EGTs, how hot for short runs.

[CumminsPower98]

Well I got a G-tech a few weeks back so I have been doing a bit of playing. My problem is that my egts go through the roof at high rpms. You can see what the truck is in my sig. My question is how much of a problem is it to run the egts this high for a short dyno run like this? Has anyone done much of this and then had to tear it down so you know if there was anything hurt or not. I am pegging my gauge past 1600º in 3rd and 4th gear for a short time. I am guessing that I'm not hurting anything but I don't like seeing that gauge read that high anytime. I know I need a bigger turbo and all that but can't do it for who knows how long. I'm showing a little over 300 hp on the G-tech. The truck weighs in at 6,980 with a full tank and me. Any thoughts would be great.

 

[The patriot]

We have almost identical trucks.

I think you should be making more than 300, depending on how "custom" the fuel plate is.

I wouldnt want to run 1600 deg.

I have my probe post turbo, and I have to run the crap out of it to get it to 900.

Eric

 

[Roger rodbolt]

Originally posted by CumminsPower98

Has anyone done much of this and then had to tear it down so you know if there was anything hurt or not. I am pegging my gauge past 1600º in 3rd and 4th gear for a short time. I am guessing that I'm not hurting anything but I don't like seeing that gauge read that high anytime.

CP98,



A factory Cummins' instructor was asked a similar question, how much heat can a Cummins take and for how long? His answer was "remember, you can bend a paper clip back and forth, back and forth, but when it breaks... ... you can't put it back together!



I'm not sure that there really is an specific answer because of different loads, boost levels and engine condition but if you are going to run high egts, ceramic coated pistions are recommended and expect shorter valve life and head cracks. For non competition trucks you will ultimately save $'s by spending to lower egts upfront. Hope this helps?

 

[pwknapp]

Strick9 posted about cracks in his turbo when he diassembled it after a few high egt runs.

 

[CumminsPower98]

Next time I make a run I will see what I can get out of it keeping the egts in check. I still have the stock 215 injectors too and my max boost with the waist gate unhooked is 36 psi. My cousin's truck is a '97 and the same as mine except he still has stock exhaust. He got 336 hp on the same road with a little egt control. I think his truck might be timed. When he got it the plate had been moved. Does anyone think timing would make this much difference? His plate is the same as mine but I guess I can't be certain they are in the exact same spot. We get the same temps while running down the road together. Thanks for the replies, I will try to keep the temps down even for short runs as I can't afford to kill this thing.

 

[Strick-9]

I recently tore down my engine.



I found 5-6 1/2" long cracks in my head.

I found 14 cracks in the exhaust housing of my HX-35.

I found 3 cracks in the exhaust housing of the HX-40.

The tops of one of my pistons had some 'porous' regions where it looked like it had begun to melt.



This was with 'short' blasts of high EGT. Never more than 12-14 seconds. (1/4 mile)



Enjoy,

-Chris

 

[illflem]

Simple rule of thumb is you can run all day at 1250° pre-turbo, anything higher should be limited to under 60 seconds. Temps over 1500 should be totally avoided, your engine may survive it but it's life will be shortened.

 

[JMichelson]

Post Turbo

Illflem, Can you convert those numbers to post turbo.

Thanks, Jeff

 

[The patriot]

Jeff, I've been told to figure about 400 deg difference to be safe.

The exact # varies from truck to truck.

Eric

 

[pwknapp]

Jeff, get a tap and drill and put your pyro thermocouple pre-turbo. I finally did mine and noticed the diference ranged all over the spectrum depending on conditions. Couldn't feel safe hauling a good load guessing what the temp might really be. My . 02

 

[P Madrid]

Pre-turbo or post-turbo

OK guys, I know this has been address several times on where the best place for the thermocouple should be but can any one help out on this one, one more time. In school and Cummins training the rule was: Post turbo - Install thermocouple at a distance away from the turbo outlet equal to the diameter of the exhaust pipe. I do not remember the Max Temp. On pre turbo it was said that a false reading could be given due to the reading of only half the engine cylinders, in this case #1-3 or #4-6. I have also seen set ups with two thermocouples and one with six, one for each cylinder on a custom exhaust. My thermocouple just arrive and I would like to go post so please educate me on the different choises. Thank you, Pablo

 

[illflem]

Pablo, I would reconsider going post turbo. The only reason to go post would be for shutdown temps or fear of the probe falling apart and damaging the turbo, something that rarely happens. Pre turbo is much more responsive and gives a better indication of the actual temperatures in the cylinders. A friend who has two pre turbo probes sees very little difference between the front 3 and rear 3 cylinder temps, hardly worth it.

Do it this way



#ad

 

[RedRamer]

Here's a good article on where to put the pyrometer.

http://www.dieselinjection.net/articles.html

It's very long but go down to Manifold Pressure Guage

and read the prargraph right above it. Or search the page for "pyro" and it's the third hit.

This guy says that in 21 years they have never lost one pyro placing it in the exhaust manifold using Hewitt thermocouplers and most are those.

Drilling and taping the manifold is easy. It drills like butter.

I used a very heavy oil to drill & tap it and the shavings were caught in the oiled drill bit & tap flutes. no problems...

Just take the air filter hose of and check that the turbo spins after install.

 

[Strick-9]

I've lost a pyro probe that was mounted pre-turbo. But everything that can go wrong has with my truck.



I pulled it off one day to port the manifold and noticed the tip was gone!



No damage to the turbo. I thought it might have stuck in the turbo exhaust manifold because it couldn't make a tight enough bend to get around to the wheel.



Who knows. I replaced it with a new one in the same location and no problems yet!



But they DO break off.

-Chris

 

[K_Arts]

Chris,



Before you tore down your engine, what kind of EGT temps were you seeing?



Kev

 

[Strick-9]

K_Arts,

My spa gauge doesn't read higher than 1747°.



It was well above that. When the truck was running good I could peg the gauge in 4-5 seconds from a standing start or going down the freeway. Didn't matter.



-Chris

 

[Snow man]

Chris,with your EGT's ,I would expect those problems. I have hit 1625 before,so its time to lower my EGTs too. Its amazing you didnt melt a piston right thru.

 

[tschwab]

You might want to consider a different plate and maybe the aFe Mega Cannon air intake system to lower EGT's. I think you will notice a much more accurate read with the probe "pre" turbo.

 

[HEMI®Dart]

Has anybody "Knife Edged" the pyro probe to allow for better exhaust flow?

 

[Don M]

Bill, I just moved mine out of the manifold and into the elbow to deal with restriction.



BTW,



I broke down my spare cylinder head from my truck over the weekend and have found some pretty interesting stuff.

All the exhaust valves are pitted pretty bad . All the valve guides were worn out. Evidenced by the bad oil build-up on the tulips of the intake valves. Thick, black, yukky stuff coated them. This was no doubt hurting the flow and seal of the valves in their seats.

Also, I was lucky in that I had no cracks in the head. Not even in the general areas they always crack in. Next to the valve seats and injector bore area. Not a crack. But the relatively low EGT's I did run killed the exhaust valves. I never ran over 1500 degrees with this head with the probe in the manifold. Yet it still smoked the valves. So, most guys are not going to kill their engines right off the bat with high EGT's, but it can creep up on you and slowly damage stuff.





Don~