Turbo Boost

[JFortune]

I have and 2003 6sp 4x4 4"exhaust MBRP, Edge Juice w/ Attitude. Question is, I was hauling a load of peanut round bales this week end attitude on #2. And in 5th gear pulling a hill my boost was hitting 36-37 psi. Which the attitude kept alarming(36psi is the factory setting alarm for boost on the Attitude) so I backed out of it, which really sucks when trying to pull a long hill. . What is the most PSI I should run constantly, safely? What is the max this truck will probably take if I get into a pinch? Thanks



John

P. S. Even when pulling can't seem to hit over 1100* EGT pre turbo which is awesome. .

 

[ENafziger]

If I remember right, Cummins max recommended boost for these engines is about 55 psi. I would err on the side of caution and feel more comfortable running around 45 for daily use. However, I recently installed some mechanical gauges, and realized I have been hitting 60 psi for several months without knowing it! I've backed down now, but haven't noticed any ill effects.



I believe the 55 psi limitation is due to the stock head gasket and head bolts. However, at higher boost pressures, valve interference also becomes something to consider. To do 55 + psi safely, I think studs and valve springs would be a good first step. --Eric

 

[staarma]

Actually I wouldn't run that turbo past 32-35 PSI. The turbos were different on the 555 motors. Anything past that boost and you are out of the map for that turbo and not doing much but blowing hot air.