how many degrees to add on egt reading?

[bmoeller]

That might have been me. I have never seen more the a 200° split in all conditions. It all depends on were your probes are relative to each other.

Depends on where you have the probe in the manifold too. Rear 3 tend to run hotter than the front 3.

[bmoeller]

I would say it is a little low though.

I think so too, but seems to be a decent guesstimate for a stock engine. Putting too big of a turbine housing on it would make the EGTs higher in comparison.

[cougar]

The "pre turbo" location has been somewhat standardized and most of us use this location. Temperature readings from an accuracy stand point are subject to far more criteria than just location. That said, even a standardized location isn't consistently accurate one vehicle to the next. On the "post turbo" side, there is no standardized location mainly due to the various number of turbo and exhaust combinations we play with. The only thing you can count on is that the further from the heat source (the combustion chamber) the colder the exhaust temperature gets. What location in the exhaust system did Cummins use to base their 1250°F 100% duty limit on?