Paul Yaw wrote:

Paul wrote:

Jeff Spitzer wrote:

Two points.

1) The actual propagation of waves is more complex than simple
speed of sound.  For instance, the speed of sound is superimposed on the
flow in the pipe.  For long pipes this is not trivial.  Don't get me wrong,
the simple calculations presented previously are a great way for a first
guess.

2)  The physical process described by Paul Yaw is correct and
accounts for different tuning effects with pipe diameter.  The general rule
is smaller pipes will give more power (yes more) at the tuned condition but
less at detuned conditions (which is everywhere else).  So if you truly
want a peaky system keep the pipes small (up to the point where frictional
losses get extreme)  If you want a flatter torque curve then keep the pipes
bigger.

Jeff Spitzer

For what it's worth, I am in agreement.  Pressure wave tuning does not
follow simple speed of sound calculations all that closely.  For the
sake of our conversations it seemed most appropriate to not muddy the
waters any further.  The fact is that "perfect" tuned lengths can only
be arrived at experimentally.  Applying speed of sound calculations to
the exhaust system will show even greater errors because of the extreme
temperature and pressure variations.

Paul Yaw

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