The 1971 24 Hours of Le Mans was the 39th Grand Prix of Endurance, and took place on 12 and 13 June 1971. It was the ninth round of the 1971 International Championship for Makes.
At the end of the 1970 season, Ferrari had entered a new version of the 512 in some races, the 512M (Modificata). The 512M had a new bodywork built on the same aerodynamics doctrine of the Porsche 917K. During the 1971 season, the FIA decided to eliminate the Sport category for 1972, so the big 917s and 512s would have to retire at the end of a year. Ferrari decided to give up any official effort with the 512 in order to prepare the new 312PB for 1972, but many 512s were still raced by private teams and most of them converted to M specification.
Roger Penske bought a used 512M chassis that was totally dismantled and rebuilt. The car was specially tuned for long races receiving many unique features, among them were a large rear wing and an aviation inspired quick refueling system. The engine was tuned by Can-Am V8 specialist Traco; this engine was probably able to deliver more than 600 hp (450 kW). As of today it's impossible to know to what extent Penske's initiative was backed by Ferrari works. This 512 M, painted in a blue and yellow livery, was sponsored by Sunoco and the Californian Ferrari dealer Kirk F. White. This car made the pole position for the 24 Hours of Daytona and finished second despite an accident. For the 12 Hours of Sebring the Sunoco 512 won the pole, but finished the race in sixth position after making contact with Pedro Rodríguez's 917. Despite this misfortune, the car had proved to be a serious opponent for the 917. Not only this car was the fastest on track in Daytona and Sebring but it was also the car that had the shortest refueling time.
The presence of the Sunoco 512M forced Porsche to pursue his effort of research and development on the 917. The 917K tail was modified, and the 917 LH aerodynamics received further improvements. New magnesium chassis were developed. An entirely new car, the 917/20 was built as test-bed for future Can-Am parts and aerodynamic low-drag concepts. The chunky car was painted in pink for the race with names of pieces of meat written across it, earning it the nickname "Pink Pig". During the 1970-71 race period the 917 won 14 of the 21 races it entered and achieved second place in two of those races.
A modified Ferrari 512 featuring a narrowed cockpit (built around a Porsche 917 windshield) was entered by Scuderia Filipinetti, for Mike Parkes and Henri Pescarolo. The car was christened 512F.
Matra entered only one 660 for Chris Amon and Jean-Pierre Beltoise.
The Ford-Cosworth DFV made its Le Mans debut in Guy Ligier's new JS-3. The engine was limited to 8800 rpm, allowing around 400 hp (300 kW).
The 1971 Le Mans race was the first race to start using the safer rolling start method (the "Indianapolis start"), rather than the "Le Mans start" method that had been used in previous Le Mans races, and continues that way now. Despite the much-vaunted speed of the Porsches, the ACO speedtrap clocked a Ferrari at 359 km/h (222.6 mph), the highest speed reached by any car in qualifying. This would be eclipsed during the race when a Porsche was timed at 362 km/h (224.4 mph). The fastest qualifying lap however, was recorded by the Rodriguez/Oliver 917LH at 3:13.9. Long-tail Porsches occupied the first three places, with the Martini-sponsored entry of Elford/Larrousse second and the Gulf-Wyer car of Siffert/Bell 3rd. The first Ferrari was the Sunoco 512M of Donohue/Hobbs in fourth slot, some five seconds in arrears of the pole sitter.
Pedro Rodríguez and Jackie Oliver's 917 lead the first hours. At 7:00 p.m. the Sunoco was third. At 8:16 p.m., Donohue pitted the Sunoco Ferrari early. The Traco-tuned engine died. At dawn the Matra was in an amazing second position. But at 9:40 a.m., Amon stopped in the long straight and stepped out of the Matra roadster. He had run out of fuel due to a faulty fuel-metering, and the pits were too far away to push the car.
Despite the extremely high speeds of the long tail versions, the 1971 Le Mans race was again won by a short tail car but with a magnesium chassis. The white No. 22 Martini Porsche of Helmut Marko and Gijs van Lennep completed 397 laps, which set a new distance record of 5,335.313 km (3,315.210 mi). That record, which many believed it would be unbreakable because of the lack of chicanes, would however be broken in 2010 when three Audi R15 TDI plus cars ran by Joest Racing ran in excess of that distance, despite the chicanes put since 1990 and other changes to the Circuit de la Sarthe course throughout the years (392 laps would be the amount of laps that would exceed the distance record in the 13.629 km (8.469 mi) configuration that was in use in 2010); all three ran at least 394 laps, with the winning car, the #9 of Timo Bernhard, Romain Dumas and Mike Rockenfeller, also ran 397 laps but ran a distance of 5,410.7 km (3,362.1 mi); the 1971 race was run in a 13.469 km (8.369 mi) configuration, which was the last race under that configuration; the 1972 race (up until 1978) ran in a modified 13.64 km (8.48 mi) configuration; since then, eight more modifications were made up to today's Circuit de la Sarthe, which stands at 13.629 km (8.469 mi) as of 2010 (the configuration was first run in 2007).