Thanks for taking the time to reply, Geoff. I actually just emailed you guys today, asking about the wait on 7163's, I'm the guy with the @rit.edu address. Glad to hear some solid facts from someone close to the source; that's awesome they were able to keep similar inertia on a wheel 5mm larger. 2-3s in Indy is huge too, 2.5s would be a 6.7% difference on last years 39.658s best lap at Indianapolis. 6.7% improvement on my autocross times would be a ridiculous 4 seconds on a 60 second course. Not that I'm expecting the same improvement on a small autocross course but I'm still thoroughly expecting the 7163 to blow my 2871 away.
Any builds coming up with 7163's that you're aware of? I'd love to see more real world results.
Quote:
Originally Posted by PoorMans180SX
Aasbo's 8374 used to be internal gate, but they welded it shut and welded the wastegates directly to the turbine housing. (This is when the IWG were still investment cast).
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Any chance they published before and after graphs? I doubt they did but that would be perfect to see what effect going external has.
According to BW's Matchbot, you need 42% wastegating to hold 25psi at 7500rpm on a SR20 and exhaust manifold pressure at that point is 35psi. I'm sure 35psi is enough to crack the wastegate open a bit but can it really push it open more than 42%, thus causing a drop from 25psi? I'm gonna venture a guess at no. Once that wastegate cracks, the exhaust is going to lose a lot of its pressure and I can't imagine there being enough pressure still to push it over 42% wastegating.
This is a pretty important question for me, because its a $400+ difference between internal and external on a twin scroll setup. Geoff, any back to back IWG vs EWG dynos on an EFR that you're aware of? I'm sure the externals are better but if the internals are close then I'll put the $400 towards something else.