[wparsons]

Originally Posted by Spuds

And I'll repeat my question. What is the actual weight (well, mass really) of your car at the time of the run, and how much fuel was in it? I'm pretty sure virtual dyno follows an equivalent energy strategy to calculate output. For that you need an absolutely accurate mass.

A heavier vehicle takes more energy to accelerate to a given speed as a lighter vehicle. If that acceleration is over the same period of time, the heavier vehicle will have had greater power applied. Virtual dyno probably starts with the acceleration numbers and back calculates the amount of energy that must have been put into the vehicle using the kinetic energy model. If your mass is off, your power output calculations are off.

Plus it assumes a 100% perfectly flat road with no wind. To rule out slope or wind you'd have to do pulls in both directions and average out the graphs.