Pulley Ratio Calculator: ((14.7+ Boost in psi)/14.7) X (engine liters/2)/supercharger in liters)=Pulley Ratio at sea level
Pulley ratio formula for a crank driven supercharger: (crank pulley size /supercharger pulley size)= pulley ratio
Blower sizes:
- M45/MP45: 0.737L
- M62/MP62: 1.016L
- M90/MP90: 1.474L
- M112/MP112: 1.835L
- M122/MP122: 1.999L
- TVS900 0.9L
- TVS1320: 1.32L
- TVS1540: 1.54L
- TVS1900: 1.9L
- TVS2300: 2.3L
- TVS2550: 2.65L
General information that has been published by Jim Bell:
1 psi boost requires 1.5 octane (minimum) 1 psi boost = .5 point CR (effective CR)
1 AF ratio = 2 octane (example 12.5:1 to 11.5:1)
1° advance = 1/2 – 3/4 octane point
20° ambient = 1 octane
10° engine coolant (160° -180° range) = 1 octane
1000′ altitude = .5 psi (2″ Hg)