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MOTORSPORT TOOLKIT

Below you will find a range of 'popup' calculator tools for Power,
Gearing, Torque/Power/RPM and Wheel parameter preparation.

If there are any other tools you would like us to include or you have
suggestions regarding the existing set then we would be pleased to
hear from you.

Also, you may find this useful - click here for a list of kit car manufacturers !
                                                                                               ED.

Horsepower & Aerodynamic Drag Calculator

Use this tool to find the approximate horsepower required to obtain a target maximum speed
[V max]. The majority of the drag imposed upon on a vehicle is aerodynamic drag rather than rolling resistance from bearings, tires and curb weight factors.
 
Click here to open Horsepower & Aerodynamic Drag Calculator.

Fixed parameters: Road surface is concrete, tire pressure 32 psi all round and temperature is approx. 20 degrees.

Gear Ratio Calculator

This tool will calculate theoretical speed for a vehicle in each of its gear ratios. Enter the tyre diameter in mm, maximum permissible RPM, differential ratio and the gear ratios that apply where, for example, there no need to enter anything in '6th' gear for a car with only 5 gears.

To obtain the dynamic tire diameter there are 3 possibilities.

Method 1:
To obtain the dynamic rolling diameter in mm we recommend using our Wheel Calculator below which accounts more accurately for the tyre profile, load and dynamic conditions.

Method 2:
Use a tape and level on the one of the drive wheels and record the diameter result from the ground to the highest point on the tyre and then add 3.5% or multiply by 1.035 for the dynamic running diameter (as the tyre is crushed more when static and expands due to centrifugal force when spinning).

Method 3:
Add the wheel diameter to twice the height of the tire sidewall. For example, a car with 205/50 tires has a sidewall height of 4.035" (205 mm x 50/100 is 102.5 mm which is 4.035"). If it has 18" wheels then the tire diameter is approx. 26.1" (18 + 4.035 + 4.035) then multiply by 25.4 to convert to mm. Finally subtract 3% or multiply by 0.97 for the dynamic running diameter (as the tyre diameter is reduced under the load of the vehicle).
 
Click here to open the Gear Ratio Calculator.

Note: Maximum speed [V max] is limited either by gearing or by aerodynamic drag.

Fixed parameters: None

Horsepower, Torque and RPM Conversion Calculator

Use this tool to convert 3-ways: (1) Horsepower + RPM into Torque (2) Torque + RPM into Power and (3) Horsepower + Torque into RPM.
 
Click here to open Horsepower, Torque and RPM Conversion Calculator.

Fixed parameters: None

Wheel & Tyre Combination Calculator

Use this tool to find the approximate values for fitted size and volume. We have included a 'Dynamic Rolling Diameter' figure to allow this to be used within the Gear Ratio Calculator above.
 
Click here to open the Wheel Calculator.

Fixed parameters: Tyre pressure 32 psi

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