Dynamometer GuideThere are 2 basic types of chassis dyno. One type is the inertia dyno. The inertia dyno measures the speed of a an object, spun by the wheels of a vehicle, to come up with horsepower and torque numbers.
The other type is the hydraulic dyno, which measures the horsepower and torque of a vehicle by applying varied levels of resistance to the drive line. Both dynamometer types have their advantages and disadvantages.