Miscellaneous Formulae

Contributed By: Joe Schaefer

Displacement/cu.in/mm

Cubic inches:

        cu.in = 0.7853982 x bore squared x stroke x numzber of cylinders

For metric(mm) use conversion factor of: 2.54 for bore and stroke.

        mm = 0.785 x (bore squared x 2.54) x (stroke x 2.54) x # of cyl

HP/Torque

        hp = rpm x torque
                     5252

        torque = 5252 x hp
                             hp

Horsepower loss at altitude:
        Note: elevation in feet.

        hp loss = elevation x 0.03 x hp @ sea level
                                            1000

Air Flow

Air capacity:

        cfm = rpm x displacement
                            3456

Volumetric Efficiency:

        VE in % = airflow cfm x 100
                             rated cfm