I'm a newbie here... Just ordered my Genboard & hoping to contribute to making new stuff.

I have written a street dyno before (for old shape Impreza WRX)

It was based on sampling RPM very quickly through the engine diagnostic port and time stamping the data...

I'll dig out the rest of the equations later - air drag and so-on.

Sensors that can be used

Vehicle speed - note that climb is also interesting, not just horizontal component

To deal with climb, I did 2 runs (one there and one back) and took an average. This also helps with wind.

I have found that GPS altitude is not all that accurate as it seems a lot of handhelds use pressure to work out altitude (even if they claim to do it using the satalites!)

RPM-only dyno: problems

The main problem was the quantization in RPM - this limited useful data points and made the answer very "noisy" at times. (Road speed has worse quantization in these cars!!)

Other problems were accounting for clutch slip and wheelspin. (Not too bad to do)

It is also possible to measure free-revving, which eliminates vehicle-speed measurements altogether. However,