The 917/30 was called "the most powerful race car of all times". Depending on the boost pressure of its two turbochargers, the 12-cylinder horizontally-opposed engine's power output is somewhere between 1100 and 1400 bhp. The car, which weighs a mere 800 kilograms, accelerates from a stand-still to 100 km/h in just 2.4 seconds, by which time the driver hasn't even shifted into second gear. It reaches 200 km/h in 5.6 seconds and passes the 300 km/h mark in 11.3 seconds.

The 917/30 was used in 'CanAm' events. At that time, almost everything was allowed, with the engineers' ideas not hampered by weight or engine-size limits for years. For years, McLaren dominated the CanAm series with their potent eight-cylinder Chevys, until Porsche came, saw and won with their turbos.

In 1972, George Follmer took part successfully in a 917/10. The following year, in the fastest race of this series, the winner was Mark Donohue in a 917/30. More Porsches took places two to four and six. This overwhelming supremacy had disastrous consequences for Porsche: The CanAm officials quickly changed the rules so that Porsche's Turbos couldn't participate any more.

 

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." The head of the racing engine and pre-development division at Porsche for many years explains: "Before the 917/30 was developed, the assumption was that the supercharger is only suitable on high speed tracks with no sharp bends, for instance the Indianapolis oval".

Only two 917/30s were built, and one of them has been the star of the museum since 1975. It was completely restored in 2000, with the work not confined to the plastic body. Experts from the Bosch company optimized the 5.4 liter turbocharged engine's throttle response by updating the control units. This also meant that the 24 spark plugs do need to be changed so often. Purists may regret this departure from the original specification, but it does mean that the 917/30 can now participate in renowned historic car events such as the 'Festival of Speed' in Goodwood, without any difficulty.

Technical data
engine: Twelve-cylinder, horizontally opposed, air cooled, four gear driven overhead camshafts
engine size: 5374 ccm
bore x stroke: 90 x 70.4 mm
fuel system: mechanical, indirect injection, 400 l fueltank
power: 1100 - 1400 bhp
powertrain: four-speed gearbox
weight: 800 kg
top speed: depending on the set up, around 400 km/h

Pictures, top: The 917 at the Porsche Museum; below: Mark Donohue at Mosport 1973

 

1) Does motor racing still make sense? Does it help in the development of safer and cleaner cars?

2) How does turbocharging work? What type of chargers (pumps) are used? What sort of combustion engine is most often equipped with a turbocharger?

3) Do you know another term for 'horizontally opposed engine'?
What sets a horizontally opposed engine apart from a V-engine?

4) Draw a diagram (v-t) which shows the acceleration of the 917/30. What rate of acceleration has the 917/30 at 100, 200 and 300 km/h?

5) Why took Porsche part in the Canam series? What does 'CanAm' stand for? Why did they quickly change the rules? Is the series still run?

6) Who was Mark Donohue? What were his achievements?

7) Where is Talladega and Goodwood?