Rule changes for the World Championship of Makes eliminated the stunning Porsche 917 during the early 1970s allowing the factory to instead develop the car for the open-top Canadian-American (CanAm) Championship in North America.
Teams from McLaren, Lola and Chaparral were attracted to the 200 mile Sprint races of the formula and the rule book permitted almost anything, including free engine displacement and the use of turbochargers.
Porsche used its new found skills with forced induction to attach two exhaust-driven turbochargers to the flat-twelve engine of the 917. The result had a displacement of 5.4-litres and produced at least 1,100 hp, making it one of the most powerful racing cars ever built. Depending on the boost pressure, the engine’s power output is somewhere between 1,100 hp and 1,400 hp.
The car, which weighs a mere 800 kg, accelerates from 0 to 62 mph in just 2.4 secs, by which time the driver hasn’t even shifted into second gear! The 917/30 can reach 120 mph in 5.6 secs and passes the 180 mph in 11.3 seconds.
The 917/30 went on to dominate in the 1973 CanAm with the top four places in the final points being taken back to Stuttgart and Porsche factory driver, Mark Donohue, set a closed circuit record of 222 mph (355.85km/h) around the Talladega Oval, Alabama. A time that still ranks as one of the fastest race laps ever.
The turbocharged twelve-cylinder engine in the 917/30 set new standards that influenced areas well beyond race car construction. Engine designer Hans Mezger recalls: “With this engine, it was obvious for the first time that turbocharging could also be used for tracks with lots of corners. Before the 917/30 was developed, the assumption was that the turbocharger is only suitable on high-speed tracks with no sharp bends, for instance the Indianapolis oval.”
Only two examples of the 917/30 were built, and one of them has been the star of the Porsche Museum since 1975. The car was completely restored in 2000 with the bodywork and engine completely overhauled. Experts from the Bosch company optimised the engine’s throttle response by updating the control units. This also meant the 24 spark plugs do not need to be changed so often. Purists may regret this departure from the original specification, but it does mean the 917/30 can participate in events like the Goodwood Festival of Speed, at much lower speeds, without any difficulty.
Engine Twelve cylinder, air-cooled, two-valve, opposed-piston, turbo engine, four cog-wheel overhead camshafts
Power 1,100 hp – 1,400 hp at 7,800rpm
Fuel System Indirect mechanical fuel injection, 400-litre fuel tank
Transmission Four-speed gearbox, rear-wheel drive, limited-slip differential
Chassis Light metal tubular spaceframe, plastic body, independent suspension, coil springs, vented disc brakes
Dimensions Wheelbase 2500 mm, length 4262 mm
Performance Top speed approximately 240 mph