The 917/30 was the final and most extreme iteration of the Porsche 917 programme, itself developed as a direct evolution of the 917/10 that had won the 1972 Can-Am championship with George Follmer driving for Roger Penske. For 1973, Porsche lengthened the wheelbase to accommodate a revised engine and fitted entirely new bodywork. The engine was the twin-turbocharged flat-12, bored out from 5.0 to 5.374 litres (327.94 cu in), with a 90.0 x 70.4 mm bore and stroke, producing around 1,100 horsepower at 7,800 rpm in race trim. Higher boost settings used in qualifying and testing brought output significantly above that figure.
A total of six chassis were built. The primary entry was the Roger Penske car driven by Mark Donohue, who had been sidelined from most of the 1972 season by injury but returned for 1973 as the undisputed lead driver.
Mark Donohue won the 1973 Can-Am championship in the Penske 917/30, winning all races in the season except two: Charlie Kemp won at Mosport and George Follmer won at Road Atlanta. The scale of the car's advantage was such that Can-Am racing lost its competitive credibility; most of the opposition consisted of private 917/10K cars, as McLaren had already withdrawn from the series. The 917/30's dominance is often cited as a contributing factor in Can-Am's subsequent decline as a major international racing formula.
On 9 August 1975, Porsche and Penske took their 917/30 to Talladega Superspeedway for a final record attempt. With Mark Donohue driving, the car averaged 221.160 mph (355.923 km/h) over a closed circuit to set a new FIA closed-circuit speed record. The record stood until 1980. This was the last major competitive accomplishment for Donohue; he was fatally injured in practice for the Austrian Grand Prix just one week later.
The 1974 SCCA introduced a maximum fuel consumption rule of 3 mpg to constrain the turbocharged cars, effectively rendering the 917/30 uncompetitive. The Penske car competed in only one race in 1974, and some customers retrofitted their 917/10K cars with naturally aspirated engines. The 917/30 programme ended with the 1974 season.
The 5,374 cc twin-turbocharged flat-12 engine used a 90.0 x 70.4 mm bore and stroke configuration. The spaceframe chassis incorporated a longer wheelbase than the 917/10. In race trim the engine produced approximately 1,100 bhp (820 kW) at 7,800 rpm; the 917/30 was the only Can-Am championship-winning car not powered by a Chevrolet engine, breaking the tradition that had defined the series since its founding.
The 917/30 stands as the peak expression of the naturally evolved turbocharged racing car before fuel consumption regulations and displacement limits constrained output. Its power figures were not matched in a production racing context until the turbocharged Group C and CART programmes of the 1980s. The 917 programme as a whole — encompassing the original prototype, the 917K that gave Porsche its first Le Mans victories in 1970 and 1971, the 917LH long-tail, and the Can-Am 917/10 and 917/30 — transformed Porsche from an underdog specialist to the dominant force in international sportscar racing over just four years. The technology and engineering experience derived from the 917 turbo programme fed directly into subsequent Porsche racing efforts including the 936, 934, and 935.