Hi Paul
I guess you are in the throes of returning from down under to up over.
I wish you a safe trip home.

I have a question you may have a chance to answer before leaving.
Knowing that the length of the inlet manifold tubes for a rotary
operating in the 6000 to 7500 rpm range for best performance requires
shorter tubes than for when operating in the automobile speed range
we are wondering what impact the length of the pipe between the
throttle body and a filter box would have in effecting the overall
length of the inlet tubes and hence the performance of the motor.

Should it be kept as short as possible or does it not matter?
What effect if any does the volume in the filter box have  in
dampening air flow wave formation in the inlet?
If any of your readers is aware of an off the shelf by
pass valve (3 way) suitable for the 80mm inlet we would
love to know about it.

Your thoughts on these issues will be appreciated.
Kind regards
Bob Izett.

Tuned pipe work like tuned electronic circuits. Put two tuned
pipes in series both tuned to 6000 RPM and the band at which
they work over will be reduced but the effectiveness will be increased.
Tune one for 5500 and another for 6500 and the band will be widened
but the effectiveness will be reduced.

You won't have enough room under the cowl to do this so
keep the pipe from the plenum to the air scoop as short as
possible to minimize the negative effects.

Here are some ideas for low profile tuned p-port intake manifolds.
They are all based on standard 3 inch radius 2 inch OD tube


Paul Lamar