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Re: Tuning (was Old air filters for R1100S needed)

"Tuning" in the acoustic sense, as Brian correctly uses the term, is when
you have a resonance which produces some useful effect (either pushes extra
mixture into the cylinders or helps extract more after combustion). As he
says, engineers use these effects typically to fill a "hole" in performance
or to add oomph somewhere in the rpm compass. Most typically, to boost the
advertized HP at peak - which tends to be useless (or worse) for street

Sounds like a free-lunch engineering fallacy? You're right.

For every resonance boost, there is a cut at submultiples and multiples, as
far as I understand these things. So, to tune in some boost at 7400 rpm, you
have to accept some cut at 3700 rpm. Anybody want that?

In general, trying to tune (in this sense of the word) for any modifier
person like me is unsound. Very hard to predict ahead of time from theory
exactly where the boost will be (and no fun pasting an extra half-inch to
your exhaust manifold if your don't have it right on the first guess). Only
novice engineers believe you can predict stuff like that. And hard to guess
if you will want it in the same rpm spot next year, how to keep the resonant
point from wandering about with changing circumstances, and the funny and
unanticipated feel of artifical boost in your power curve.

As with loudspeaker bass, tuning for boost is has more drawbacks than
benefits, even if it feels like a free lunch.



End of oilheads-digest V2 #56