A dynamometer, or 'dyno', is a device used to measure engine output.
There are two main types of dynamometer used in automotive testing. An engine dynamometer, often called a test bed, directly measures the output of an engine at its flywheel.
The other type is a chassis dynamometer or rolling road dynamometer (above), which measures the output at the road wheels. Some types of chassis dyno can also measure drivetrain losses, and from this data an estimate of flywheel power can be made.
