1/4 Mile Calculator

 
Drag Racing Calculators  - Horsepower calculations are rated at the crankshaft.

 

1/4 Mile HP 1/4 ET & MPH based on weight and HP 1/4 ET <> MPH 1/4 ET<> 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    

 

 

 

 

 

 

1/4 Mile Horsepower Calculator
       
MPH Weight       HP
     
Enter the MPH and Weight and
Click on Calculate...
HP = Weight * (MPH / 234) ^3





 

1/4 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





 

1/4 Mile ET & MPH Calculator #2
   
ET     MPH
   
Enter the ET or MPH and
Click on Calculate...
ET = 1353 / MPH
MPH = 1353 / ET





 

1/4 Mile ET & 1/8 Mile ET Conversions
   
1/4 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





 

1/4 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%)





 

1/4 Mile RPM Calculator
         
Tire Height Rearend Ratio MPH Trans Ratio Conv Slip%   RPM
 
Enter the Tire Height in inches,
The Rearend Gear Ratio, the 1/4 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 1/4 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
(in3)
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

 

 

 

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