pulley/rpm/math question

[JusDreaming]

I have a pump with a 7" pulley, a drive pulley on the engine is 4.5". WHat rpm do I need to run the engine to achieve 1450 rpm on the pump?

[svHyLyte]

The ratio of the circumference/diameters of the pully's is about 1.56 (or .64 depending upon which direction one chooses). Accordingly, for every revolution of the larger pully, the smaller pully will make 1.56 revolutions. Accordingly, to achieve 1450 RPM in the larger pully, the smaller pully will have to make 1.56 x 1450 = 2,256 RPM.

Cheers,

s/v HyLyte