Paul, I believe there has been some discussion about runner length, and
if using a plenum changes runner length? Here is a pic of the plenum that
I'll be using on the straight side its 4". I'm planning on using about
10" of this "D" extrusion and have my velocity stacks flush with the
interior of the 4" flat side. What should be total runner length from
the rotor housing face to the velocity stack for the P-Ported engine?

Thanks,
Rick in Alaska


The pic was not attached.

A distinct possibility if the plenum is too small. Helmholtz resonators
enter into the equations.

http://www.phys.unsw.edu.au/jw/Helmholtz.html
http://en.wikipedia.org/wiki/Helmholtz_resonator


I would make it larger volume if possible.

Total runner length is 19 to 21 inches tuned for peak torque
and best BSFC at 6000 RPM and max HP at 7500 RPM.

Paul Lamar