A buddy of mine is having trouble building boost. He says the highest is 14 lbs. I told him that it sounds like a leak somewhere between compressor on turbo and intake man. His truck:
2002 Cummins - only mods that I know of: Quadzilla.

Any comments - ideas - suggetions?

Thanks

 

Check for leaks around the boots/clamps or the boots themselves. Also check for leaking around intake horn gaskets, intake manifold gasket.

Either that or his Air Filter is really really dirty and needs changing.

 

I've seen cracked boots, loose clamps and on the big trucks leaking aftercoolers. We had special plugs we made from round tube that would fit in the rubber boots so we could cap off the aftercooler, then it had a 1/8th npt plug so we could hook up an regulated air gauge so we could put 10-15psi on the cooler and listen for leaks.

 

I made a pressure tester that is perfect for diagnosing these problems. It simply attaches to the turbo inlet, then you pressure it up to 15-20 psi with shop air, and in 20 seconds, you've found any boost leaks you may have. There is a picture in my gallery.

 

Thanks all. Found the leak. Should of known the natorious left front fender rubbing through the boot.