1972 Porsche 911 RSR

Porsche's legacy is tied to both sports cars and motorsports. The racing department, since the mid-1960s, had created a new prototype racer nearly every year. It began with the 904 Sports GT model of 1964 and was followed by the 906, known as the Carrera 6, which would be the last street-legal race car from Porsche. The proceeding eight-cylinder 908 won the World Championship in 1969 followed by the legendary 917 the following season. With this new race car, Porsche became a contender for outright victory in every race it entered. Over a two-year period, the Porsche 917s won 15 of the 24 World Championship races they entered. Eventually, they would win more races in the Can-Am, Interserie, and Manufacturers World Championship than any other two-seater racecar ever produced. Victories were earned on the worlds greatest racing stages including Sebring, Daytona, Le Mans, Monza, Spa, and the Nürburgring

After the 1971 season, the 917 became ineligible to race in the world championship, so Porsche turned its attention to the nearly no-limit Group 7 class of the European Interserie and the North American SCCA Can-Am Challenge (Can-Am). The 917 (917/10 and 917/30) competed until the oil crisis era of 1973 brought its career to an end. (The Penske 917/30 raced in one race in 1974 and several customers continued to race with naturally aspirated engines in their 917/10K).

Having proven they could dominate in international competition, Porsche re-focused its efforts from sports prototypes to production-based machinery. The German manufacturer began with its proven 911 and with further development transformed it into a racing car. The 2.4-liter 911 S received numerous improvements and with sufficient examples produced, was the RS (representing Rennsport in German, meaning race sport) 2.7 Carrera was homologated to race in 1972 for Group 4 competition. The formula was taken a step further, creating the even more radical and modified RSR Carrera to compete in the new Group 5 competition.

The Carrera 2.7 RS was given a larger 2,687cc engine offering 210 horsepower with Bosch mechanical fuel injection, modified suspension, larger brakes, wider rear wheels, and a 'ducktail' rear spoiler. The RS Touring weighed about 2,370 lbs. while the Sport Lightweight was about 100 pounds lighter, achieved by using thinner gauge steel for its body shells and thinner glass. In total, 1,580 examples were made, with 49 Carrera RS built with the 2,808cc engines rated at 300 horsepower.

Further development followed for the 1973 season, with 55 examples of the RSR eventually built. Based on the Carrera RS 2.7, the RSR 2.8 (option M491) received a weight reduction of 80 kg, and the displacement increased by 119cc. The engine received twin-plug ignition, a higher compression ratio, larger valves, and extensive lightening of internal components resulting in an increase of horsepower to over 300 bhp. To help deliver the power to the ground, wider Fuchs wheels and wheel arches were installed as well as a low-level front air dam with an integral oil cooler. The 917-based braking installed providing exceptional stopping power and a refined suspension enhanced drivability and handling. The chassis was further strengthened to help code with the increase in power.

by Daniel Vaughan | Feb 2020