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TCI Auto Racing Calculators
Navigation of the TCI Racing Calculators page is easy! Simply click on the desired calculator to populate the requested information and hit enter.
1/4 Mile Horsepower (HP)
Enter the MPH and Weight for 1/4 Mile Horsepower, Then Press 'Enter' Key
HP = Weight * (MPH/234) ^ 3
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1/4 Mile ET & MPH By Weight & HP
Enter the Weight and HP for ET and MPH, Then Press 'Enter' Key
MPH = 234 * (HP / Weight) ^ .3333
ET = 1353 / MPH
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1/4 Mile ET to 1/4 Mile MPH Conversion
Enter ET for MPH or MPH for ET, Then Press 'Enter' Key
ET = 1353/MPH
MPH = 1353/ET
=1/4 Mile ET to 1/8 Mile ET Conversion
Enter the ¼ Mile ET or the 1/8 Mile ET and Press 'Enter' Key
¼ Mile ET = (1/8 Mile ET + .22) / .655
1/8 Mile ET = (¼ Mile ET * .655) - .22
=% Converter Slip Calculator
Enter the RPM, Tire Height in inches, The Rearend Gear Ratio, The Transmission Top Gear Ratio, and The MPH, Then Press 'Enter' Key
Conv Slip% = [((RPM * Tire Height) / (Rearend Ratio * Trans Ratio * MPH * 336)) -1] * 100
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1/4 Mile MPH Calculator by RPM, Tire Height, Rearend Ratio, Trans Ratio, & Converter Slip
Enter the Tire Height in Inches, The Rearend Ratio, RPM, Trans Ratio, & Converter Slip% , Then Press 'Enter' Key
MPH = (RPM * Tire Height) / (Rearend Ratio * 336.136 * Trans Ratio * (1 + (Conv Slip% / 100)))
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1/4 Mile RPM Calculator
Enter MPH, The Tire Height in Inches, The Rearend Ratio, Trans Ratio, & Converter Slip %
RPM = (Rearend Ratio * MPH * 336.136 * Trans Ratio * (1 + (Conv Slip% / 100))) / Tire Height
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Optimum Tire Height Based on MPH, RPM, Converter Slip & Rear Gear
Enter the Rearend Gear Ratio, the 1/4 Mile MPH, the RPM, the Transmission top gear ratio, Conv Slip%
Tire Height = (Rearend Ratio * MPH * 336.136 * Trans Ratio * (1 + (Conv Slip% / 100))) / RPM
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Optimum Rearend Ratio Calculator
Enter the Tire Height in Inches, The Rearend Ratio, RPM, Trans Ratio, & Converter Slip%
MPH = (RPM * Tire Height) / (Rearend Ratio * 336.136 * Trans Ratio * (1 + (Conv Slip% / 100)))
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Tire Height Based On Sidewall Designation
Enter the Tire Width in Millimeters, The Aspect Ratio, The Wheel Diameter in Inches, and Press 'Enter' Key
Tire Height(in) = (Width(mm) / 25.4 * Aspect Ratio / 100 * 2) + Wheel diameter
Tire Width(in) = Width(mm) / 25.4
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Tire Width (mm) and Aspect Ratio Based on Height and Width (in.)
Enter the Tire Height in Inches, The Tire Width in Inches, The Wheel Diameter in Inches, Then Press 'Enter' Key
Tire Width(mm) = Tire Width(in) * 25.4
Aspect Ratio = (Tire Height - Wheel Diameter) / 2 / Tire Width * 100
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Effective & Equivalent Gear Ratios Based On New and Old Tire Heights & Original Gear
Enter the New Tire Height, Old Tire Height, & Original Rear Gear Ratio, Then Press 'Enter' Key
Effective Ratio = (Old tire height / New tire height) * Original ratio
Equivalent Ratio = (New tire height / Old tire height) * Original ratio
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Engine Displacement
Enter the Bore in Inches, the Stroke in Inches, the Number of Cylinder, Then Press 'Enter' Key
Displacement = (Bore / 2) ^2 * PI * Stroke * # of Cylinders
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Carburetor Sizing for Normally Aspirated Engines (Normally Aspirated)
Enter Engine Size in Cubic Inches and the Maximum RPM, Then Press 'Enter' Key
Theoretical CFM = (Displacement * RPM) / 3456
Street Carb. CFM = ((Displacement * RPM) / 3456) * 0.85
Race Carb. CFM = ((Displacement * RPM) / 3456) * 1.1
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