Maximum safe boost?
 

With the last round of upgrades to the cummins in my 93 Dodge 1 ton Dooley, It will make 33 pounds of boost. That's about double what it originally made. Am I looking for trouble?

Modifications include a bigger turbo, bigger injectors, turned up VE series pump, four-inch exhaust.
What is the most boost that these engines can handle and remain reliable?
What are the common failure modes? I have an EGT gauge.

Thanks, Joel

What size turbo are you running? Youll be fine, no need to really worry about getting headstuds until about 50 or 55psi :tu: . I wouldnt go over 50psi without them.

It's an HE351CW.
Thanks for the advice, I'm glad I don't need to worry about blowing out my head gaskets at 33 PSI.

No problem. Yah there nice to have which is the next thing i plan to purchase besides a p pump from my friend next month. But im pushing 40psi with a Hx35 , 45psi though before i had the actual timing of the motor jumped a tooth after 5x16s were put in. Ovbiously youll need them later, but nothing to worry about, all depends on what your wanting to make power wise :rocking:

40 is about the point when some reports of blown head gaskets start happening. Somewhere about 35, temperature of the boosted air starts having an effect and performance starts to diminish. Added cooling such as a larger intercooler and/or water injection helps to regain power lost by heat.

Thanks for the helpful replys! I'm plenty happy with the power where it is at, not going with any more. As long as 33 lbs is safe, I'm happy.

Attachment 34788


Question for you, NKY 1stGener: how did the steel gears in the cummins jump a tooth? I don't quite understand?

He opened up his timing case and jumped a tooth that way.

If that is what your towing, I'd recommend water/methanol injection. At a low volume it will really help keeping your EGT down. You can get a complete kit for like $400.