Welcome to the JMR-Racing Calculation Page

(These are just estimates based on simple calculations!)




Understanding Shift Points (RPM drop at shift) (Shifting at the proper time and the convertor will help reduce the loss)
1st Gear 2nd Gear 3rd Gear 4th Gear Rear Gear Tire Size Shift RPM
            1st to 2nd         2nd to 3rd         3rd to 4th
MPH MPH MPH
RPM RPM RPM
   

Engine Displacment (bore / 2) x PI x Stroke x # of Cylinders)
Displacment  Bore  Stroke  # of Cylinders
   

Amount of AIR engine can draw at Redline RPM (CID x Redline RPM / 3456)
CFM's  Cubic Inch  Red Line RPM
   

Carburetor Size Calculator (CID x Redline RPM / 3456) x VE  (Street Carb 0.85, Race Carb 1.10)
CFM's  Cubic Inch  Red Line RPM  Volumetric Efficiency  (0.85 - 1.10)
   

Roller rocker formula for actual cam lift (Cam Lift / Roller Rocker) x New Roller Rocker
Actual Lift  Cam Lift  Old Rocker  New Rocker
   

Minimum horsepower required to reach a 1/4 mile speed
HP formula
hp mph wgt
   

Estimated HP from 1/4 Mile ET and Weight
HP formula 2
hp ET wgt
   

Estimated HP from 1/8 Mile ET and Weight
HP formula 3
hp ET wgt