I just returned from my mechanic where he installed a boost gauge for my 8.3 Cummings, 240 horsepower. Never had one before. Anyway, the max boost PSI coming home was 23-24 in 3rd gear going uphill. It mostly hovered around 10 on straight road. Are these normal readings for my motor?

I am interested in the feedback also. My 8.3 has no EGT or boost gauge. These are high on my list to get in place to be able to monitor engine loading.

Max boost pressure is normally about 26-28 psi, limited by the waste gaste. At partial throttle, the boost will be lower. The part throttle boost at various rpms would be good to know indeed.

When I get gauges I will report on the results.

Found this one from Billy T's coach:

Cummins ISB 5.9L
Max boost about 22psi although when I had full HP saw 30psi
Normal about 10psi at cruise
EGT runs 900 to 1000 and straight and level and up to 1300 on a hard pull.

Our waste gate is set to open at 30psi

quote:

Originally posted by Gary Carter:
Cummins ISB 5.9L
Max boost about 22psi

Our waste gate is set to open at 30psi

Ummm not on a stock 5.9L 190-230 HP Cummins. Maybe on yours with the changes you made BUT a stock waste will open 20-22 PSI.