No idea of the length of intake runners. Bill C. on the list (SEMIHEMI01)
suggested some kind of big ABS penny-whistle as part of the intake. I pictured
it driven by vacuum or motor that would always keep that growl at all RPMs
rather than just 2200. That would give you the resonance, getting the standing
wave at the right phase would be the next part. Time for fuzzy logic to step
in. A feedback loop involving pressure diffs (amplitude) and phase of column
of intake charge or something like that. EPC. Electronic penny-whistle
control.
Bruce Bridges wrote:
> Marty,
> Yes! The engine will pull the intake tract through many "different"
> frequencies. Its the one @ 2200 rpm that sets up a standing wave in the
> intake tract and starts howling that you would want to eliminate! Much like
> the whistling FIPK syndrome! My thought was that the intake tract must
> "play" with the resonant cavity tuning of the intake manifold, but cant be
> obnoxious under the normal RPM range. As a "constrained" factory designer
> with a lot of conflicting priorities Id be skeered to put a "Tune" to the
> intake tract for anything but noise reduction, knowing that the final cut by
> the QA group will be made on sound, not actual performance...Wimps...Any Ide
> how long the intake runners on the 4.7 are? I need to get under the hood of
> one soon...
> Bruce
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:56:10 EDT