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Old 03-31-2012, 02:30 AM   #54 (permalink)
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Originally Posted by abogart View Post
Instead, one would want to simply reduce the tailpipe diameter. OR, perhaps a flapper or check valve with a fixed spring pressure which could effectively allow only enough open area to permit exhaust to flow out at a set velocity over a broad range of engine speeds.

Just my thinking out loud here, I might be totally wrong.
Back in the old days I saw some cars with a butterfly valve in the collector of the exhaust manifold. It had a thermal spring so it would open when it was warmed up. This was on V engines and on one side only. It may have had been a way to warm up the engine sooner. This was before ERGs.
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