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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
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Originally Posted by T77911S View Post
been thinking about the exhaust flow and WG spring thing.

the spring is pushing the valve closed. that is a constant. the boost pressure from the IC is trying to open the valve, BUT....what about the exhuast pressure on the bottom of the valve?
thats pushing up on the valve trying to open that too, no?
so if the exhaust flows more freely out of the muffler then there is less exhaust pressure under the valve pushing it open thus requiring MORE boost pressure from the IC to open the WG.
i guess i will find out for sure. i have a .8 and a.6 spring on the way.
Now you are thinking and starting to see how the whole system works!

The exhaust backpressure does add to the force slightly opening the valve. But it is negligible to the force from boost on the wastegate diaphragm. Plus it no longer has any effect once the valve cracks open breaking the seal with the valve seat and pressure equalizes on both sides of the valve head.

1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 06-04-2013, 09:13 AM
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