Carrera RSR
The Porsche 911 Carrera RSR, developed 1973-1975 as factory-built racing variant of iconic 911 platform dominating GT category motorsport, features extensively-modified air-cooled flat-six engine available in 2.8-liter specification producing 300 horsepower at 8,000 rpm or enlarged 3.0-liter Type 911/75 developing 330 horsepower at 8,000 rpm with 315 Nm (232 lb-ft) torque through twin-plug ignition, high-lift camshafts, Bosch mechanical fuel injection, and 10.3:1 compression ratio paired with five-speed manual transmission. Extreme lightweight construction achieves approximately 900 kg race weight despite steel roll cage and 120-liter fuel tank through fiberglass body panels, Plexiglas windows, and comprehensive weight reduction program enabling remarkable power-to-weight ratio approaching 367 horsepower per ton creating 290 km/h (180 mph) top speed capability.
The Carrera RSR represents Porsche ultimate expression of naturally-aspirated 911 racing philosophy before turbocharger adoption, featuring dramatically-widened rear fenders accommodating 11-inch Fuchs forged alloy wheels, distinctive ducktail rear spoiler providing high-speed stability, and aggressive aerodynamic package including NACA ducts for brake cooling. Competition success included overall victory at 1973 24 Hours of Daytona, dominant performances throughout IMSA GT Championship, and class victories at various international endurance races establishing RSR as most successful GT racing platform of era. Advanced engineering featured dry-sump lubrication system, fully adjustable suspension with competition-spec Bilstein dampers, upgraded Brembo ventilated disc brakes, and characteristic flat-six exhaust note enhanced through dual megaphone exhaust system. Popular among historic racing enthusiasts and collectors commanding multi-million dollar valuations, the Carrera RSR established foundation for subsequent 935 and 934 turbocharged development while representing pinnacle of air-cooled naturally-aspirated 911 performance combining Porsche legendary reliability with genuine 290+ km/h racing capability establishing motorsport credibility throughout 1970s establishing enduring legacy among most significant competition Porsches ever produced.