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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
Posts: 2,235
Originally Posted by RarlyL8 View Post
Bench testing a wastegate using only compressed air to the inlet port will not yeild true results as there is no exhaust pressure on the valve.
Back pressure from the stock muffler is taken into account with the OEM wastegate spring and will not yield exact results when the exhaust system is altered. The spring used must accommodate the new (different) pressures created by the new exhaust system to remain identical in cracking pressure and full boost pressure.
There is no such thing as a "1.0bar" spring for every application. Close, yes, but not exact.
True Brian.
You have done alot of dyno testing and exhaust systems. Can you give a range of exhaust backpressures that we are likely to see in our turbo cars?
Say for a typical upgrade like a set of your headers and a k27S turbo with performance muffler what would the exhaust backpressure be in the manifold at the wastegate?
I am just interested in a ballpark number to see what kind of pressure we should expect. Not having instrumented my exhaust system I have always wondered what type of pressure the turbine housing sees and you might have this info.
How much would changing the performance muffler to a zork change this number as well if you have this data?

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 06-05-2013, 09:08 AM
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