Formula Page

Formulas for mph, rpm, tire diameter, and rear gear ratio:
mph =  rpm x tire diameter (inches) gear ratio x 336 rpm =  mph x gear ratio x 336 tire diameter (inches) tire diameter =  mph x gear ratio x 336 rpm gear ratio =  rpm x tire diameter (inches) mph x 336		mph rpm tire diameter gear ratio Enter three values and select 'Calculate'.
Formula to calculate tire diameter from tire size data:
tire diameter =  section width x aspect ratio 1270 + rim diameter Where:  Width is the first number in the tire size, in millimeters.  Aspect ratio is the second number,   as a ratio of side wall height to tread width x 100.  And rim diameter is the diameter of the rim in inches. Therefore a tire marked 195/50ZR15 has the following properties: Width = 195 mm     Aspect Ratio = 50%     Rim Diameter = 15 in tire diameter =  195 x 50 1270 + 15 = 22.67"		section width aspect ratio rim diameter Enter above values and select 'Calculate'. tire diameter =
Formula to calculate a 1/4 mile ET from vehicle weight and engine horsepower:
ET = ((vehicle weight/engine hp) ^ .333) x 5.825		vehicle weight (pounds) engine horsepower Enter above values and select 'Calculate'. 1/4 mile ET =
Formula to calculate carburetor size:
cfm = ((rpm x displacement) / 3456) x ve cfm = 'cubic feet per minute' of air flow through the carburetor rpm = maximum engine speed displacement = engine size in cubic inches ve = volumetric efficiency, 85% typical, higher for more performance engines		rpm displacement ve (%) Enter above values and select 'Calculate'. cfm =
Formula to calculate engine displacement:
displacement = radius² x Pi x stroke x number of cylinders displacement = cubic inch volume displacement of piston movement in an engine radius = radius of cylinder bore in inches bore = diameter of cylinder in inches Pi = a constant, 3.14159 stroke = distance in inches that a piston moves number of cylinders = duh		radius OR bore stroke no. of cylinders Enter above values and select 'Calculate'. displacement = cubic inches