| Automotive Math PAGE ONE |
| Engine Related Formulas How To Calculate CFM: Engine size (CID) x maximum RPM / 3456 = CFM CFM @ 100% volumetric efficiency Cylinder volume (displacement) =3.1416 x bore x bore x stroke Compression ratio = Vi � V2 (Where Vi is total volume of one cylinder and V2 is volume of space above piston at top of stroke) Brake Horsepower (BHP) = RPM x torque (in lbs ft.) = 5252 (Note:) Formula is actually 6.28 x RPM x torque by dividing 6.28 into 33,000 we get 5250Piston speed (ft. per mm.) = 2 x RPM x stroke in feet) 1 mile per hour = 1.467 feet per second Engine displacement = Cylinder volume times number of cylinders Piston speed (ft. per mm.) = 2 x RPM x stroke in feet Torque = BMEP x Swept volume (in cc) 2473 MPH (RPM x wheel diameter in inches) = gear ratio x 336 (Note: Wheel diameter is overall diameter of the inflated tire, not the nominal diameter of the wheel.) |