Detroit 2011: Porsche 918 RSR
By Chris Haak
Purists and automotive writers alike love to complain about the damage that Porsche’s move into SUVs and large, heavy sedans has done to the company’s brand and its heritage. The company and its defenders typically counter those criticisms by noting that without the likes of the Cayenne and Panamera, amazing sports cars like the 911 GT3 would not be possible.
Also likely not possible without the help of the fat, high-margin cars: roadgoing race cars like the Porsche 918 RSR. Built as a fixed-roof version of the car that surprised and delighted many observers – the 918 Spyder hybrid, which Porsche later announced would go into series production – the 918 RSR actually goes in a very different direction than the 918 Spyder concept did.
The 918 RSR incorporates a version of the 911 GT3 R hybrid’s powertrain to not only conserve some fuel, but to enable a type of “super boost” mode that provides additional power for acceleration and overtaking maneuvers. The 918 RSR’s powertrain works by combining a screaming 563-horsepower V8 (which makes its power peak at 10,300 RPMs) with electric motors fitted to each of the front wheels. The electric motors each contribute 75 kW (150 kW combined), for a total peak drive output of 767 horsepower.
The electric motors get their power thanks to a flywheel accumulator, which is an electric motor that rotates at 36,000 RPMs perched on the driver’s right side where a passenger seat would normally be. During braking, the axles’ electric motors engage in regenerative braking, sending energy to the flywheel. Upon the press of a button, the driver can call on the stored reserve of power and send it back to the wheels’ electric motors. The electric motors also boast a torque-vectoring function.
The 918 RSR itself is built on a carbon fiber reinforced plastic (CFRP) monocoque, which is extremely light and stiff – and very expensive to build and repair. The car is designed in a mid-engine configuration (rear-mid, specifically), and a paddle-shifted six-speed constant mesh transmission helps put the V8’s power to the ground.
The car certainly features an attractive shape, with the passenger compartment nearly perfectly centered on the car’s profile. The base of the windshield is curved, as the windshields in classic Porsches are, and the car has a very fluidic, organic shape. Muscular wheel arches somewhat offset the inherent femininity of the 918 RSR’s shape, and if you had any doubts about the car’s street cred, just check out the giant wing and prominent side exhaust outlets.
As in many supercars, front-hinged doors just won’t do, and the 918 RSR has upward-opening doors. The interior of the 918 RSR, befitting its status as Porsche’s new “experimental racing laboratory,” eschews the creature comforts of other supercars (and indeed, Porsche’s 918 Spyder concept) in favor of a businesslike form-follows-function cockpit. Minimalism is the name of the game here, and if you had any doubts about this car’s mission, just glance over at the giant flywheel riding shotgun.
It’s not clear what series, if any, would have such liberal rules as to allow a car with this much technology to compete. Formula 1, arguably the highest level racing series with the most elite drivers, has a number of technology-limiting rules in place. There’s always the possibility that Porsche could just just create its own racing series just for this car – or simply use the 918 RSR to attempt some lap records on the Nordschliefe.
The gallery below includes live photos of the 918 RSR from the show.