[Dieselwrencher]

Originally Posted by eric28miller

There's an internal waste gate on the smaller turbo and nothing on the larger one, but i'm guessing the smaller phatshaft needs to open up when the larger s474 spools up. I try calling industrial injection but I can never reach anybody.. A few threads on the cummins forum said they had to drive a couple hundred miles before the turbos were broke in? I've never heard that before. What are you running for boost on your set up?

I wouldn't believe what most of those guys on cummins forum say. There are bronze bushings and chrome moly sealing rings in the turbo center section as well as a bronze center bearing and a steel sleeve the turbine shaft goes through. These pieces may loosen up after some wear, but I wouldn't call that break in per say. S300's all seem to become pretty loose compared to holsets and garretts from what I've noticed. Haha Anyhow, You should still be getting the normal amount of boost from the secondary unless they have some monster turbine housing on it. If it's a phat shaft is it a 64/71 or a 62/71 and do you know if it is a .80 or .83 ar? The turbos I have on my car, the secondary is gated to start opening at 20psi and have it fully open at 25psi. It'll still make over 70psi not WOT with the modified 75mm GT4294. I'd first try to see what your internal gate is set at and make sure you have no boost leaks. Make sure you have o-rings on your compressor housing outlets as well.