How much EGT is too much EGT??

[Jayco36REQS]

What is the recommended max EGT you should stay away from??

Just did the dual fuel rail to the back of the motor using 5/16" lines... (same as stock), and dropped to a #22 fuel button... (stock was a #32), and added a digital Pyro. I figured red led numbers was easier to see than a dial gauge. It also have customizable max and warning lights I can set for whatever I want. I didn't touch the screw or shims.

The truck seems to run smoother and accelerate faster.... it shifts much faster from take off, and seems to not downshift on the same hills it used to.

Only one evening driving it, but so far on WOT on flat ground it will hit 1,040 deg EGT.... on a short hill lugging it hot 1,140 deg EGT... I backed out both times it when over 1,100.

I'm going to put a new air filter in it and maybe mount my new muffler as well. I got a new one off a M916 as a surprise in an GL auction. Hoping it flows a little better.

 

[patracy]

I assume we're talking a NHC-250 without a turbo right?

 

[Jayco36REQS]

I assume we're talking a NHC-250 without a turbo right?

Correct...

 

[swbradley1]

I thought you were putting a turbo on it too.

 

[royalflush55]

I have a pyrometer on a John Deere 4 wheel drive tractor rated at 235 drawbar HP. Engine HP is 275. This is a 6 cylinder turbo with inner cooler Under normal load it runs about 900 degrees. I am told to not pull it hard enough to reach 1000 degrees. Above 1000
degrees metal goes to doing funny things! As a comparison it seems like your temps are pretty high!

The coolant temperature will not change between 900 and 1000 exhaust temps! You really need to rely on EGT instead of coolant temps.

 

[gimpyrobb]

Most folks say 1200 is where you want to stop. Thats where aluminum melts. I have run my deuce for hours at just under 1200 and when I just did my head gaskets, everything(pistons, injectors, etc) looked fine.

 

[patracy]

My personal guidelines...

NA diesel = 1200F EGT max, watch coolant temps.
Turbo'ed NA diesel (missing squirters) = 1150F EGT max, again watch coolant temps.
Turbo'ed diesel = 1250F, watching coolant temps of course.

Aluminum melts at 1221F. However the pistons in these engines aren't pure aluminum. They're an alloy.

While it's apples to oranges. Cummins tests/rates the ISB series engines to run 1350 all day long. 1450 in bursts. I have not found any documentation as to the rating of the NHC 250 yet. However I know in the military rating system it's rated on max power output in a prolonged period. So that 240hp rating of the NHC is at 2100 or so RPM under load for a long period of time.

I'm kinda surprised your truck had a #32 button in it. Everyone else has had 27's. I know many have gone to #22 and 20 buttons with a stock setup and no issues. I feel you're fine with it. Just have to drive by the gauges, which it sounds like you're doing.

After the rally and football season is over. The "SEMTT" is getting a #5 or 7 button and a HT3B. I plan on running it at around 1150F as well.

 

[Tow4]

As pointed out, about 1200F is a good max. Unless you are going to run it there all day, a few degrees one way or the other won't matter. Putting more air through the engine (lower gear) and/or less fuel will drop the EGT on a long hard pull.

 

[Jayco36REQS]

Awesome... thanks for the info!

Yea I had planned a turbo for it.. but the retard that was supposed to do it F'd the plan up and was more talk than knowledge about military trucks. I'll do it after the move...

The air filter is a bit dirty, 1/2 of it that is.... I'm going to swap it out and see if there is any effect of a bit more airflow.

Speaking of airflow... I was talking to a guy who had an "electric turbo" on his NA truck... anyone ever heard of these? From what he was describing, it was some sort of an electric fan plumbed into the intake system after the filter that he could flip on during a long hard pull... he said it added more air to the motor, (around 4psi boost) for a bit more power and cooler EGT at WOT? Never heard of a contraption like that.

 

[Jayco36REQS]

I'm kinda surprised your truck had a #32 button in it. Everyone else has had 27's. I know many have gone to #22 and 20 buttons with a stock setup and no issues. I feel you're fine with it. Just have to drive by the gauges, which it sounds like you're doing.

I plan on running it at around 1150F as well.

Yea I was surprised by the #32 button as well. Mine is a Nov 09 rebuild... so not sure if that has any impact on it. The good thing is the rear plug for the dual fuel mod, just came right out with zero issues. A little lapping compound and it backed right out without needing to heat it or over-force. The dog house on the other hand was a MAJPOR PITA!!! The insulation on the firewall was the worse to deal with. I ended up having to pull the entire gauge cluster panel out enough to get my arm in there, and also remove the heater duct so I could cut the insulation around the bolts, and reach the bolts. But... the good thing is I found my pesky air-leak I had been having behind the gauge cluster... simple loose clamp on an airhose!

 

[gimpyrobb]

The stock air filters are washable. I have done it a few times. Wow does that water get nasty!

 

[Jayco36REQS]

Ok... I messed with the truck more today... I hit the highway and got it moving around 65-68mph, and going up a longer hill on the highway it climbed to about 1270... with only a slight trail of smoke.. not black.. but just a slight trail. The engine temp never budged past 185-190 where it always is. I'm wondering if my EGT gauge might be a bit off? I would think that pulling 1100-1250 EGT for 3-5 min it would have increased the engine temp as well... even a few deg?

Anyway to check the EGT gauge for accuracy?

 

[Tow4]

Unless the cooling system is marginal, I doubt you will see the temperature climb very much in 3 to 5 minutes. I've done many long pulls with my F350 out west at high elevation and the coolant temperature never changes. Sometimes the fan engages but that is probably more because of the AC.

You can do a test of your calibration by using boiling water. Water boils at 212F at sea level, you can correct the boiling temperature for your elevation and obtain a good calibration point. Make sure the probe does not contact the water container. You can also use crushed ice in a slush to get very close to a 32F point. If you are close at those two points, you are probably OK. If you want a test point closer to 1200F, there are probably commercial calibration service companies nearby you can use.

 

[rebelqwes87]

I'm kinda surprised your truck had a #32 button in it. Everyone else has had 27's. I know many have gone to #22 and 20 buttons with a stock setup and no issues. I feel you're fine with it. Just have to drive by the gauges, which it sounds like you're doing.

Mine also had a #32 in it. Walkerhunter and myself changed it out for a #22 just before the rally.