The car is strapped down so it cannot move laterally or longitudinally, with non-driving wheels choked on 2 wheel drive dynamometers.

On a 4 wheel drive chassis dyno, the distance between the front and the rear sets of rollers can be changed to cater for dynotuning different wheel-based cars.

Front-wheel-drive cars tend to be more unstable on dynas than RWD cars, so when dynotuning FWD cars, small "trainer wheels" are locked into place either side of the front wheels.

A large fan is placed at the front of the car to cool the radiator and any other heat exchangers located there.

The dyna tuner sits in the driver's seat and operates the accelerator, clutch and brake.

The steering wheel does not need to be touched.

The dyno tuner controls speed and other factors via a hand-held pendant that contains controls for load.

The simplest test is a power pull.

The 'ramp speed' (rate at which the dynamometer lets the engine speed increase) is set and the car is run at very low rpm in the selected gear.

Any gear can be used, but second, third or fourth gears are usually selected.

The higher the gear the lower the tractive effort trying to pull the car of the dyno.

Very powerful cars therefore sometimes tested in the higher gears, although second gear is most commonly used.

The tuner instructs the dyno as to the type of test being undertaken holds the low rpm in the selected gear and then gives the engine maximum throttle.

Flicking a switch allows the dyno to ramp up in speed.

As the engine rpm increases, the dynas software draws a trace on a PC screen, showing the power being developed.

When the engine redline is reached, the test may be completed, or a switch on the controller may be flicked, causing the dyno to then ramp the engine back down.

Averaging ramp-up and ramp-down power pulls removes from the reading the inertia of the dynamometers rollers.