Originally Posted by exdos
Acceleration can be calculated from the recorded figures of RPM and the time stamp data, plus the wheel diameter and gear ratio in the vehicle profile and Pi as the constant.
This is simply calculating vehicle speed based on RPM and gear ratio figures and then calculating average acceleration. I am assuming you are doing a basic delta v/delta t calculation. That would not yield instantaneous acceleration, and would be somewhat inaccurate, but I guess it depends on how close your time points are exactly. Plus, why not simply use the vehicle velocity data from the OBDII? Is it not as accurate?