i just got a 94 cummins with alot of mods and i was wondering what a safe temp for the egt and how long i can keep it there

 

No more than 1400°

 

You will hear lots of different responses to this and the real answer is that once you have a modded truck, you are running much larger risks. I would make sure never to sustain over 1250 and not peak over 1400. There are people here who have seen much higher temps and got away with it but personally, I like to play it safer. There is no set in stone rule.

 

If you are towing, sustained temps over 1250 will start to scuff the tops of the piston crowns and cause cylinder damage as has been reported in many forums. Drag racing, dyno runs or fooling around with temps of 1400 are said to be OK. I have had mine well over 1500 by accident (throttle spring broke) and I don't know of any damage yet. But towing I pull out of it anything over 1250.

 

The "guidelines" are not to exceed 1300 degrees if your EGT/Pyrometer Probe
is in the exhaust manifold and no more that 1000 degrees if the EGT/Pyrometer is in the downpipe.

Hope this helps you some.

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John_P

 

Fantastic point, John. Noting the location of the thermocouple is imperative to knowing the "safe" limits of EGT's. Nothing worse than thinking you are running at 1300, when you may be as high as 1600 or more.