Porsche 911 GT3 R Hybrid
From Porsche press: The innovative hybrid technology featured in the car has been developed especially for racing, standing out significantly in its configuration and components from conventional hybrid systems. In this case, electrical front axle drive with two electric motors developing 60 kW each supplements the 480-bhp four-litre flat-six at the rear of the 911 GT3 R Hybrid. A further significant point is that instead of the usual batteries in a hybrid road car, an electrical flywheel power generator fitted in the interior next to the driver delivers energy to the electric motors.
The flywheel generator itself is an electric motor with its rotor spinning at speeds of up to 40,000 rpm, storing energy mechanically as rotation energy. The flywheel generator is charged whenever the driver applies the brakes, with the two electric motors reversing their function on the front axle and acting themselves as generators. Then, whenever necessary, that is when accelerating out of a bend or when overtaking, the driver is able to call up extra energy from the charged flywheel generator, the flywheel being slowed down electromagnetically in the generator mode and thus supplying up to 120 kW to the two electric motors at the front from its kinetic energy. This additional power is available to the driver after each charge process for approximately 6 - 8 seconds.
Energy formerly converted – and thus wasted – into heat upon every application of the brakes, is now highly efficiently converted into additional drive power.
Depending on racing conditions, hybrid drive is used in this case not only for extra power, but also to save fuel. This again increases the efficiency and, accordingly, the performance of the 911 GT3 R Hybrid, for example by reducing the weight of the tank or making pitstops less frequent.