Can anyone explain me what kind of chassis dynos are used to measure shaft torque/power and how they do it. BTW... Things I allready known; I know that inertia brake dynos use a solid disc flywheel of a constant mass and radius and by meassuring time and flwheel speed (rpm), we can calculate flywheel kinetic energy and power and with car's wheel size, and drivetrain ratio we can calculate torque. I also known that we can calculate drivetrain and tyre losses by coasting down method(disengaged clutch), but all power/torque readings measured like that won't be accurate as we can't know car's rotational parts inertia (wheels and gears). So does chassis dynos use some extra el motor to measure frictional loses and thus calculate car's rotational inertia?