Porsche creates first street-legal 963

Porsche completed the first legal circulation of a 963 prototype on French public roads. The 963 RSP, a special version of the IMSA and WEC winner, obtained official authorization to drive with a manufacturer 'W' license plate. The project pays homage to Count Rossi, who in April 1975 drove a race-prepared 917 from the factory in Zuffenhausen to Paris.

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Project origin at Road Atlanta

The idea emerged during a meeting at Road Atlanta between Timo Resch, president of Porsche Cars North America, Thomas Laudenbach from Porsche Motorsport and Urs Kuratle, director of Factory Racing LMDh. The three proposed repeating the 917's journey with current technology. Roger Penske and Jonathan Diuguid from Porsche Penske Motorsport supported the concept, with Penske nominated as the customer for the car bearing his initials.

Changing eras: mandatory homologation vs pure prototypes

The 60s-80s required manufacturers to produce street versions to compete. Group 4 demanded at least 400 units in 12 months, ensuring the car wasn't competition-exclusive. The Porsche 911 Carrera RSR and Ferrari 365 GTB/4 Daytona Competizione complied with these rules.

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Group 5 allowed extreme modifications starting from cars with 25 or 400 base units, depending on subcategory. The Porsche 935 and Lancia Beta Montecarlo Turbo took advantage of these regulations. Group B reduced the requirement to 200 units, enabling cars like the Ferrari 288 GTO.

Group C changed everything in 1982, eliminating street homologation. Pure prototypes like the Porsche 956/962, Sauber-Mercedes C9 and Jaguar XJR-9 only limited fuel consumption. Current LMDh continues this philosophy, allowing the 963 RSP to exist as a unique specimen without series production.

Adaptations for road use

Engineers raised the ride height to its maximum available setting and configured the Multimatic DSSV dampers to their softest setting. The control unit was reprogrammed to activate turn signals and adjust headlights according to road requirements. 18-inch Michelin rain tires on OZ forged wheels completed the changes.

Additional modifications included a functional horn, closed vents in front and rear fenders, removal of blank plates from the rear wing, and license plate brackets. The hybrid system was remapped to smooth out the MGU's power delivery, more appropriate for urban use.

First application of series paint on a 963

The 963 RSP received automotive paint instead of traditional racing vinyl. The process required special techniques due to the ultra-lightweight carbon fiber and Kevlar construction. Grant Larson, director of Special Projects at Style Porsche, verified the 'Martini Silver' color using Porsche Museum archives, applying triple lacquer layers.

An enamel Porsche emblem replaced the standard sticker on the nose, a detail shared with the original 917. 1970s-style Michelin logos on the tire sidewalls completed the retro aesthetic.

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Leather and Alcantara interior

The cabin incorporates finishes in soft tan leather and light Alcantara, following Count Rossi's choices from 50 years ago. The carbon fiber monoblock seat received center padding and a fixed headrest mounted on the rear bulkhead. Seat climate control systems remained active.

Details include reupholstered leg cushions, light Alcantara headliner and pillars, leather-wrapped steering wheel, and a 3D-printed removable cupholder. A panel next to the driver houses the Peltor headset, spare steering wheel and the laptop needed to start the car, along with Roger Penske's custom helmet.

V8 biturbo engine derived from the RS Spyder

The 4.6-liter powerplant derives from the RS Spyder program that won all American Le Mans Series LMP2 titles between 2006-2008. The unit grew from 3.4 liters before powering the 918 Spyder in 2013. The flat-plane crankshaft and short stroke allow low mounting, optimizing the center of gravity.

Van der Lee turbochargers generate moderate boost and are located on the hot side to improve throttle response. Total power reaches approximately 680 hp, with 80% of components shared with the 918 Spyder, already designed for hybrid integration.

800-volt hybrid system

The Bosch motor generator unit (MGU) is housed between the combustion engine and the Xtrac seven-speed sequential gearbox. The complete system operates up to 800 volts with a 1.35 kWh Williams Advanced Engineering battery available during acceleration.

The MGU delivers 30-50 kW in short bursts without altering the powertrain's total output. When electric boost activates, the combustion engine's power - which reaches over 8,000 rpm according to Balance of Performance - automatically decreases. The complete system was remapped to run on commercial gasoline.

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First kilometers on public roads

It was an experience that will stay with me for life. Driving on public roads with a 917 beside me felt unreal. The car behaved perfectly, more friendly and forgiving than the standard 963.

The modifications allowed obtaining a French 'W' manufacturer license plate with special authorization from local authorities and support from the Automobile Club de l'Ouest. Roger Penske received custom equipment: a carbon fiber helmet with Martini Silver accents and a Snap On tool set with coordinated finishes.

Exhibition schedule

The 963 RSP will be publicly displayed at Circuit de la Sarthe during the 24 Hours of Le Mans before moving to the Porsche Museum in Stuttgart. In July it will appear alongside the original 917 at the Goodwood Festival of Speed.

The project will remain as a unique specimen without homologation for Porsche's regular lineup, fulfilling Roger Penske's desire to maintain the authenticity of its origin with minimal changes to the base race car.