'66 Slant Six Turbo Build

Thanks for the info on your pistons. I kind of figured. I really love turbo motors and whenever I see builds like yours I get very tempted. In theory, with an HX35 from a Cummins, a 500 horsepower at 5000 rpm slant should be pretty straightforward with about 25 psi of boost. But that's not the plan for my Valiant.

Boost creep is a very common problem with internal wastegates on small turbines, especially if you are trying to keep boost low. In your case I imagine that the hot side is too small for your application. You can switch to an EWG but I bet you'll still have some problems with it. Better to step up to a larger hot side or larger turbo.

And you are more or less right on the flow vs. pressure thing. I'm not an engineer but I have done a lot of reading (and writing) on this topic. If you pick the right turbo you can get more power with the same boost (since the larger turbo is running more efficiently with a lower P/R). Or the same power with less boost. but then you might run into more boost creep issues unless the hot side is properly matched to the engine.