by Dr. Radut

Racing Calculator

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
(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

Typical Transmission Ratios

Transmission 1st 2nd 3rd 4th 5th 6th Rev
Corvette 3sp 2.21 1.32 1.00 2.51
Muncie Wide 4sp pre-’74 2.52 1.88 1.46 1.00 2.59
Muncie Close 4sp pre-’74 2.20 1.64 1.28 1.00 2.27
Borg Warner T-10 Wide 4sp early 2.56 1.91 1.48 1.00 2.64
Borg Warner T-10 Close 4sp early 2.20 1.66 1.31 1.00 2.26
Borg Warner Wide 4sp ’74 up 2.64 1.75 1.34 1.00 2.55
Borg Warner Close 4sp ’74 up 2.43 1.61 1.23 1.00 2.35
ZF 6 speed (Corvette) 2.64 1.78 1.30 1.00 0.74 0.49
Powerglide 1.82 1.00 1.82 R
Turbo 350 2.52 1.52 1.00 1.94 R
Turbo 400 2.48 1.48 1.00 2.08 R
700R4 3.06 1.63 1.00 .70 2.29 R
Richmond OverDrive 6 sp 3.27 2.13 1.57 1.23 1.00 0.76