Maximum safe EGT?

[GTX_Joel]

Greetings folks,



I just got back from a 4500 mile round trip from Minnesota to California. I was pulling my enclosed trailer, about 9500 pounds loaded. I took the southern route to avoid major mountainous areas, but still hit alot of smaller hills and 6000 foot elevations.

The ambient temp was 90 to 100 degrees lots of the time. Blew 3 trailer tires.



I was getting alot of 1200 + egts, especially on grades and at altitudes. I generally kept my foot out of it to keep egts at 1200 or less. This would be about 15 pounds boost, in overdrive at 60 to 70 mph. slowed to 55 or less on some grades, dropped it out of overdrive sometimes and got down to 50 mph.

I could develop 22 pounds boost and go faster, but the egt would shoot up to 1300 or even higher, so I would slow down. I always want to go faster. How hard can I push this egt without hurting anything? How can I lower the egt and gain power at the same time? BTW, it got as bad as 9. 5 mpg and as good as 11. 5.

3. 54 gears in the rear.

 

[DPKetchum]

Bigger intercooler??

 

[BushWakr - RIP]

From the sound of it you're running right on the recommeded max sustained EGT's..... Cummins says 1200*F continuous duty, and ALWAYS allow good cool down time when running at sustained temps like that.

I sure hope your pyro is pre-turbo mounted... . if not then 1300*F and the extra temps per pound of boost means you were in or around 1500*F - 1550*F.....



The only way to reduce those temps are pretty basic... less fuel... NOT !!

More air in... hybrid turbo for example, high relief manifold as in ATS 3 piece... . NO exhaust restriction which it sounds like you've already done...

As a temporary measure you can pull your stock exhaust manifold, gasket match the inlets using care not to thin the manifold walls too much, slight porting of the 16cm inlet ports, again with care or you will reduce exhaust gas velocity and hinder spool up... . open airbox or no airbox with filter down at lowest point near headlight to try and get max cool air... .

Confirm your timing... . the TDC pin can have as much as 2. 5* error due to "sloppy" fit... . remember, if you timing is set at a static 16* and you then run up to/near WOT, you are running a decent amount of advance beyond the initial 16* ..... I'm trying to find out how much actually, but no luck yet... .



Pastor Bob.

Our Lady Of Acceleration Church...

 

[GTX_Joel]

Thanks for the replys.



I have not checked the timing. Can't find a plug wire to hook my timing light to.



Really, I am fairly new to diesels, so I don't know how.



Is 3" exhaust enuff? Would I see enuff benefit in switching to a larger exhaust to justify replacing a perfectly good system?



How about that larger inter cooler and ATS maniflod? Where do I find them and how much $$ are they? I'm going to Bristol Tennesee in October, so more mountain climbing is on the menu.

 

[bflood]

Thanks Joel for posting this question because I am at the same position you are with ETG's. I'll be following this thread with keen interest.



I frequently tow about 14K pounds (2 John Deere antique tractors for pulling competition on a 7ton gooseneck) up lots of hills. I'm not doing too bad but on a hot dry day especially, I have to back off the throttle, or shift to 4th, for the sake of EGT's. I'll let'r run up to 1250* (preturbo) with very brief jaunts to 1300* if I'm almost over the hill.



FYI, my setup:

* Pump turned pretty much up all the way with all four adjustments.

* K&N filter inside the stock box.

* Advanced timing (by "ear", don't know the numbers)

* Straight pipe, 3", exhaust (no cat or muffler).

* 16cm2, non wastegated, housing.



Seems like I've done most of the easy stuff and now have to get patient and fussy.



Just for clarification, this rig pulls like a "scream'n eagle". I can backoff the throttle due to EGT's while cruising past the gassers on hills.

 

[Mgrant]

I had the same problem with my truck when towing heavy loads with the 16cm housing. My pyro is post mounted, but it would still get up to a 1000* and I would have to downshift to keep it tached and boost below 15 psi. Since then I have switched to the 12cm wastegated and I can't get my EGTs above 800* at any RPM and throttle. I found out the 16cm works great for the high rpm drivers and the 12cm works best for the low rpm pullers.



Mike

 

[dpuckett]

Mgrant-

Not so fast on your EGT theory. With a stock 18 cm housing on my 91 and a PDR HX35, I NEVER saw 900* post turbo 3/4"; 27psi. Moved the T-couple into the manifold, and could get into the red zone easily. Proof that the old 1 psi=10deg error theory is wrong. With teh wastegate in there, the difference is even greater. But you are right about the 16 being better suited for higher RPM than the 12. I've proven that with my 4. 10s and enhanced fuelling.

GTX Joel-

If you are going to go under 60 mph in the hills, I'd kick the OD out. MOre efficient TC usage at higher RPM, more boost to cool EGTs, and you may actually use LESS fuel than if you lugged it in OD at 60-65.



Everyone-

I plan to get a 2nd gen cooler and put it in when I get the $$$ Not towing at the moment, and can keep it under 1300, so it isnt a real issue yet. I'll take pictures and post when I get it done (Christmas?) Anyone know where I might get a 2nd gen intake horn to accomodate the bigger cooler lines?



Daniel

 

[Mgrant]

Hi Dan,

The reason I went with the 12cm is due to high altitude pulling and have enough low end power to tow on windy roads without having shift constantly, which here in Idaho can get very tiresome. I've driven heavy semis all my life and I can do know for certain that the newer low, rpm wastegated engines are much more fuel efficient than the high winding engines of old and I'm very happy with the way the 12cm housing performs. As far as post mounted pyros, I mouted in the exhaust brake for convience, accurate turbo cooldown temps, and I've actually seen the results of three damaged engines due to the pyro comming apart and munching the turbo. On one engine in particular, a DT466, the turbo was damaged so bad that the compressor wheel came apart and ruined the intake valves, heads, and pistons.



Mike

 

[bflood]

Originally posted by Mgrant

I had the same . . . . I found out the 16cm works great for the high rpm drivers and the 12cm works best for the low rpm pullers.



Mike

This might suggest that a 14cm2 wastegated turbo housing might be closest to "the best of both worlds"



Anybody want to add their 14cm2 housing experience to the discussion?

 

[GTX_Joel]

The truck won't go over 58 mph in 3rd. So i had to use OD most of the time. Maybe I should turn up the high idle so it will go 60 - 65 ish?

 

[bflood]

Looking for input from owners with 14cm2 housings

Originally posted by Mgrant

. . . . . I found out the 16cm works great for the high rpm drivers and the 12cm works best for the low rpm pullers.



Mike

This might suggest that a 14cm2 wastegated turbo housing might be closest to "the best of both worlds"?



It would be interesting to get some opinions from people using a 14cm2 housing.

 

[DPKetchum]

My old 93 w250 I just sold had Banks exhaust,42H. P. injectors from ADT,14. 2 waste gaited turbo housing,Banks intercooler,K&N air filter,fuel screw turn 3/4 of a turn and high idle screw 3 turns. Pulling 10k steep inclines never saw any higher then 950/975 egt. Truck pulled great and real strong. Smooth idle,start in any temp weather etc. Before injectors with same setup only saw a max of 850/875 egt nomatter how hard or long a pull. Almost NEVER had to slow up and kick off o/d. Just kept it romped!Did the bigger intercooler make the differance?Fellow that bought it wanted to know about fuel mileage. I never checked it. He called and said that from Athens Georgia to Knoxville Tenn. with cruise on all the way at 70mph it got 17mpg with 4. 10 gears. That includes some 4 percent grades etc.

 

[JStraw]

I had a 14cm2 on my rig for a while but it really felt restricted at interstate speeds of 70-80 mph. Can't honestly say that I noticed more umph. I switched back to the 18cm2 and now have my tire frying 100mph truck back. I know others have unquestionably felt / have noticable improvements from going to the 14cm2. In my case it didn't prove to work out for my needs.

 

[DPKetchum]

Mine would pull 21/22 psi of boost almost from a dead stop to almost 100mph with no problem