The RSR designation emerged directly from the Carrera RS 2.7 homologation exercise of 1972–1973. Porsche needed to build a minimum of 500 road cars — the Carrera RS 2.7 — to qualify for FIA Group 4 Special GT class racing. The factory produced 1,580 Carrera RS 2.7 units, comfortably exceeding the threshold, and then converted 55 of these into the competition-focused RSR specification under the M491 conversion code.
The Carrera RSR 2.8 used a 2,808 cc engine (bore and stroke of 92 mm × 70.4 mm, coded 911/72) producing approximately 312 PS (229 kW). Compared to the road-going RS, the RSR received wider front and rear wheel arches to accommodate broader wheels and tyres, revised suspension settings, and stripped competition bodywork. The RS stood for Rennsport — racing sport — while the additional R indicated the car's pure racing intent.
The RSR 2.8 debuted at the 1973 24 Hours of Daytona, where Peter Gregg and Hurley Haywood won outright. This was a remarkable result for a production-derived GT car, as the RSR defeated purpose-built prototypes in the race's overall classification under that year's rules. The car also achieved class victories at the 12 Hours of Sebring and performed strongly at European circuits, demonstrating that the basic 911 architecture remained highly competitive when developed for circuit racing.
At the 1973 Targa Florio, run over Sicilian public roads against factory prototype entries from Ferrari and Alfa Romeo, a production-based 911 Carrera RS (the F series road car) defeated its opponents outright — a result highlighting how effective the platform had become.
For 1974, Porsche developed two further RSR variants targeting different aspects of endurance racing. The Carrera RSR 3.0 used a 2,993 cc engine (coded 911/74, 95 mm bore × 70.4 mm stroke) producing 315 PS (232 kW), and was produced in low volume for outright GT racing. The chassis was derived closely from the 1973 RSR and used brake components from the Porsche 917.
Alongside the RSR 3.0, Porsche also developed the Carrera RSR Turbo 2.1, fitted with a turbocharged 2,142 cc flat-six (coded 911/76) that, under the FIA's 1.4× equivalency formula for turbocharged engines, was treated as a 3.0-litre-class car but produced approximately 500 PS (368 kW). The RSR Turbo came second overall at the 1974 24 Hours of Le Mans — a landmark result, as it demonstrated the potential of turbocharging in endurance competition and directly informed Porsche's subsequent turbocharged racing programme. The engine developed for the RSR Turbo became the foundation for the Porsche 934 and 935 programmes that followed.
Across its variants, the 911 Carrera RSR accumulated an exceptional competition record through the mid-1970s:
The 1973 RSR 2.8 won outright at the 24 Hours of Daytona in its debut season, a result that underscored how effectively Porsche had developed the 911 platform beyond its road-car origins. The RSR also recorded multiple victories at the 1000 km Nürburgring and the 12 Hours of Sebring during 1973 and 1974.
The RSR Turbo's second-place finish at Le Mans in 1974 opened the turbocharging era for Porsche in endurance racing, leading directly to the 935's outright Le Mans victory in 1979 and Porsche's broader dominance of sports car racing into the 1980s.
Trans-Am Series and IMSA competition also saw RSR participation, with the car proving adaptable to the variety of circuits and regulations encountered in North American road racing.
The Carrera RSR occupies a pivotal place in motorsport history as the car that bridged the naturally aspirated Carrera RS road cars and Porsche's turbocharged racing future. By winning outright at Daytona with a GT-class car and by demonstrating the potential of a turbocharged 911 derivative at Le Mans, the RSR programme shaped the entire subsequent direction of Porsche's racing strategy through the late 1970s and 1980s. The 934, 935, 936, and ultimately the 956 and 962 all drew on lessons learned through the RSR programme, making it one of the most consequential development exercises in Porsche's racing history.