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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Seems it would be easier to test the WG on the car by listening or feeling when the WG valve starts to open if the car is running instead of removing it and watching the valve's opening visually on a test bench.

I am far from a WG expert but if exhaust pressure were a factor then to be accurate we would probably have to test it on a dyno at full boost as pressure in the exhaust before the turbo can be 50% - 70% or more of boost pressure and probably increases with HP and or RPM.

By the WG's design, pressure is against the head of what is basically an exhaust valve but the key is that pressure it trying to make it past the valve seat. I do not think the pressure against the top the the valve actually pushes the valve in any way to change or restrict its opening pressure.

Again, I do not know for sure but I suspect the factory procedure might be more one of convenience.

I am thinking there are two things basically relevant to what boost a WG will retain. One is the spring tension, the other is the capacity of the WG vent. If it more open than Porsche expected like with out its connection fittings, it will take more pressure to open the WG. This might be why it could take more pressure on a bench to open it.
Old 04-18-2010, 08:50 AM
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