Impeller speed
Example : 7.25 x 3.7 = 1.959 x 4.10 (p1sc-1 step-up) = 8.03 x 6500 rpm = 52,219 impeller speed
Example : 7.25 x 3.7 = 1.959 x 4.10 (p1sc-1 step-up) = 8.03 x 6500 rpm = 52,219 impeller speed

I usually do it this way which makes it easier to change the value of the SC pulley to figure out what you exactly need.
(Crank Pulley*max RPM*Step up ratio)/ SC pulley
(7.25*6500*4.10)/3.70= 52,219 impeller speed.


