Engine/Transmission (1994 - 1998) smaller exhaust causing higher EGTs?

[Warhorse]

My '97 2500 (auto, 4x4) has only a 2. 5" exhaust running from the muffler to the tailpipe. It was installed after the original pipe self-destructed. Since getting my EGT gauge working recently, I've noticed EGTs in the 900-1000+ range when going uphill at 70-75 mph, with no trailer and nothing in the bed--just me and the dog. The engine is turning about 2000-2100 RPM at 75 mph. I have to back off considerably to lower the temps back below 900. I did notice that the temperature would fall a bit when I turned the overdrive off when the engine started to lug at about 55. I don't remember having temperatures this high in the past. Is this smaller exhaust causing these temperatures?

Thanks!

Paul



PS--I just turned over 300,000 on the original engine and transmission (yesterday, in fact). Other than a 48-state intake manifold, there are no modifications to the engine.

 

[BHanna]

I would think a pipe that small could cause that. The volume of a tube increases more than you might think with increasing diameter so a 2. 5" pipe flows a lot less than a 3" or 3. 5" (not sure what 97's came with). 900-1000 degrees shouldn't damage anything though. In fact, it probably keeps carbon from building up. Of course if you tow it may be easy to get the EGT's too high.

 

[DValentine]

Is your probe pre or post turbo?

 

[Warhorse]

It's pre-turbo.

 

[GAmes]

I've noticed EGTs in the 900-1000+ range when going uphill at 70-75 mph, with no trailer and nothing in the bed

Sounds pretty much in the normal range to me. How much boost, 10-15?



In case you didn't know, stock was 3 inch, good to 400hp according to Joe D.

 

[Warhorse]

I'll have to check boost pressure. I think it was about 10-15.