PRP Velocity Lessons

273 said

Pretty cool build, any idea the velocity (fps) they be running?
How much time in effort and $$$ to R&D those heads and combo to get 2.2hp per cfm ?

Click to expand...

If 1.91 sq inches is the average CSA, the calculation would be this:

(195 cfm)x(1m/60s)x(144ci/cf)x(1/1.91ci)=245ft/s velocity which is actually kind of low

145cc=8.848cubic inches so port centerline length would be (8.848ci/1.91si)=4.633 inches which is short for a SBM or SBC

My guess is the average CSA is actually lower than 1.91 which would raise the peak velocity and lengthen the centerline length.

Either way, that's a stout little engine.