Below is a list of Engine Dynamometer manufacturers from San Rafael, California. Engine dynamometers, or engine dynos, measure torque or revolutions per minute (RPMs) directly from an engine's crankshaft or flywheel. This data gives information about the engine's horsepower. Because engine dynamometers can be used to test engines separately from vehicles, they are widely used by automobile manufacturers, engine rebuilders and producers of high-performance vehicles such as race cars.