I believe Helmholtz's ideas have been extended to create a resonator
that has a fairly wide peak, giving at least some improvement over about
a 3:2 range (like 4000 rpm to 6000 rpm). (At least one design has two
peaks offset from each other, giving a response curve with a dip in the
middle, like a bass reflex speaker.)
In any case, I've seen the Helmholtz name used elsewhere in reference to
motorcycle exhaust systems that apparently really do produce more
power. That doesn't mean Flowmaster is on the level, but they might be
<g>
Randall
"Michael D. Porter" wrote:
>
> Otherwise, I believe the Helmholtz resonator, as described above, has no
> real application for automotive use, and Flowmaster has simply adopted
> the term as a fancy, and misleading, means of describing a blanked
> expansion chamber in an otherwise standard muffler. Since the size of
> the chamber and the opening to the chamber are fixed, it will resonate
> only at a specific frequency, and as everyone knows, modern engines must
> operate at widely variable rpm, and the exhaust system of such engines
> is a compromise to accept highly variable gas speeds and exhaust gas
> sonic properties.
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