Quote:
Originally Posted by Paul Workman
OK, I got a clear picture now.
Your approach is interesting, and I suspect has very "digital" (read: either ON or OFF!) characteristic, compared to the direct vacuum line from the plenum to the NPPs (i.e, the FBI approach).
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Believe me, I would have liked to have just run from plenum vacuum, (I tried it), but there is rarely a flat stretch of road where I live and the uphill sections raise the engine load and cause the manifold vacuum to drop down enough to let the flapper start to crack open. It doesn't have to open very far before the resonance starts in.
My way requires both a (programmable) minimum rpm and throttle position condition. Surprisingly, it isn't as 'digital' as I would like it since my vacuum hose diameter being restrictive, causes a pretty slow opening and closing. As time permits I will run a second line and fiddle with the vacuum switch setting. I might even tweak the secondary activation curve in the lower revs near the resonance point around 1800-2000 rpm.
It was a fun modification, especially since I have an aversion to all the extra attention loud pipes get you.