Quote:
Originally Posted by Rattmann
There will not be enough back pressure to optimize the turbo to gain momentum to be able to propel the Kompressor side of the air in take.
Basically you will introduce a "turbo LAG".
As we all know that it is not a Conversional turbo, but uses dual mass/size turbine in a single axil to the Kompressor on 35i.
Please check if 50i has this setup or not, technically it should NOT since there are two separate turbo for each bank of the V8.
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First, the wastegate controls back pressure, so you can run an open pipe and it won't matter - back pressure is a bad thing on a turbo engine and the flapper in no way is there to control back pressure. First performance mod on a turbo is typically to open up the downpipes and exhaust system to increase flow and reduce back pressure.
Second, having 2 turbos for each bank of cylinders has nothing to do with having this valve or not, the N54 has 2 separate turbos and 2 complete exhaust pipes all the way to the back to 2 mufflers, but as on the 5.0i, the mufflers are both connected and the entire design of that flapper valve is to control noise at lower rpm's when you don't need all the exhaust flow the system is capable of, then it opens up when you need the flow and you are above the EPA rpm level for noise measuring.
The whole point of this mod is to allow the exhaust to make a little more noise at idle and at low RPM's, nothing more, won't help or hinder performance.
FYI - this valve is only used in markets where noise levels are an issue, not all markets have the flapper valve - same is true if you buy the BMW performance exhaust, US has the flapper valve, most of Europe comes without it.