Dyno
Dyno is another term for a dynamometer. A dyno or dynamometer is used to measure torque, which in turn is used to determine the horsepower of an engine.
The two main types of dynos are engine dynamometers and chassis dynamometers. Engine dynos measure an engine's torque directly from an engine's crankshaft or flywheel. They are widely used by automobile manufacturers and engine rebuilders because they can test an engine without having to installing it in a car. Chassis dynos, in contrast, measure torque at the wheels by running them on rollers or occasionally by attaching directly to the wheel hub.
Horsepower measured by chassis dynos may be about 15 to 20 percent lower than if it were measured by an engine dynos. This is due to the loss of torque from friction in drivetrain elements such as the gearbox or transmission. As a result, measurements provided by an engine dyno are typically more accurate than those from a chassis dyno.