Engine/Transmission (1998.5 - 2002) Burned up my engine today

[Gary - K7GLD]

Maybe a small discussion on physics of CR as opposed to atmospheric boost is in order - as I understand it, 2:1 CR is the same as reducing the physical space of the cylinder volume by 1/2, or twice as much air in half the physical space. 10:1 is 10 times the volume in the same space, etc. , so at a CR of 18:1, increasing the CR another . 5 or so would be considerably LESS increase in cylinder PSI than using turbo boost to add roughly 14 PSI, which would essentially DOUBLE the volume of air in the cylinders - what *I* am unsure of, is what that does to base CR in engines operating up near 19:1 compression ratios - maybe the engineers here have an answer...



Question is, if we DOUBLE the *volume* of incoming air going into a 19:1 CR engine with boost, what do we now have as an effective CR?



Or does the EFFECTIVE CR remain constant, and only cylinder PSI change - and what will change cylinder PSI most, a full point CR increase, or doubling atmospheric PSI?



That oughta keep the SAE geniuses busy for a moment or 2...

 

[ThrottleJockey]

At what point are you talking about? TDC or when the injection event occurs, or peak pressures?



And what about 190 psi in competition? Which has since been tuned down to a 'reliable 135 psi'!:--)





Brian

 

[Gary - K7GLD]

I suppose peak PSI would be most important that would seem to place the most stress on components... I've seen numbers for stock engines in the past - but long since forgotten them - they ARE impressive numbers!



Start increasing boost and other factors, and JEEEEEZE!

 

[Cliffman]

I know one thing, after all this work and money fixing and upgrading I'm gona put a redundant thermocouple on #6 and re-evaluate my 1350 limit!!!

 

[CFAR]

Increased fueling = Increased timing.

 

[WeirCummin]

Well Cliffman,

Seems your back luck has struck me. Towed the 5th wheel to the dealer for warranty work yesterday, about 100 miles each way. When we got back, I opened up the hood and low and behold, oil had blown out from the dipstick tube. Not to worried about it, since it still runs as good as always I checked the blowby plumbing, all was good. I then took it for alittle drive, seems that theres not a problem as long a I don't get the boost up. When I push on the go pedal and bring the pressure up it will blow oil. Pulled the injectors and took a look in the cylinders with the ol' bore scope, all looks good. Tomorrow I'll have to do a compression test to locate the cylinder(s) that are bad. I really don't want to pull the head, but it's the luck of the draw.

 

[Hohn]

Originally posted by Gary - KJ6Q

Maybe a small discussion on physics of CR as opposed to atmospheric boost is in order - as I understand it, 2:1 CR is the same as reducing the physical space of the cylinder volume by 1/2, or twice as much air in half the physical space. 10:1 is 10 times the volume in the same space, etc. , so at a CR of 18:1, increasing the CR another . 5 or so would be considerably LESS increase in cylinder PSI than using turbo boost to add roughly 14 PSI, which would essentially DOUBLE the volume of air in the cylinders - what *I* am unsure of, is what that does to base CR in engines operating up near 19:1 compression ratios - maybe the engineers here have an answer...



Question is, if we DOUBLE the *volume* of incoming air going into a 19:1 CR engine with boost, what do we now have as an effective CR?



Or does the EFFECTIVE CR remain constant, and only cylinder PSI change - and what will change cylinder PSI most, a full point CR increase, or doubling atmospheric PSI?



That oughta keep the SAE geniuses busy for a moment or 2...

Gary: The CR in an engine does not change as it is a mechanical feature built into the engine. At least when you are discussing static compression. So if you have a 17:1 engine, it will increase the pressure of the intake charge by at least 17 times. I say at least because the heating of the pistons causes an expansion of the air and actual pressure will be slightly higher. Notice the trend here-- there are MULTIPLE factors at work in any given situation.



Now DYNAMIC compression is a completely different animal. This CR accounts for the effect of intake intertia and delayed intake valve closure. For example, when you put in a big cam in a gasser, you need to raise static CR to maintain the same dynamic CR due to the later intake valve closure.



FYI-- ETh compression is 17:1 vs ETC compression of 16. 3:1 So 30psi of boost in an ETC is about the same as 28. 76psi of boost in an ETH. Thus, there is a difference, albeit slight.



To answer your question about doubling volume: since there is a linear relationship between pressure and volume (look at the units), when we double the pressure we half the volume (assuming the same mass). So if we DOUBLE the "volume" of air entering, we have necessarily doubled the pressure. It's worth noting that volume is a misleading term without pressure, since a gas will take the shape of its container. Mass flow is far more useful.



Let's revisit the issue of timing. Would NOW be a bad time for me to make my don't-stack-timing-and-fueling-boxes-with-injectors speech???



Seriously though, timing has a FAR greater impact than anything else on overall peak cylinder pressure. Just a few degrees too much advance can cause a doubling or even a tripling of peak pressures. After all, the peak pressure is what does the HG damage more than anything. The ETH is much more susceptible to really high peak cylinder pressures-- not because of its higher CR so much. Instead, it's the discharge curve of the pump-- a really short, spikey fuel injection event. This is the reason that ETHs respond so well to injectors. It's also the reason their HG are a little more fragile.



Ask yourself why the injectors on an ETh are SMALLER than on an ETC, even though the engine has had the power raised...



I do believe that timing boxes are generally safe on ETH engines even with injectors. But this is NOT the case if you tow very heavy. If the engine will see VERY heavy loads, what you want is LOWER compression and LESS timing while dialing in MORE boost. This gives you a high AVERAGE cylinder pressure to keep HP up, while also lowering the dangerous pressure spike at the moment of injection.



So does CR or boost play a more important role in determining cylinder pressure? Well, the answer is boost, because it varies from zero to whatever. The CR is fixed, so it ALWAYS multiplies cylinder pressure by that amount. The real variable is boost. But neither boost nor CR is as important as timing in determining peak cylinder pressure.



You have to be really careful when upping fueling with otherwise stock parts. You can either build a safe towing rig with less power, or build a hotrod. EGTs that are completely safe when running empty will soon melt something when towing.



By the way, you should REALLY explore the option of Swain Tech coatings for engine componentry. Check out their GoldCoat.



http://swaintech.com/race.html



Swain is THE leader in coating technology. I would use as much of their stuff as possible. Exhaust manifold, turbine housing, pistons, etc etc...



Justin

 

[Hohn]

Originally posted by CFAR

Increased fueling = Increased timing.

Yes and no. Increasing fueling alone has no effect on timing unless discussed along with HOW that fueling increase is achieved. Bigger injectors? Fuel box? Pulse width? Injection pressure?



Generally, a larger injector passes more fuel per unit time- duh. This tends to SHORTEN the time of the injection event, but it will not ADVANCE the timing, per se. The INITIATION of the injection event is still the same in both cases, thus the timing could be said to be the same. This shortening of the injection event tends to increase the peak cylinder pressure. Thus, less timing is NEEDED in the engine with larger injectors.



This is where we get to the different approach to building a tow truck vs. a race truck. Race truck= big injectors, high peak cylinder pressures.



Tow truck= smaller injectors, NO ADDITIONAL TIMING, and a longer pulse width.



Example:

1) sporty truck: Edge Comp, dd3s

2) TOW RIG: TST PMAX and dd1s or 275s



The tow rig needs to have less timing and smaller injectors to reduce peak cylinder pressures.



Justin

 

[Gary - K7GLD]

HMMMMmmm - may hafta re-think adding DDII's to my Comp for towing - at least as far as 5x5 is concerned...

 

[jrandol]

Originally posted by Gary - KJ6Q

HMMMMmmm - may hafta re-think adding DDII's to my Comp for towing - at least as far as 5x5 is concerned...

Nah..... no need to do that! Just slap on an extra turbo while your at it, Fire ring the sun of a gun and your good to go!!

 

[JRodgers]

Originally posted by ThrottleJockey



Iv'e just finished a rebuild on my 01 ETH. Lower compression race piston with a higher nickel and silicon content that are hard anodized. They will get hot but will not grow as much as a stock piston and will not score a cylinder wall. They were pricey, but I can wait another year for my PDR Twins. Did the Van Haisley thing with the 12 mm studs and the PDR 24v cam.

These pistons are also shaved and have the four valve pockets cut in them.

This is probably the most exotic 24 valve bottom end in Indiana. I would like to put on a new race version VP-44 and some J. R. Atkins HX-40 HT4B Hybrid twins, with some Mach 5s and dyno once!



That would be cool.



Brian

Dude, thats what I wanted to do, but I didnt quite get there. I am planning on doing the Mach 5 or 6 injectors though in the next few weeks.



Joe

 

[ThrottleJockey]

Joe

It gets pricey real quick, don't it?



Justin



Awesome post, thanks. Match these turbos to your examples for me.



Sporty truck- PDR HX-35 12cm2 with a wastegate?



Tow truck - B-1 or a PDR HX-40 with a 16cm2 exhaust housing?



Brian

 

[Big_Daddy_T]

I went looking for the math to compute peak cylinder pressures. Turns out you need a program to do it. Maps the position of the crank. Hmm.



Found this though. Pretty cool. http://www.bankspower.com/Tech_todaysdiesel.cfm They have some real nice drawerings.

 

[Hohn]

Originally posted by ThrottleJockey

Joe

It gets pricey real quick, don't it?



Justin



Awesome post, thanks. Match these turbos to your examples for me.



Sporty truck- PDR HX-35 12cm2 with a wastegate?



Tow truck - B-1 or a PDR HX-40 with a 16cm2 exhaust housing?



Brian

Well, others will disagree with me on my turbo recommendations, because it varies so much with the other stuff done to the truck (and with transmission type):



Sporty truck:KSB-1B, PDR 35/12WG



Tow truck: PDR35/16, PDR40/18, B1, etc. .



It's hard to point to specfics because there are so many OTHER variables. All I can say is this: in a tow rig you MUST sacrifice some spool up to gain PEAK EGT control. The sporty truck can have the tighter housing because it can afford to momentarily flash to 1400-1500 degrees and sometimes higher.



The tow rig is going to be faced with the worst case scenario-- SUSTAINED high EGTs. That means at LEAST a larger housing than the sporty truck, but probably a larger turbo in general. The tow rig must operate with a greater cushion of air across the board. That means less fueling and/or more air.



The stock Dodge ECM has a great feature in that it will retard timing under peak loads. It also adances timing under light loads and steady druise, just like a vacuum advance works on a gasser to take the timing from 14-15 degrees to as much as 60!



When you tow with an EZ, you lose the ability to retard the timing at high load. The EZ will not allow the ECM to back it off. This gives you great torque, but also VERY high peak cylinder pressures. That's why the engine will give you that "thump thump thump" when you tow hard with the EZ.



Now with small injectors, the spike in cylinder pressure is still safe. There's just not enough fuel to hurt something.



But when you combine timing on an ETH with injectors that are 100hp or more, all bets are off. Towing heavy with this setup is torture on the bearings, crank, pistons, and rods. Lots of shock-loading.



If you think about it, there's almost never a towing situation where you NEED more power than you could get from a PMAX and Mach 1. 5s or so. Odds are you are ridiculously overloaded if you can't pull it with that.



I can't stress enough how each truck needs to be bult with the END USE in mind, and that there is a very complex interaction between components that should be considered when planning your build.



justin

 

[Gary - K7GLD]

We all - or some at least - tend to get greedy with this HP stuff...



As many here know, I use my truck for towing a 5th wheel, and for play/experimentation. With the addition of the Comp alone, plus any slight advantage of the drilled airbox and K&N filter, I have all the power towing in the mountains a SANE person could ask - and enough to easily slip the clutch. I could probably top the Sierra at 100 MPH towing if the road was straight enough - and dern sure have NO problem on the grades maintaining 65 mph in OD with the cruise set... My egt sticks like glue at 1200 degrees under max load, boost at about 33 PSI max, and life is good. I *will* need a better clutch - and that causes me to then daydream of a bigger exhaust and DDII's - but in view of the above, and how well I can do with what I already HAVE, maybe I'd be smarter to simply leave well enough alone, other than perhaps a larger diameter exhaust if mine fails down the road...



That WOULD be the SANE thing to do...

 

[DLBurns]

Edge EZ

OK guys I am getting a little jumpy at the prospect of my EZ advancing the timeing far enough to melt a piston I saw Cliffs first hand today and it ain't pretty!!:--)

Should I consider ditching the EZ and going with mild injectors like EDM 2's?

I tow a 12K pound fifth wheel and don't really care to go up any grade faster than 60 MPH. The EZ allows me to pull most steep grades at around 50 MPH in 3rd gear.

I like the little extra umph... I get from the EZ, just don't want to toast my motor.

What are your suggestions??

Dave

 

[Cliffman]

Pics

Okay Men, this is not for the faint of heart. #ad




Dave, my suggestion is to get rid of the EZ and get the Comp and and DD3's. That way you can SHUT OFF THE COMP when pulling and just use the safe DD3's injectors. When pulling my 15K 5er up a 6% grade with the comp turned off and running on the DD3's my max EGT's are 1200. You just need some self-control and KEEP YOUR FINGER OFF THE POWER PUTTON

 

[DLBurns]

Re: Pics

Originally posted by Cliffman

Okay Men, this is not for the faint of heart. #ad




Dave, my suggestion is to get rid of the EZ and get the Comp and and DD3's. That way you can SHUT OFF THE COMP when pulling and just use the safe DD3's injectors. When pulling my 15K 5er up a 6% grade with the comp turned off and running on the DD3's my max EGT's are 1200. You just need some self-control and KEEP YOUR FINGER OFF THE POWER PUTTON

Yeah Cliff I think I'm gonna have to do something... how about the TST powermax... understand it adds fuel but not much timing?

I won't go with anything more than EDM 2's... at my age, I don't have the need for speed anymore

 

[Cliffman]

Dave, I don't think the timing is an issue unless you’re pulling a lot of weight and that's not a problem because you can turn off the box therefore eliminating the timing all together when pulling. Don't know much about the EDM 2's are they similar to the DD2's. I like Diesel Dynamics because I’ve been to there shop and I’ve seen first hand how much research goes into there product. That’s not to say that the EDM’s are not just as good, but I just don’t know.

 

[DLBurns]

???

Originally posted by Cliffman

Dave, I don't think the timing is an issue unless you’re pulling a lot of weight and that's not a problem because you can turn off the box therefore eliminating the timing all together when pulling. Don't know much about the EDM 2's are they similar to the DD2's. I like Diesel Dynamics because I’ve been to there shop and I’ve seen first hand how much research goes into there product. That’s not to say that the EDM’s are not just as good, but I just don’t know.

Cliff, I don't know anthing about either one

I think I read to much:--)

... The Tansfer Flow tank and FASS system has put a serious dent in my "FUN" money account for awhile, so the injectors and or new box are gonna have to wait awhile.