Porsche 918 RSRJanuary 13, 2011
Porsche’s latest hybrid technology is on show in the Porsche 918 RSR at the North American Auto Show in Detroit.
The Porsche 918 RSR is a two-seat mid-engined coupé that is a combination of the hybrid technology in the 911 GT3 R race car and the design of the 918 Spyder concept.
The Porsche 918 RSR, a racing version of the 918 Spyder concept car, has the flywheel accumulator from the 911 GT3 R hybrid racing car, which generates additional power when braking.
The V8 engine is a further development of the direct injection engine from the successful RS Spyder race car, but for the 918 RSR it has been tuned to deliver an output of 563 hp at 10,300 rpm.
Electric motors on the two front wheels each contribute 75 kW (102 hp), i.e. a total of 150 kW (204 hp), to result in a total of 767 hp. This additional power, which is generated during braking, is stored in an optimised flywheel accumulator, which is positioned inside the car instead of a second seat.
This flywheel accumulator is an electric motor whose rotor rotates at up to 36,000 rpm to store rotation energy. Charging occurs when the two electric motors on the front axle reverse their function during braking processes and operate as generators.
At the push of a button, the driver is able to call up the energy stored in the charged flywheel accumulator and use it during acceleration or overtaking manoeuvres. The flywheel is braked electro-magnetically in this case in order to additionally supply up to 2 x 75 kW (totalling 150 kW) from its kinetic energy to the two electric motors on the front axle.
This additional power is available for around eight seconds when the system is fully charged. In the 911 GT3 R Hybrid, this additional power can also be used as a consumption aid depending on the racing situation, e.g. to delay pit stops or reduce the fuel tank volume and therefore the weight of the vehicle.
The two electric motors offer a torque vectoring function with variable torque distribution to the front axle. This increases agility and improves steering response.
Porsche describes the 918 RSR as an experimental racing laboratory.