Cummins diesel

Winterwolf227 wrote:

Folks have reported this should be between 200F and 600F cooler than the "pre" turbo values. This is the problem with using a "post" turbo EGT gauge. It is hard to know what the maximum numbers should be. But, I would think using 900F or so as the maximum values would be in the ballpark, usually.

I have a post turbo EGT reading of 900 all the time, and that is under easy throttle with 2200 rpms in 3rd gear. So I would think that 200-600F cooler than pre turbo is off. I do believe it is cooler, but not by that much ?

I agree that under "easy-throttle" operating conditions, a 200F differential factor is probably a realistic value.

The up-to-600F differential factor comes from folks who have pyrometers installed in both "pre" and "post" stations on the same vehicle. I have seen their reports indicating that under very heavy engine load conditions (like towing up a long and steep mountain grade) the "pre" gauge initially can read up to 600F higher than the "post" gauge. After the grade, things can settle down closer to the 200F differential value.

I like the pre-turbo position because it shows the true instantaneous temperatures being experienced by the engine. It does not have the guessing factor that the post-turbo position requires under heavy load. I drive by the pyrometer when climbing mountain grades, downshifting and/or slowing as I hit the 1250F pre-turbo EGT limit.