Originally Posted by
YNOT
4.2 diesel with factory turbo and intercooler is a TD42Ti. If it is factory intercooled then it will have an electronically controlled injector pump so you wont be able to just wind up the fuel manually. TD42T non-intercooled still had the mechanical injector pump which can be adjusted.
EGT's for these older style pre common rail engines are all roughly the same, so on extended periods of full throttle the post turbo EGT's should not exceed 500-550 degrees.
9psi boost is conservative, the factory turbos can safely run at 12 to 13psi, any higher and they start to loose efficiency.
When it comes to tuning a diesel boost and EGT's are only part of the story. Basic things like valve clearences need to be correct, injector and pump condition and pump timing all play their part as well.
I've had a GU TD42T in the past, I had it set to 11psi boost and EGT's maxed out at 500 degrees. It made plenty of torque but was still a conservative tune for reliabillity.
Tony