How does the dyno measure power?

The Dyno Dynamics Chassis Dyno uses a very accurate load cell to determine the force applied to the dyno roller by the vehicle. This value can be output as “Tractive Effort”, and is used to calculate the vehicles horsepower with repeatable results(ie testing the same car on a different dyno dynamics machine should give you the same results whether it be here, Australia, the States or even the north pole) . This is a far more precise way to calculate power than by calculating horsepower based on the roller speed rate of change or by hydraulics where the viscosity can change with heat like other dynos do.