Racing Calculators
Note:
These calculators work best with Microsoft Internet Explorer 4.0 or higher or Mozilla Firefox.
1/4 Mile HP
1/4 ET & MPH
based on weight and HP
1/4 ET
Û
MPH
1/4 ET
Û
1/8 ET
1/4 Mile MPH
based on tire, converter slip, gear & RPM
1/4 Mile RPM
based on tire, converter slip, MPH & rear gear
% Converter Slip
based on 1/4 Mile MPH, tire & gear
Optimum tire height
based on MPH, RPM, converter slip & rear gear
Tire Height
based on sidewall designation
Tire Width (mm) and Aspect Ratio
based on height and width (in.)
Optimum rear gear
based on tire, converter slip, MPH & RPM
Effective & Equivalent Gear Ratios
based on New and Old tire heights and original gear
Engine Displacement
Carburetor Sizing
for Normally Aspirated Engines
¼ Mile Horsepower Calculator
MPH
Weight
HP
Enter the MPH and Weight and
Click on Calculate.
..
HP = Weight * (MPH / 234) ^3
¼ Mile ET & MPH Calculator #1
Weight
HP
ET
MPH
Enter the Weight and HP and
Click on Calculate twice...
MPH = 234 * (HP / Weight) ^ .3333
ET = 1353 / MPH
¼ Mile ET & MPH Calculator #2
ET
MPH
Enter the ET or MPH and
Click on Calculate...
ET = 1353 / MPH
MPH = 1353 / ET
¼ Mile ET & 1/8 Mile ET Conversions
¼ Mile ET
1/8 Mile ET
Enter the ¼ Mile ET or the 1/8 Mile ET and
Click on Calculate..
.
¼ Mile ET = (1/8 Mile ET + .22) / .655
1/8 Mile ET = (¼ Mile ET * .655) - .22
% Converter Slip Calculator
RPM
Tire Height
Rearend Ratio
Trans Ratio
MPH
Conv Slip%
Enter the RPM, Tire Height in inches,
The Rearend Gear Ratio, the MPH,
the Transmission top gear ratio and
Click on Calculate..
.
Conv Slip% = [((RPM * Tire Height) / (Rearend Ratio * Trans Ratio * MPH * 336)) -1] * 100
¼ Mile MPH Calculator
Tire Height
Rearend Ratio
RPM
Trans Ratio
Conv Slip%
MPH
Enter the Tire Height in inches,
The Rearend Gear Ratio, the RPM,
the Transmission top gear ratio,
Conv Slip% and
Click on Calculate..
.
MPH = (RPM * Tire Height) / (Rearend Ratio * 336.136 * Trans Ratio * Conv Slip%)
Optimum Rearend Ratio Calculator
Tire Height
MPH
RPM
Trans Ratio
Conv Slip%
Rearend Ratio
Enter the Tire Height in inches,
The ¼ Mile MPH, the RPM,
the Transmission top gear ratio
Conv Slip% and
Click on Calculate...
Rearend Ratio = (RPM * Tire Height) / MPH * 336.136 * Trans Ratio * Conv Slip%)
¼ Mile RPM Calculator
Tire Height
Rearend Ratio
MPH
Trans Ratio
Conv Slip%
RPM
Enter the Tire Height in inches,
The Rearend Gear Ratio, the ¼ Mile MPH,
the Transmission top gear ratio
Conv Slip% and
Click on Calculate...
RPM = (Rearend Ratio * MPH * 336.136 * Trans Ratio * Conv Slip%) / Tire Height
Optimum Tire Height Calculator
Rearend Ratio
MPH
RPM
Trans Ratio
Conv Slip%
Tire Height
Enter the Rearend Gear Ratio, the ¼ Mile MPH,
the RPM, the Transmission top gear ratio,
Conv Slip% and
Click on Calculate...
Tire Height = (Rearend Ratio * MPH * 336.136 * Trans Ratio * Conv Slip%) / RPM
Engine Displacement Calculator
Bore
Stroke
# of Cylinders
Displacement
Enter the Bore in inches, the stroke in inches,
the number of cylinders, and
Click on Calculate..
.
Displacement = (Bore / 2) ^2 * PI * Stroke * # of cylinders
Tire Height & Width Calculator
Tire Width
(mm)
Aspect Ratio
(1-100)
Wheel Diameter
(in)
Tire Height
(in)
Tire Width
(in)
Enter the tire width in millimeters, the aspect ratio,
the wheel diameter in inches, and
Click on Calculate..
.
Tire Height(in) = (Width(mm) / 25.4 * Aspect Ratio / 100 * 2) + Wheel diameter
Tire Width(in) = Width(mm) / 25.4
Tire Width & Aspect Ratio Calculator
Tire Height
(in)
Tire Width
(in)
Wheel Diameter
(in)
Tire Width
(mm)
Aspect Ratio
(1-100)
Enter the tire height in inches, the tire width in inches,
the wheel diameter in inches, and
Click on Calculate...
Tire Width(mm) = Tire Width(in) * 25.4
Aspect Ratio = (Tire Height - Wheel Diameter) / 2 / Tire Width * 100
Effective & Equivalent Gear Ratio Calculator
New Tire Height
Old Tire Height
Original Ratio
Effective Ratio
Equivalent Ratio
Enter the New tire height, Old tire height,
and the original rear gear ratio.
Click on Calculate..
.
Effective Ratio = (Old tire height / New tire height) * Original ratio
Equivalent Ratio = (New tire height / Old tire height) * Original ratio
Engine Air Capacity & Carburetor Size Calculator
(normally aspirated)
Displacement
(in
3
)
Max. RPM
Theoretical Capacity
CFM
Street Carb.
Size CFM
Racing Carb.
Size CFM
Enter the engine size and maximum RPM
Click on Calculate..
.
Theoretical CFM = (Displacement * RPM) / 3456
Street Carb. CFM = ((Displacement * RPM) / 3456) * 0.85
Race Carb. CFM = ((Displacement * RPM) / 3456) * 1.1