Porsche 917
The type 917 gave Porsche its first overall wins at the 24 hours of Le Mans in 1970 and 1971. Powered by the type 912 flat 12 engine of 4.5, 4.9, 5 and later 5.4 liters the long-tailed version was capable of over 240 miles per hour down the Mulsanne Straight. it is one of the most iconographic sports racing cars of all time.
History
In April 1968 the CSI announced tha the minimal production figure to compete in the Sport category was reduced from 50 to 25 for the 1969. Starting in July 1968 Porsche made a surprising and very expensive effort to conceive, design and build a whole new car for the Sport category with one underlying goal: to win its first overall victory in the 24 Heures du Mans. In only ten months the Porsche 917 was developed, which incorporated remarkable technology: Porsche’s first 12-cylinder engine and a lot components from titanium, magnesium and exotic alloys.
On March 12 1969, the first 917 was displayed ot the Geneva Motor Show painted white with a green nose). Brief literature on the car detailed a cash price of DM 14,000 or approx. £16,000
When Porsche was first visited by the CSI inspectors only three cars were assembled, 18 being assembled and sets of parts for seven complete cars were present. Porsche argued that if they assembled the car they would then have to take them apart again to prepare the cars for racing. The inspectors refused the homologation and asked to see 25 assembled cars.
On April 20 Ferdinand Piëch displayed 25 917s parked in front of the Porsche factory to the CSI inspectors. Piech even offered one the opportunity to drive one of the cars, which he declined.
It soon appeared that the Porsche 917 did not work well on the racing track, as its aerodynamics were developed for low drag rather than downforce. This was necessary for all former underpowered Porsches in order to do well on the fast straights of Le Mans but as the car was 30km/h faster than anything previously built for le Mans the body was generating a significant lift on the straight.
Brian Redman recalls that "it was incredibly unstable, using all the road at speed." Many thought that the 4,5 liter engine was too much for the frame. At its competition debut at the Nürburgring 1000km, all works drivers preferred the 908 over the 'unsafe' 917, which was driven by two hired drivers.
During June 1969 Enzo Ferrari sold half of his stock to Fiat. Ferrari used some of that money to build 25 cars in order to compete with the Porsche 917: the Ferrari 512, powered by a 5 liter V12, was introduced for the 1970 season.
Disappointed by the poor results of the 917 in 1969 and facing a new competition, Porsche concluded an agreement with John Wyer and the Gulf Team, which became the official Porsche team, and also the official development partner. During tests in Zeltweg Wyer's engineer John Horsmann had the idea to increase downforce to the expense of drag, a new tail was molded with aluminum sheets taped together. This worked well as the new short tail gave the 917 better stability. The new version was called 917 K (Kurzheck).
A new low drag version of the 917 was developed for Le Mans with support from the external consultant Robert Choulet. The 917 LH (Langheck) featured a spectacular new "Long Tail" body which had very low drag and better stability than the 1969 version.
At the end of the 1970 season Ferrari had entered in some races a new version of the 512, the 512 M (Modificata). The 512 M had a new bodywork built on the same aerodynamics doctrine than the Porsche 917K. At the end of 1970 the 512 M was faster than the 917s, at least on some tracks.
During the 1971 season the FIA decided to ban the loop hole Sport category for 1972, so the big 917s and 512s would have to retire at the end of a year which they would surely dominate again.
Surprisingly Ferrari decided to give up any official effort with the 512 in order to prepare the 1972 season and a new prototype, the 312 PB was presented and engaged by the factory in several races. But many 512s were still raced by private teams and most of them converted to M specification. Being cheaper than the 917 K, the 512 M appeared as a bargain for customers at the end of 1970.
Roger Penske bought a used 512 M 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 extend 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" made the pole but finished the race at the sixth position after making contact with Pedro Rodrigez'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 512 M "Sunoco" forced Porsche to pursue his effort of research and development on the 917: The 917 K 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 917/20 was painted in pink for the 24 hours race with names of pieces of meat written across it, the car earned the nickname "Pink Pig".
The 917/30 was one of the most powerful sports cars ever built. The 5.4 liter 12 cylinder could produce 1500 bhp with twin turbochargers attached though it usually raced with around 1100bhp to preserve the engine. The 917/30 dominated in the Can-Am series. The 917/30 could go from 0-60 mph in about 2.1 seconds with a top speed of 238 mph.
The 917 was made into a Movie Star by Steve McQueen in Le Mans.
Books about the 917
1976 -- The Fabulous Porsche 917 (1st edition) by P Hinsdale (ISBN 0-87799-052-2)
1986 -- PORSCHE 917 SUPER PROFILE by J Allen (ISBN 0-85429-605-0)
1987 -- PORSCHE 917 THE ULTIMATE WEAPON by I Bamsey (ISBN 0-85429-605-0)
1987 -- Porsche 917, Kimberleys Sportscar Guide by Michael Cotton (ISBN 0-946132-91-7)
1999 -- Porsche 917, the Winning Formula by Peter Morgan (ISBN 1-85960-633-4)
2000 -- Porsche 917, Unique Motor Books (ISBN 1-84155-297-6)