Engine/Transmission (1994 - 1998) Advise on EGT Reduction

[BrentL]

Trent,



EGT's become more of a problem in higher elevations, generally above 6,000 ft and pulling 14K plus in 5th gear and above 1800 rpms.



I have pulled over 20K at sea level with minimal EGT problems. It's the thin air that seems to be my real enemy. Hopefully a little timing adjustment will help some.

 

[Jim Fulmer]

I also agree here that timing at 15. 5-16. 5 is about right for almost everyone, if your going to pin the pump, pull the gear and back the motor up to advance the timing then I suggest a few things, break the T/Q on the pump nut first before you pin the pump, use the formula diameter times (pie) 3. 1416 divided by 360 for the number then times the degrees you want to advance and it will give you a number in tenths of an inch, that's how much you will back the motor up, then do the normal clean the shaft off, blow it dry ect, then slightly snug the nut and washer back on before pulling pump pin so it doesn't move. 18-20 degrees is fine if you have the fuel and headgasket setup to handle it, after 20 you start taking away from the bottom end and putting it on the top.



Jim

 

[K5IP]

BrentL

I agree with Jim's approach. The actual answer is:

9. 25x3. 1416=29. 05inches (circumference)

360/29. 05=12. 39deg/inch at flywheel.

or 12. 39x. 25=3. 1deg for 1/4" at flywheel

Rog

 

[Joseph Donnelly]

Timing helps if done right. From the above posts you can see there is lots of room for trouble getting this adjustment done right.

So here is a list:

1. bigger turbo like DD Jammer, HX40, etc. Not just a compressor wheel upgrade, but the whole thing.

2. ported head (I do my own)

3. camshaft; I like the DD best



each of the above should help 150-200 deg. F.

 

[HEMI®Dart]

Don't overlook a 24 Valve Intercooler for EGT reduction. It dropped my idle egt by 50°. Try to get a '01-'02? They are the bare aluminum ones. I got mine off eBay for $200 clams and it looked brand new.



Good info: https://www.turbodieselregister.com...s=&threadid=73597&highlight=Valve+Intercooler

 

[mschoenheider]

In my last truck (1996 5 speed with a #11 full forward), I was getting hot (1300 or so) while towing between 5000 feet, and 10,000 feet. I installed a HT turbo stage 3 compressor wheel and housing, and it solves my high EGT problems.



PSIA = PSI Absolute

PSIG = PSI Gauge

PSIA = atmospheric pressure plus gauge pressure

Pressure ratio = output pressure/input pressure



At lower altitudes, the compressor upgrade alone may not help too much, but at high altitudes it seems to work very well. At higher altitudes, you are starting out with lower atmospheric pressure than you are at sea level. Roughly 12 PSIA at 5500 feet versus 14. 7 PSIA at sea level. So in order for a turbo to generate 30 PSIG at 5500 feet, it has to create a pressure ratio of (30+12)/12 = 3. 5. For that same turbo to generate 30 psig at sea level, it onlt has to create a pressure ratio of (30+14. 7)/14. 7 = 3. 04. The mass flow rate is very slightly higher for the turbo at sea level (because 30 psig is 44. 7 psia at sea level and only 42 psia at 5500 feet), but basically identical to mass flow rate through the turbo at 5500 feet in that example, so therefore the exhaust housing size does not need to be increased, howerer the compressor houssing and wheel need to produce a higher pressure ratio, and therefore they need to be larger.

 

[Turbo Thom]

mschoenheider... ... ... ... . say that again?



. . Preston. .

 

[K5IP]

Well said. Thanks for the nice example.

Rog

 

[mschoenheider]

Say what again? I know it wasn't the most clear reply, but do I'm not sure if any part is ore unclear than any other, do you have specific questions?

 

[BrentL]

Thanks for all the input guys! The timing is now set at 15. 5, and no, the Cummins joint did not set it. Once I traveled 150 miles the shop foreman refused to set the timing to anything other than factory spec. To make a long story short, he did refer me to a local diesel performance shop that took care of business for me.



The truck seems to be much more responsive, much less white smoke when cold, and may even be getting better mileage. Not 100% sure on the EGT's yet. They don't appear to climb as quick.



mschoenheider, so you feel the compressor wheel upgrade to a stage II is worth while, especially in the higher altitude? I may give that a try too.



Thanks again for everyone's time!



Brent

 

[mschoenheider]

I went with the stage 3 upgrade, and it was definitely worth while. The machining to the turbo is very minor and only cost me $30 locally.

 

[SteveMiller]

I have first hand experience with towing at high altitude with a HT Turbo Stage III compressor upgrade and it was a huge help with EGTs. This was with a truck that had a little fuel added by a plate upgrade.



I can see where the upgrade may not do much for mostly stock people at sea level but like mshoenheider said (at least as I understood it) since we start out with less pressure up here we need to be able to push more air to get the same affect as the smaller compressor at sea level.



I will definately plan to put one on my truck as soon as I can.

 

[BrentL]

Thanks for first hand knowledge Steve. The Stage III compressor upgrade is in the mail. I'll have the machine work done locally as well.

 

[Turbo Thom]

Just a little dry humor. I don't have a clue what you said.



. . Preston. .

 

[SteveMiller]

Brent glad I could help and I hope it works out good for you. I'm sure it will.



and Preston... its ok man I dont' think most people understood what he said but it sounded like he really knew what he was talking about or something.



Geeky engineers. J/k Mark.

 

[BrentL]

Stage III compressor and compressor wheel is installed. I couldn't believe how much louder the turbo is with the stage III.

I just took a quick test drive yesterday (15 miles) at elevation of 8,000 ft. so I don't have a lot of data yet.

Although I didn't see an increase in boost, the boost did seem to climb much faster and my pyro much slower. Pyro seemed to peak at 950 on semi flat terrain.



If the turbo sound means anything, it's certainly working harder and moving more air!



Will follow up once I put some weight behind it!

 

[KLockliear]

Cam. Can't beat it. No drawbacks (other than cost - a little more than a bigger turbo). Benefits - better spool up, 200-300* less EGT, reduced smoke, better mileage. A win-win mod.



Dynomite Diesel in WA is even doing a special on them right now.