Embarrased.gif


So, if I borrow a few numbers from a few peoples posts. That if the compression ratio changes about .73:1 total change, (which I know you all are still debating who's numbers are right, but lets just try this out here. . .)


If by interpolating a few other numbers such as changing the compression ratio down to 18:1 from 21.5, you could possibly run 50% higher boost. Taking those numbers *assuming* you can do this, you could *possibly* see a 14% increase in fuel/air intake into cylinder (thus translating to: *possibly* 14% more horsepower per point change in compression ratio) follow my numbers anyone?


So, if you removing the glows from the displacement of the engine, could you net out about 10% extra out of it **or** is that just on paper? *IF* that is true, you could be adding to a 195hp engine 19.5hp? Plus the benefit of improved atomization.


How ever you arrive at whatever math, is whatever you arrive at on PAPER. How will it fair on the dyno, and most importantly, will the stinker start for ya when you want to go in the winter? What good is an extra 10% out of a truck that mightin' not start? Getter' to start, and log what she does scientifically, I'm anxious to see.


TDG, I think it's got some merit, but it's gonna be where rubber meets the road is where it's gonna count.

Although i haven't seen the combustion chamber of the 6.5L yet (sure it's just a matter of time before i rip the heads off).. lowering hte CR a few points is gonna be neither here nor there.

now i'm no diesel expert.. but i do know my way around gas engines pretty well.

The only thing lowering the compression will get you is the ability to not tune to a knife edge.. ie there is more margin for error in tuning.

more squish.. bigger bang..

diesels have the unique ability to inject the fuel when it's needed, and not before combustion occurs.

and yes you can pack more oxygen into the cylinder before EGT's start climbing when you lower compression, but you are also losing volumetric efficiency in the process. one reason that people who really know what they are doin are getting paid the big bucks..

i'd be more interested in how to increase the volumetric efficiency so that the air charge can be maximized during valve events. with that said.. anyone got some good pics of a head, combustion chamber and intake/exhaust ports?

considering how choked the intake is.. i'm sure there's lots of room to improve efficiency without losing the benefits of high compression.

the glow plugs are a completely different issue. i would imagine that getting rid of them, and still being able to start in -40 weather would be a good thing.

-- WheatKing

Note: I'm not commenting on whether this will be good or bad. I'm just correcting the calculation that is being made.

We have the same struggle in the refrigeration trade. With piston compressors, what's left over in the top of the cylinder will re-expand on the down stroke. Thereby reducing the capacity of the compressor. Difference in a refrigeration compressor and engine is the compressor has reed valves that open by pressure, whereas the engine is predetermined opening and closing of the valves.


With that volumetric efficiency in mind, if you have x-amount of exhaust gas left in the top of the clyinder that will not escape during the upstroke. Leaving the opportunity for more products for combustion to be hangin' out for the next intake stroke. Kinda like an unwanted EGR.


I read an old diesel book a few months back, that outlined how, I think it was the 8V72 diesel, don't quote me on that. If I understood it's method of operation correctly, it had a blower on it that pushed fresh air through the cylinder the give it the fresh air charge and to help push out the products of combustion.


I was just thinkin' maybe if you could change the valve opening events, you could "blow" the cylinder clean with fresh air, but alas, your intake manifold would have to have a higher pressure than your exhaust manifold. If I understand the operation of the tubro correctly, I don't think that it's possible.


Even after all of that, I'm wondering what amount of loss there would be in that volumetric efficiency reduction? Anyone have any algebra on that one?http://www.dieselplace.com/forum/smileys/Geek.gif

I'd pay 5 bucks to watch a gasoline-fueled engine run with 21.5:1 compression ratio, if price of admission included the field glasses I'd need to see at the distance required for personal safety.


You'd need to include flying objects with those knife edges...........http://www.dieselplace.com/forum/smileys/Ermm.gif


With the direct-injected Diesel combustion chamber in the piston, valves are not shrouded, giving the naturally-aspirated Diesel VE levels only dreamed of by gasser dudes.


Diesel intake is open - no throttle plate or venturi to reduce VE.


Diesels designed for turbo-charging use exh-int duration overlap so fresh pressurized charge blows out residual combusted charge.


Turbo-charging increases VE to levels un-imagined by gasser dudes.


At all rpm ranges.


The separate Ricardo Comet V pre-comp chamber, nestled snugly in the head, promotes swirl necessary to mix fuel charge with oxygen charge, so each tiny droplet of fuel is completely enclosed in oxygen, ensuring total combustion and max btu from that tiny droplet.


And, all it's companions.


The position of the glow plug, necessary for cold-starting an indirect-injected Diesel, naturally assists in that swirling mixup.


The pre-comp chamber, retaining most of the heat produced during combustion, ensures complete fuel burn at cold-start, ensuring excellent drive-away - satisfying customer 'drive-ability' requirement.


Draw-back is, that pre-comp chamber also results in reduced ability for engine coolant to remove that heat.


Second draw-back is, piston has less combustion area in the crown, which prevents adequate exh-int valve overlap, necessary for blowing chamber clear of preceeding combustion left-overs.


Even at that, the 6.2L\6.5L series is noted for excellent fuel mileage, with even the big Subs attaining 27mpg.


Volumetric efficiency understated, I would think.....Edited by: gmctd

If you want to see a gas engine run with 21.5:1 CR, just take a 6.5, remove the injection pump, and add a throttle body and fuel injection. Just wear safety goggles!


Highest I've seen a gas engine run on pump gas is 13:1 on a Jag V12, but it can only get away with that because of the very oddly designed combustion chambers, and the restrictive exhaust port which limits overall flow significantly.

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

I beleive the reason this post was started was the concept of gaining better combustion. the point of removing the glowplug would be to gain a better fuel atomization in the chamber which it should theoretically do. it also lowers Cr without a doubt, but whether that small amount is worth anything is arguable. boost and wastegate levels would have to be tweaked to gain much out of altering Cr. I do agree with the statement about better fuel dispersion, but i dont know that lowering Cr such a small amount will help too much. but i wouldnt want to start my diesel without a glow system

No big deal on glowless starting the 6.5L down here, JK, even in winter. What we call winter......


Ether can help, if necessary, if you absolutely know there is no glow to ignite the ether in the intake system as the intake valve opens.


WD-40 can help, as can a hair dryer.


Neither is needed here on the Gulf Coast.


However, as most folks know, there is absolutely no point in reducing CR by a half point or so.


Reduce CR to 18:1 (keep your glow plugs, folks), and Boost can be increased by at least 50%, while maintaining identical cylinder pressure as 21.5 on 7.5psi Boost.


More oxygen, more fuel, more power


Also gives capability to run Boost up to 20psi everyday, play or load.


Reduce piston crown height by 0.0625", iirc, results in one point drop.








My 6.5 resides in TX (Temple-ish) and from what I am told, it needs just a bit more glow than stock down there as well to light off.





The BD reflash starts like absolute crap with stock glow duration.





I don't think today's WD-40 works does it? Word was it had propane as a propellant years back...

Yep - that's East Texas Piney Woods area - tends to get that strange white stuff all over during Winter.


Considerably cooler there, than here.


Btw, if you're coming to Texas to visit the truck, you'll need to bring your own chrome dual breather set-up with you, from there.


Seems as tho there's been a 'run' on them, recently, and all the parts houses here are back-ordered, to a couple states over on each side.


They do have the black-on-black 275hp versions, but the ladies are not as impressed - that chrome seems to do it for them.


You should also be aware, the GM Diesel trucks have replaced the Honda Civic R's at the top of the thieves' hit list, which is a sad thing, as they rip open the hood, looking for the dual Chrome breather set-up - if the truck does not have the goods, they just leave it, with the hood shredded and peeled back, like a tin of sardines.


It's an insurance nightmare.


Edited by: gmctd

Kennedy, I definitely agree with you there, the stuff they put in WD-40 cans these days just ain't what it used to be.


This mod is most definitely about the 'little here little there' approach to improve performance. I really think it will be a noticeable gain, infact I think I'll do that first and run it around for a bit to see if it makes any difference on its own. Lowering the compression in itself should make more power because it takes less energy to push the piston up on compression everytime it makes the trip, and it should be able to make just as much power on the way down, more if the spray pattern is improved. I'm hoping I can hear a difference at idle even, but we'll see ;)


Wheatking, As far as benefits of high compression....I'm not so sure the 6.5 is the engine to make your case on, my experience 6.5s are the biggest complainers about cold starting and worst to burn out glowplugs, not to mention crack heads.

Yep - that's East Texas Piney Woods area - tends to get that strange white stuff all over during Winter.


Considerably cooler there, than here.


Btw, if you're coming to Texas to visit the truck, you'll need to bring your own chrome dual breather set-up with you, from there.


Seems as tho there's been a 'run' on them, recently, and all the parts houses here are back-ordered, to a couple states over on each side.


They do have the black-on-black 275hp versions, but the ladies are not as impressed - that chrome seems to do it for them.


You should also be aware, the GM Diesel trucks have replaced the Honda Civic R's at the top of the thieves' hit list, which is a sad thing, as they rip open the hood, looking for the dual Chrome breather set-up - if the truck does not have the goods, they just leave it, with the hood shredded and peeled back, like a tin of sardines.


It's an insurance nightmare.











http://www.dieselplace.com/forum/smileys/Approve.gif gmctd You ain't right bro.

yeah, I should never have put those pictures of mine on here, gotta go buy an alarm system now.

So, just thinking


The 6.5 heads are crack prone, have small valves and use glow plugs.


Recasting the heads could solve that.


Has anyone ever thought to lower the compression by increasing the chamber size? make enough room for bigger valves?

thought about it, hell yeah, Direct Injection, 32valves, but who would you ever get to cast a pair? Valvetrain would pose a problem for 32valves, but there's got to be a way to make it work.

The spirit of my Viking forefathers calls me to do it for myself. Molten iron and ice water run through my veins.


Actually, I was thinking 16 bigger valves, but I'm open to change.

Ronnijoe I was wondering why you always have somthing negitive to post when TDG post somthing. He is just trying to ad to the forum. He seems like he knows his stuff. Give him some slack.

Common sense and reason. That's all.


Well,... Throw in 25 years of engine building experience, documented performance improvements for the 6.5 and 15 years of engineering experience. His initial claims for the "dual breathers" more than implied that I, and lots of others, had wasted our time and money on intercoolers. I promptly explained that he did not understand where the real source of heat in the intake came from. He promptly implied that I knew nothing.


Hey, you believe him? Great. Do everything he says, then hook on to a 10,000 lb. travel trailer and come run with me. I'll wait for you after I've put about 50 miles between me and you. If you don't show before too long, I'll come back and help you remove your overheated vehicle from the road way.


I've towed close to 100,000 miles with a 6.5. It has taken a lot of work and some investment to make it work like it should. Not some gimmicky, half baked "mod". It now tows with the best of them. As Billman said, someone might be gullible enough to buy the line.


I waited a while before correcting the calculation errors on this thread. I waited to see if he would fix it himself. When I corrected it, he implied that I was full of BS. Well... Judge for yourself.Edited by: ronniejoe

Displacement of the glowplug can be measured in a graduated cylinder with the plug immersed to the point that the plug goes into the prechamber.


RJ,


Don't forget that the experience of time and creation is ours if we can only re-member it.

Common sense and reason. That's all.


Well,... Throw in 25 years of engine building experience, documented performance improvements for the 6.5 and 15 years of engineering experience. His initial claims for the "dual breathers" more than implied that I, and lots of others, had wasted our time and money on intercoolers. I promptly explained that he did not understand where the real source of heat in the intake came from. He promptly implied that I knew nothing.


Hey, you believe him? Great. Do everything he says, then hook on to a 10,000 lb. travel trailer and come run with me. I'll wait for you after I've put about 50 miles between me and you. If you don't show before too long, I'll come back and help you remove your overheated vehicle from the road way.


I've towed close to 100,000 miles with a 6.5. It has taken a lot of work and some investment to make it work like it should. Not some gimmicky, half baked "mod". It now tows with the best of them. As Billman said, someone might be gullible enough to buy the line.


I waited a while before correcting the calculation errors on this thread. I waited to see if he would fix it himself. When I corrected it, he implied that I was full of BS. Well... Judge for yourself.





NOW RJ noone here is questioning what you have done BUT some of us like to see what else other can come up with when left to think outside of the box. If we all stopped looking for the what if's then I gyess we sould all get in line and everyone by he same stuff for our trucks. Once again if different thinking about this engine had not taking place by someone then you nor anyone else wold be where you are at now with you truck, right.

Doing 32 valves would be complicated, but it could be done. After all, Isuzu did it when they built the Duramax. It would require a complicated arrangement of rockers is all, but it would also allow for much more flow. 16 larger valves would be more practical, but if you're going to the trouble of doing the casting yourself, might as well go all-out. QM, I'll gladly help in whatever ways possible in the design/fabrication of these new heads (although how useful I would be is another matter entirely as my knowledge of diesels is still very limited). Bet if they were designed properly a lot of off-the-shelf parts could be used, lowering cost. Something you could do if designing them yourself.

I know someone who actually CC'd a head (inluding precomb chamber with glow plug, piston, etc.


Personally, I believe the glow plug removalis barking up the wrong tree. We need to creat the volume in the main chamber, not the pre chamber.

I'm all for any help I can get. Since you guys like setting up algebraic equations can you show me how to arrive at what increase in volume per cc will give me 19:1 overall and what total displacement this would be?


Todd,


Perhaps you could use two stock intake valves and two stock exhaust valves. Set them up to lift as pairs.

RJ, thats not really right to say is it? I never said or implied that you were wrong (did I? if I did I apologize, I do frequent this site beer in hand quite often), intercoolers are undoubtedly the best way to cool hot IATs, hands down. I was merely suggesting the breather setup as an alternative approach to cooling intake, and allowing more power to be produced with stock boost levels. No doubt its not the magic bullet (or bullets), but the chrome does look nice http://www.dieselplace.com/forum/smileys/Thumbs Up.gif, I mean what else does Edelbrock sell that will fit anywhere on a 6.5?


I didn't get a chance to do any of the work I was planning on the truck this weekend, I had to pay the man, and my injector guy bailed on me too...but I did build some DS pumps today, but none of them for my truck http://www.dieselplace.com/forum/smileys/Disapprove.gif. So, I'm hoping I can do it next weekend...


Kennedy's right, putting more air, and thus fire between the piston and the head would be best...until I win the lottery, I'm afraid the motor is going to have to stay pretty close to stock, afterall us pump guys don't make that much money.Edited by: Texas Diesel Guy

QM: Pair of stock intake/exhaust valves would most likely be too much and wouldn't fit in the bore. With 4-valve/cylinder motors you always have 4 smaller valves that will then take up a larger overall percentage of the area. So, I'd have to do a few calculations and work from there.


Also, there are programs/spreadsheets out there where you can input all the parameters (bore, stroke, piston dish/dome, head gasket thickness, combustion chamber volume, distance piston rests at TDC from deck height) and it will tell you the compression ratio. Pretty sure you could find it on Google in under a minute.

should be able to calculate how much metal will have to be removed just from what we know already... Let X equal volume to be remove from either top of piston or underside of head...


(51.915 + X) / (2.415 + X) = 19


removing 0.35 ci would give you 18.964

is that 0.35 ci per CC and 2.80 ci over all 8? Would that make total displacement 399?

displacement does not change, bore and stroke will still be the same no matter what you do to the pistons or heads.


But yes, thats .35 ci per cylinder to make 19:1.

Seems like such a tiny change, but if you can open the valving in the process it should be worth it. Theoretically how much more boost will be able to enter the cc? the 18:1 claims 50% increase possible.


I'm glad the displacement doesn't change. I have been attracted to the 396 since before owning one. Magic numbers to me.Edited by: quantum mechanic

I looked at dished valves, thicker head gaskets, and shortening the compression height on the pistons via either rod length changes, or shorter crowns.





In the end, I cut the piston with a dish. I feel it is best to bring the piston above the deck to keep the fire up above the bottom of the head gasket, and off of the cylinder walls...

What if you had a machine shop mill out a tiny 'bridge' if you will to join the prechamber to the valves and top of piston area. If you could have them remove precisely the .35ci then you could have a much improved prechamber and the dropped compression at the same time and never touch the block.


http://www.dieselplace.com/forum/uploads/B78_head4.JPG

I like that as a right now solution. I would still want to up the heads to BB calibur but as long as there isn't anything behind that area it's worth doing once for the experience. I have enough equipment to do it myself.

How many of you are proficient at computational fluid dynamics? How can you say that you would have a "much improved prechamber" by hogging an arbitrary divit in the head? The shape of the existing prechamber was most likely designed (using sophisticated analytical tools that you don't have) to provide good swirl, flow characteristics and combustion properties with the glow plug installed! I think you're barking up the wrong tree.


Granted, trial and error can get you there eventually, but you need to at least have some idea what the theory is before you start hacking.http://www.dieselplace.com/forum/smileys/Confused.gif

RJ,


The thing you have to remember is GM used the same computational fluid dynamics that brought you this monstrosity:


http://www.dieselplace.com/forum/uploads/C52_downpipes.jpg


I would cut a channel out of the prechamber and widen it taper it out as it approached the valves.


I didn't have to study fluid dynamics to understand flow. I don't just go with the flow, I create it.





Edited by: quantum mechanic

If the 6.5 engine is known for anything, its not the miracle engineering inside, its the fact that its the cheapest diesel to build, which is why the military buys them for Humvees, lowest bidder. The 21.5 compression ratio was copied from the Germans because GM didn't know better, the prechamber was used because its cheaper to make heads/injectors for than D.I.

Looking at the picture of the tiny prechamber port opening in th CC makes me want to call the local junkyard for a quote on some 6.5 heads to have a pair to work on. It's amazing to me with what's known about this engine that it hasn't been tried before.

I'm sorry. I'm in the presence of genius. I am truly humbled. I didn't realize that you actually create flow.http://www.dieselplace.com/forum/smileys/Disapprove.gif


Sometimes the accountants and less than capable manufacturing engineers get in the way of a good design.

Genius is submission to your higherself (GOD). I create my own flow, positive or negative, in all I say and do. Everyone does the same.


Life is a vibrational energy reality, what wave are you riding?Edited by: quantum mechanic

Ronniejoe do you have a good thing to say about any post? Our do i just not get your humor? And Im not trying to pick any kind of fight out of you. Im just wondering.

RJ, your right, Diesel is a Science, not a Sense. There is a great deal of mathematical method, physics and engineering involved in designing producing any engine. Obviously, they did have a clue what they were doing as this engine started production in '81 and they're still making them today. But thats just it, when Detroit's engineers sat down to design the 6.2 that would later become the 6.5, they weren't thinking about how many HP they could make, they were concentrating on how they could make an engine that was reliable, inexpensive, and could provide years or decades of service in multiples of applications. Mass production has its benefits, but it has its detractors too. Obviously, the IDI/Glowplug setup was what they determined to be the most reliable and startable in the most climates, and they were probably right, I wouldn't swap in 18:1 pistons and take out the glowplugs and move to Pikes peak and expect it to start...ever! These engines were made to be versatile, and what we, all of us, yourself included, are trying to tailor these vehicles to meet our own needs. Admittadly, we could definitely be losing some of the versatility, but its a trade-off...increase boost, drop compression, increase fuel delivery so now you can't move to Alaska, but you can tow your trailer across the lower 48, and thats where your truck is going to spend its life. There is more science involved definitely, and the scientific approach is always more accurate than the 'try it and see' method, but if the approach is logical, and the method is reliable, and your willing to risk it, then it's worth a shot.

All science is based on sense. Perception with a methodology. What we experience through perception we "know".


And I have compiled a 6.5 diesel "sense". a feel for what is and what should be.


This forum gives voice to that knowledge. I want to hear from a guy who's experience has tought him something whether he's agreeing with me or condeming my idea.

Its very possible that the prechamber they designed 20 years ago may provide optimal swirl and startability characteristics for a 190Hp 21.5:1 engine. But were trying to build an 18-19:1 250+Hp engine. Kennedy and several other have also stated and I think everyone will agree, the more fire you can get over the center of the piston, the more power you can make, and we all know dropping compression allows you to run higher boost. So why not make a path for the fuel/fire to follow to get there? If I had the machining capabilities and the time, I'd do it next weekend.

I could always take the pair off my '93, if their unobtainable at the salvage, work them and swap them onto my 94.


I'll make a 1/3 of a cubic inch guage out of putty or something pliable that I can measure the channel with.

thats exactly what I was going to prescribe, then you could use the putty to match them all to the same dimensions.

Not a good example, QM - those pipes were designed by GM engineering, then "modified" on the production floor, under the rules of 'autonomous self-determination'.


We don't need no stinking prints......


May even be other considerations, but just as bad is speculating without being aware of all the data, or even that there is any other data.


Most folks with no training or background wonder if the speculator is on to something, while those with the training and background just wonder if he's on something.


Even those who attest to tremendous training and background on GM, Cummins, Ford, etc Diesels - read a few of their posted replys, and they can easily be pegged as 'got it', or 'claims it'.


Ronnijoe offers logical data, from a 'got it' background, where even I, a high school dropout, can see he is right.


If any can't quite peg me, I am a 'got some of it, furiously tryin' to get the rest of it' poster. Gives me an edge, because I know enough to recognize what to believe, and what to question as believable.


While I too am a Diesel owner\driver, I hand-built the Diesel truck which I drive, over a 5-month period, and which now has 40,000 miles accumulated since the total rework, four and a half years ago.


And, I'm still 'gettin' it'.....


Where you guys are speculating about having that trench cut is right where the weak point is in the heads, reason enough for GM to reduce the size of the exhaust valve in '83, after the streets ran green with anti-freeze coolant in '82.


That vague, out-of-focus ~2"dia circle at the bottom of the picture is the IDI pre-combustion chamber, called the 'pre-cup', of Ricardo Comet V design.


It is so efficient, that, with the Stanadyne DB2 inj pump, the 6.2\6.5 series gained reputation as 'the smokeless Diesel'.


It is also the source of the weakness attributed to those heads, as it is replaceable, meaning not part of the head casting.


Makes for really difficult heat transfer to the coolant in the water jacket, on the other side of the head casting from the pre-cup.


Required a special bore, in the water jacket between the valves above each cylinder, to get coolant to that problem area - it can be seen beneath each intake port, as a freeze-plugged opening.


Talk about your hot spots, it's crack city if subjected to repeated overheating, or overheating with major loss of coolant.


Don't need no more IDI heads, here, folks.


Were some rumors as to some direct injection heads for the 6.5, but none have surfaced, so it would take some enterprise to research, design, cast, and machine a reliable DI replacement.


One could probably do some research on the NavStar (Ford Powerstroke) 7.3 DI heads, which were derived from the 6.9 IDI heads, to get an idea of direction required.


One might also go to the Dodge forum, here, to view Hoot's pictures of the cut-away 5.9 Cummins, get some idea of 4-valves per cylinder driven off a single camshaft.


And the pistons with integral combustion chambers for Direct Injection.


And the size of the piston rod and crank journals required to handle that level of power increase.


And the size of the water passages to handle the increased BTU output.


And....well, maybe you get the required research picture necessary to re-vamp speculation into R&D.


And, about that trench - GM conveniently placed a specially shaped 'trench' right in the top of the piston, to channel the flame front, promoting efficient combustion.


Remember, this 400cin V8 Diesel was getting the same 27-28mpg as a 359cuin six cylinder, and in the heavier Suburban vehicle and some of the vans, to boot. Edited by: gmctd

the only DI 7.3s are powerstrokes with HEUI injectors, completely different system, no IP. The old mechanical 7.3s are IDI's as well.


I don't know, but one would think that if the Precup design has such a problem with heat transfer that it would help the problem by porting a passage to move some of the fire further towards the center of the piston.


Other than those two things I agree with you, 24v Dodge is exactly the setup I would try to model after. I still think the 'bridged' heads idea has a lot of wind in its sails, 16 valves should be sufficient with the added boost levels to move the air by them.

Have a cut away of a 6.5 head? It would be nice to see where exactly the water passages run.

Isn't the Cummins motor also an OHC instead of a pushrod type? Would give it an advantage in terms of placement.

Cam in the block, solid lifters - be easier if you'd surf on over and have a look - it's on this site.

RJ,


The thing you have to remember is GM used the same computational fluid dynamics that brought you this monstrosity:


http://www.dieselplace.com/forum/uploads/C52_downpipes.jpg


I would cut a channel out of the prechamber and widen it taper it out as it approached the valves.


I didn't have to study fluid dynamics to understand flow. I don't just go with the flow, I create it.











Me thinkith that part of the reason for the big scrunch in the down pipe is to speed the install on the line. If you can save a minute or two on the line that amounts to big bucks over hundreds of thousands of trucks.

Ok,


Assemby line modification, let me give you another example.


1. Unbalanced exhaust manifold. This is worse than the downpipe. The drivers side travels 3-4 times the distance the passengerside goes.


The only PhD I have is a post hole digger but I know the rule to making a better exhaust is improving balance and transition.


If you get under your truck and look at how the crossover ties into the turboside exhaust, you might notice the #8 and #6 exhaust ports are taking on the additional pressure where they come into the system. No wonder these clynders take all the heat and crack their heads.


2. Lack of intercooling. Turbos were all the rage in 1930 intercooling came right after, so why in 1994 didn't they use one.

I wonder if anyone has tried using the van head/manifold/turbo combination on a truck. Its got to be an improvement, turbo sits right in the center of the V, and they also use two seperate intake manifolds instead of one, and balanced exhaust manifolds. Surely you could even use the van downpipe since it curves behind the motor and over the same tranny used in the trucks. The intake would have to be replumbed, fuel filter and glow plug controller moved, but thats a small price to pay isnt it?

I've never seen the van. I'm still thinking about getting a pair of heads maybe I'll ask for 6.5 vans.

the only difference is the intake manifold bolts are vertical for the split manifolds, your best bet would probably be to find a wrecked van and steal the heads/manifolds/turbo off of it.

If I'm going to get that much i might as well get the whole block, it couldn't cost much more.

Gotta a visual picture in my head about what you want to do with the heads on this project, but isn't the head the weakest link in these trucks?

The heads are weak becuase they are subject to intense heat especially #6 and #8 cylinders without the 97 water pump/crossover, with the stock crossover pipe, exhaust manifold and lack of intercooling. The valves are a little small and so is the turbo/turndown.


A balanced exhaust should take the heat off #6 and #8, you can add the 97 cooling upgrades, an intercooler and I think it shouldn't be hard to convert where the turndown bolts up to a better flowing downpipe. with a reasonably priced pair of heads to work on, I'd like to see what can be improved (flow wise from the prechamber to the cc) without gouging it enough to stress crack it.


Might not be able to remove .35 cu in but I'll be able to widen the perchamber port and taper it in better.Edited by: quantum mechanic

the hummer also has a top mount turbo doesn't it?

yes they do, and theyre a PITA to get off.

How would you rate that exhaust/intake setup?

OK hear's my observations based on my motor:


1) the turbo options SUCKhttp://dieselplace.com/forum/smileys/Dead.gif. Someone somewhere has to have a better turbo. IMHO the turbo is the gorilla in this equation all other fiddling diddling is just that. Get a bigger turbo that spools up quicker but can still handle the top end and you'll have a SERIOUS HP gain. Example: my pump is bumped IIRC over 1/2 turn (5/8?), I get TONS of black smoke off the line and NONE at higher RPM right to redline. Without an intercooler. With a good turbo to eat some low RPM fuel I could add intercooler, crank the pump a bunch more and really have fun! The penninsular turbo IMO is better than stock one especially for towing, but I think there's still TONS of room for improvement. (as an example the penninsular turbo outlet has a smaller diameter than the intake manifold horn, so you need one of those 1 1/2" to 2" rubber tubes, which makes no sense...) I've heard 3rd or 4th hand someones cousins uncles grandmother put a cummins turbo on that went like a raped ape but not seen any numbers/documentation. I'd LOVE to stand corrected on this whole turbo area!!!


2) glow plugs SUCKhttp://dieselplace.com/forum/smileys/Dead.gif at 18:1. If you bump timing to maximize performance it eats glow plugs. The colder it gets the more glow time you need, really cold you'd have to start the glow cycle the night before.


3) did I mention I'm way happier with the motor now than ever before, just to be positive?http://dieselplace.com/forum/smileys/Big%20Smile.gif

On my '93, I'm wanting a non wastegated turbo that's for a 400 cu in to replace the GM-4. Any thing at a salvage yard like that? cummins, powerstroke?

I think a ½turn with the upgrades you've done is a bit on the conservative side, you've only added ~6-8mm of fuel, you could probably stand to give her another ½ turn or so, that will help spool your turbo faster, and possibly help your starting too.


Oh and for my rating on the van/hummer exhaust/intake setup, I would gladly swap it onto mine. I have actually driven a Hummer with one of my hot DS pumps on it, you wouldn't believe how close it was to spinning those 37" tires, that was one of the first ones I tried and it was the fastest 6.5 I had ever driven to that date, which started me on the upgrade path for my truck, I mean, I couldn't have a customer with a 6.5 Hummer that runs better than my 6.5 Blazer, that just wouldn't be right.Edited by: Texas Diesel Guy

more fuel=more smoke doesnt it? Then I'd be smokin out the entire city, not just the neighborhood, wouldnt I? Just the uninformed trying to learn...

You said the smoke clears once you get boost right? see if you can determine how many #s when it clears up, then turn the fuel up until it clears right around 20. Every 6.5 ever made will smoke until you get boost, no aineroid on the mechanical pumps to keep fuel down until you get boost, and no operation in the PCM to limit 'no-air' fuel either.

I think I've got it!? But, maybe not: let me see if I understand this correctly. You have trade off's in turbos. You have quick spool up time, or you get quanity of air. Which do you want? You can have it quickly spool up, or get the pounds of boost when you are towin'. Is this the correct observation or not?

Not really, both style turbos are capable of making plenty of boost, the larger exhaust housing is more of an older style turbo, non-wastegated just application matched to achieve desired boost. The smaller wastegated style has much less lag time but must be regulated to prevent overspooling and destroying itself or overboosting the engine. The '250 HP' turbo they sell is obviously aftermarket, and using whatever calculation method the used, they deteremined that that size turbo/housing would generate sufficienct boost on that engine @ 250Hp. The best answer I can give is that the smaller turbo would require too much shaft speed to generate the boost they wanted.

Need a replacement for glowplugs? Use a thermostart glowplug in the intake. Not only does it provide heat, it also injects additional fuel during cranking.

Diesel Pro, do you have any links/info on the thermostart glowplug thing? Im tired of glowplugs.

http://www.delphidieselsystems.com/diesel/pk/PKDDSproductitems4526.asp


Diesel Pro, is this what you are talking about? Does anyone sell an aftermarket version?Edited by: dslhead

Here is an image http://www.sphosting.com/dsl/fiatthermostart.html


Your local fuel injection shop should be able to order you one. They cost maybe around 100 bucks and will require some work to make it work. The threads are about 1/2" pipe. Will find out more correct info tomorrow.

G-9 glow's heated quickest, but burned out quickly under repeated glows.


G-11's were a little slower to glow, but much slower to burn out, being a dual element heater.


G-60's were a lot slower than the 11's, but would not burn out. Could take several re-glows to get lite-off.


Kennedy and others offer a quick-heat plug, heats like the '9s, still glowing brightly at the end of an 8-hour full-power test.


Similar pricing to the AC and Bosch lines.

The cheapest thermostart is around $24.00. p/n 1854050 Delphi. I don't know the volts or size on this unit. They offer 12 & 24 volt units with different fueling characteristics. They sell it by application. The best glowplugs are sold by Dephi.