The Porsche 917 was designed to exploit FIA regulations allowing five-litre Group 4 sports cars in the World Sportscar Championship from 1969, and was powered by a flat-12 engine enlarged progressively from 4.5 to 5.0 litres. While the standard short-tailed 917K (Kurzheck) was developed for medium- and high-speed circuits, Le Mans presented a specific aerodynamic challenge: its long, largely uninterrupted straights demanded the lowest possible drag, even at the cost of reduced downforce. Porsche developed the 917LH specifically for this circuit, fielding it only at Le Mans.
The 1970 917LH was developed with assistance from external consultant Robert Choulet and featured a spectacular new long-tail body that achieved very low drag while generating more rear downforce than the problematic 1969 long-tail version. Two examples were entered at the 1970 24 Hours of Le Mans: one by Porsche Salzburg, driven by Vic Elford and Kurt Ahrens, and one by Martini Racing, driven by Willi Kauhsen and Gerard Larrousse and painted in an elaborate pattern of light green whirls on dark blue — earning the nickname "Hippie Car" or "Psychedelic Porsche." The 917LH was some 25 mph faster than the 917K and the rival Ferrari 512S on the straights. Elford qualified the Porsche Salzburg car on pole position, but it retired with engine failure after 225 laps. The Martini 917LH finished second overall in the race, five laps behind the winning Porsche Salzburg 917K of Hans Herrmann and Richard Attwood, which had carried a 4.5-litre engine carefully through the rainy conditions.
The 1971 model was a further development of the 1970 car, incorporating revised suspension, new bodywork with partially enclosed rear wheel covers, and a redesigned front section that addressed the aerodynamic instability that had plagued earlier long-tail variants. Three were built for the 1971 Le Mans race: two entered by JW Automotive and one by Martini International. Jackie Oliver qualified one of the JW cars on pole position — Pedro Rodriguez also set a fastest qualifying lap that, partly due to subsequent circuit changes, stood for decades. Despite their qualifying pace, none of the three 917LHs finished the 1971 race. The race was ultimately won by the Martini Racing 917K of Helmut Marko and Gijs van Lennep, which set an overall distance record that stood until 2010 and broke four Le Mans track records that year, all set by 917 variants.
The 917LH bodywork created lower aerodynamic drag than the standard 917K configuration at the cost of reduced downforce, a trade-off judged acceptable only for Le Mans where sustained speed mattered more than cornering grip. The factory deployed three distinct car types across the season — the 908/03 for slow and twisty tracks, the 917K for medium and high-speed circuits, and the 917LH for Le Mans alone — reflecting a level of event-specific engineering specialisation unusual even at the highest levels of sportscar racing.
The 917LH variants form a crucial chapter in Porsche's dominance of the 1970 and 1971 World Sportscar Championship seasons. The 1970 race gave Porsche its first ever overall Le Mans victory, achieved not by the LH but by the more conservative 917K that the LH helped define by contrast. The 1971 LH's failure to finish despite pole position underlined the tension between aerodynamic optimisation and mechanical reliability over 24 hours, a lesson Porsche's subsequent Le Mans programmes would carry forward.