Today I'm teaching you how to get your car's power curve WITHOUT using a dyno!
(Thanks to vehicle dynamics 😎)

1) Engage a given gear, then accelerate from low up to high rpm.
2) Acquire your car's speed (v) and rpm via an OBD sensor.
3) Compute the longitudinal acceleration ax as the derivative of speed (its rate of change).
4) Compute the tractive force F as mass × ax (drag can be neglected in lower gears).
5) Compute the engine Torque via the known tyre radius, gear ratio, and assuming a transmission efficiency (FWD/RWD: 0.85, 4WD: 0.75).
6) Power = Torque × rpm → plot both against rpm and you have your curves! ✅

Below are results from a diesel car I was testing: after the tune (red), peak torque rose by ~22 Nm above 2000 rpm, with a corresponding +15 hp peak power gain!

I really cannot help tinkering with this stuff...

Visualisations made via @JMP_software