In order to know the power that dissipates the common brakes of the cars we can make some estimations: 

When a car brakes strongly from maximum speed to zero, the brake has to absorb about three times the power of the car engine. We could consider the power of the brakes around 250 hp. nevertheless the brakes warm up quickly and they lost effectiveness in a half minute.

we can say that:

• We can absorb great amount of power during just a short time, sufficient to make a test.
• We can absorb little power of continuous form, the power are limited approximately to 15 hp (according to brake) in continuous tests.

The brake is driven by electrovalve that is controlled by the electronic module, the pneumatic pressure is provided by a regulator where a constant pressure is selected, the torque of braking is linear with the pressure, the optimal pressure experimentally obtains so that the test lasts approximately 10 seconds, for each engine we will always use the same pressure.

The more accurate way to work with this dynamometer consists of raising the motor the maximum regime and applying the brake until stopping it (automatic actuation). The curve appears in screen from RPM max to engine stop.