Porsche continues to extend its high efficiency competence via intensive development work in the field of hybrid technology. The company is presenting a world premiere of a synthesis of 2010's successful hybrid concepts at the North American Auto Show in Detroit; the Porsche 918 RSR.
The 918 RSR is a two-seat mid-engined coupé that demonstrates what happens when the technology fitted in the 911 GT3 R Hybrid racecar and the design of the 918 Spyder concept are combined to create a modern, innovative super-sportscar.
With its highly-efficient flywheel accumulator, the 911 GT3 R hybrid racing car attracted attention during competitive racing on the Nürburgring Nordschleife circuit, the American Le Mans Series races (ALMS) at Road Atlanta, USA and the Intercontinental Le Mans Cup at Zhuhai in China.
Around these different circuits, the 911 GT3 R Hybrid – referred to internally as the ‘Race Lab’ – not only demonstrated its massive performance potential under motor racing conditions against top competitors, but actually surpassed the expectations of Porsche Motorsport.
Competitiveness, reliability and fuel efficiency combined with high performance underscored the technicians' basic idea of generating additional power in an intelligent manner. The 911 GT3 R Hybrid obtains its additional power from its own vehicle dynamics when braking. And now, Porsche is transplanting this technology into the mid-engined coupé 918 RSR, the motorsport version of the 918 Spyder concept car.
From the tradition established by classic Porsche long-distance racecars such as the 908 long-tail coupé (1969) and the 917 short-tail coupé (1971), the Porsche designers created a link to the post-modernism of the ‘form follows function’ philosophy. In the 918 RSR, the elegant lines are dominated by muscular wheel arches, dynamic air intakes and a pulpit-like cockpit.
A visible fan wheel between the ram air intake tubes, and a rear spoiler (with identical dimensions to that fitted on the RS Spyder racecar) additionally emphasize the racing laboratory function. The new ‘liquid metal chrome blue’ paint, was created emphasize the sculptured curves, while the typical Porsche hybrid orange on the brake calipers and longitudinal stripes along the body lend contrasting touches.
Motor racing technology also dominates within the light, stiff carbon fiber-reinforced plastic (CFRP) monocoque. The V8 engine is a further development of the direct-injection unit from the successful RS Spyder racecar, but for the 918 RSR it has been tuned to deliver an output of precisely 563hp at 10300rpm.
The electric motors on the two front wheels contribute 102 hp each, or a total of 204hp, to the peak drive power of exactly 767hp. This additional power, which is generated during braking, is stored in a flywheel accumulator.
In the 918 RSR, the two electric motors offer a torque vectoring function with variable torque distribution to the front axle. This additionally increases agility and improves steering response. Mounted ahead of the rear axle, the mid-engine is integrated with a racing transmission that is also based on that from the RS Spyder racecar. This six-speed constant-mesh transmission with longitudinally-mounted shafts and straight-toothed spur gears is operated using two shift paddles.
The car's functional equipment underscores its pure-bred motor racing character. Whether it is the characteristic doors; the air intake in the roof; the quick-action latches on the front and rear CFRP lids; the two roof-mounted antennas for pit radio and telemetry; the small, lateral front aerodynamic fins similar to those on the RS Spyder; the air splitters beneath the front lip; or the racing slicks on 19" wheels with center-locking nut, the vehicle can be clearly recognized as an experimental racing laboratory itself.
In contrast to the 918 Spyder concept, an unadorned racing ambience predominates inside the 918 RSR. The figure-hugging bucket seat in brown leather alludes to the history of the gentleman driver; the gear flashes on the steering wheel and a recuperation display on the steering column supplies the driver with information.
Instead of the futuristic, ergonomically avant-garde center console with touch-sensitive user interface from the 918 Spyder concept car, the 918 RSR is split by a minimalistic console with rocker switches. Instead of a second seat, the flywheel accumulator is positioned to the right of the console.
This flywheel accumulator is an electric motor, whose rotor rotates at up to 36000rpm to store rotation energy. Charging occurs when the two electric motors on the front axle reverse their function during braking to 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 maneuvers. The flywheel is braked electro-magnetically in this case in order to additionally supply up to 204hp 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 successful 911 GT3 R Hybrid, this additional power can also be used as a consumption aid, depending on the racing situation, to delay pit stops or reduce the fuel tank volume and, therefore, the weight of the vehicle.
With the new 918 RSR racing laboratory, Porsche is elevating this motor racing hybrid concept to an experimental level. In the 918 RSR, ‘Porsche Intelligent Performance’ equates to research into methods for further sustainable efficiency improvement under the intensified conditions of the racetrack, lap times, pit stops and reliability.
Finally, the starting number, 22, pays homage to the anniversary of a further triumph: Back when overall victories in Le Mans were not yet an entirely routine matter within the Porsche racing department, drivers Dr Helmut Marko and Gijs van Lennep were the first to cross the finishing line in the 1971 24-hour classic. The distance record set by their Porsche 917 short-tail coupé – 3315.21 miles at an average speed of 138.13mph –remained unbeaten 39 years until 2010. At the time, the Porsche 917 in the Martini colors was also an experiment and far ahead of its time: for example, its magnesium spaceframe chassis set new standards in the Porsche domain of lightweight construction.