Z31 Speed and RPM Calculator
This calculator was written by Paul Hillman (AZ-ZBUM) back in the day. Credit goes to him for the calculations.
Calculator Form
This will calculate the actual speed or RPM given the other. Change any of the settings below to see the effects.
| Gear | Gear ratio | Speed (MPH) at 6000 RPM | RPM at 75 MPH |
|---|---|---|---|
| 1st | 3.350 | 36 | 12570 |
| 2nd | 2.056 | 58 | 7714 |
| 3rd | 1.376 | 87 | 5163 |
| 4th | 1.000 | 120 | 3752 |
| 5th | 0.752 | 159 | 2822 |
| Rev | 3.153 | 38 | 11830 |
Formula Used
Tire Width (mm) x Aspect Ratio
Tire Height (inches) = Wheel Diameter (inches) + 2 x ------------------------------
2540
Rollout (inches) = Tire Height x PI
Engine RPM x Rollout
Speed (MPH) = -----------------------------------------
1056 x Diff Gear Ratio x Trans Gear Ratio
1056 x Speed (MPH) x Diff Gear Ratio x Trans Gear Ratio
Engine RPM = -------------------------------------------------------
Rollout
Sources Used
- Written by Paul Hillman (AZ-ZBUM)