Porsche 917 is First Produced
The Porsche 917 is a racecar that 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, or 5 litres, the long-tailed version was capable of a 0-62 mph (100 km/h) time of 2.7 seconds (917/30 0-200 km/h 5.3 seconds) a top speed of over 240 mph (390 km/h).
All of the 917 versions in total are 6 unique cars. The least-powered version is the 917K (the most successful), produces around 620bhp. There is also a long-tail version (917LH), a "pig" version, modified 917K with the 908 rear spoilers and the 917/30. In the 1973 Can-Am series, the turbocharged version Porsche 917/30 developed over 1,100 bhp (820 kW), and as much as 1,580 bhp (1,180 kW) in qualifying tune.
The 917 is one of the most iconic sports racing cars of all time, largely for its high speeds and high power outputs, and was made into a movie star by Steve McQueen in his 1971 film Le Mans.
2009 marks the 40th anniversary of the 917 and Porsche will hold special birthday celebrations at this year's Goodwood Festival of Speed (3-5 July).
In an effort to reduce the speeds generated at Le Mans and other fast circuits of the day by the unlimited capacity Group 6 prototypes (such as the 7 litre Ford GT40 Mk.IV and 4 litre V12 Ferrari P) the Commission Sportive Internationale (then the independent competition arm of the FIA) announced that the International Championship of Makes would be run for 3 litre Group 6 prototypes for four years from 1968 through 1971. This capacity reduction would also serve to entice manufacturers who were already building 3 litre Formula One engines into endurance racing.
Well aware that few manufacturers were ready to take up the challenge immediately, the CSI also allowed the participation of 5 litre Group 4 Sports Cars, of which a minimum of 50 units had to be manufactured. This targeted existing cars like the aging Ford GT40 Mk.I and the newer Lola T70 coupe.
In April 1968, facing few entrants in races, the CSI announced that the minimal production figure to compete in the Sport category of the International Championship of Makes (later the World Sportscar Championship) would be reduced from 50 to 25, starting in 1969 through the planned end of the rules in 1971. With Ferrari absent in 1968, mainly Porsche 908 and Ford P68 were entered there, with the Ford being a total failure. As a result, old 2.2. litre Porsche 907 often won that category, with John Wyer's 4.7 litre Ford GT40 Mk.I taking wins at faster tracks.
Starting in July 1968, Porsche made a surprising and very expensive effort to take advantage of this rule. As they were rebuilding race cars with new chassis every race or two anyway, selling the used cars to customers, they decided to conceive, design and build 25 versions of a whole new car with 4.5 litre for the Sport category with one underlying goal: to win its first overall victory in the 24 Hours of Le Mans on May 14 1970. In only ten months the Porsche 917 was developed, based on the Porsche 908.
When Porsche was first visited by the CSI inspectors only three cars were completed, while 18 were being assembled and seven additional sets of parts were present. Porsche argued that if they assembled the cars 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 and working cars.
On March 12, 1969, a 917 was displayed at the Geneva Motor Show, painted white with a green nose and a black #917. Brief literature on the car detailed a cash price of DM 140,000, approximately £16,000 at period exchange rates - or the price of about ten Porsche 911s. This price did not cover the costs of development.
On April 20 Ferdinand Piëch displayed 25 917s parked in front of the Porsche factory to the CSI inspectors. Piëch even offered the opportunity to drive any of the cars, which was declined.
The car was built around a very light spaceframe chassis (42 kg (93 lb)) which was permanently pressurised with gas to detect cracks in the welded structure. Power came from a new 4.5 litre air cooled engine designed by Hans Mezger. The 'Type 912' engine featured a 180° V-engine layout, twin overhead camshafts driven from centrally mounted gears and twin spark plugs fed from two distributors. The large horizontally mounted cooling fan was also driven from centrally mounted gears. The longitudinally mounted gearbox was designed to take a set of four or five gears.
To keep the car compact despite the large engine, the driving position was so far forward that the feet of the driver were beyond the front wheel axle.
The car had remarkable technology: Porsche’s first 12-cylinder engine, and many components made of titanium, magnesium and exotic alloys that had been developed for lightweight "Bergspider" hill climb racers. Other methods of weight reduction were rather simple, such as making the gear shift knob out of Balsa wood.
In testing, it soon appeared that the Porsche 917 did not work well on the race track. Brian Redman recalls that "it was incredibly unstable, using all the road at speed." Many thought that the 4.5 litre engine was too much for the frame. The suspension and the stability of the frame were suspected, but modifications did not improve the problem. It was finally determined that the "long tail" body was generating significant lift on the straights, as the 917 was 30 km/h (19 mph) faster than anything previously built for Le Mans. As with former underpowered Porsches, the 917 aerodynamics had been optimized for low drag in order to do well on the fast straights of Le Mans, Spa, Monza and elsewhere. The significance of downforce for racing was not yet fully realized even though Can-Am and F1 cars were using wings by that time.
Before its competition debut on 11 May 1969 in the 1000km Spa, the weather conditions prevented further improvements in tests. Jo Siffert/Redman managed to clock an unofficial lap time of 3:41.9 which would have beaten the pole of 3:42.5 set by a Lola, but they chose to use the 908LH long tail with which they won the race and set the fastest lap at 3:37.1. Gerhard Mitter/Udo Schütz actually started the race from 8th, but their already ailing engine failed after one lap.
Three weeks later for the 1000km Nürburgring, all works drivers preferred the 908 over the 917 which was, despite some modifications, not suited for the twisty track. As it was necessary to promote the car in order to sell the surplus ones, Porsche asked BMW for the services of their factory drivers Hubert Hahne and Dieter Quester. They practised, but Munich declined permission to have them race, so Englishman David Piper and Australian Frank Gardner were hired on short terms. They drove the 917 to an eighth place finish behind a Ford and an Alfa, while the factory's armada of six 908/02 spyders scored a 1-2-3-4-5 win after the only serious competition, a sole Ferrari 312P, failed.
At the 1969 24 Hours of Le Mans, the 917s were quickest in practice. Soon after the start the poor handling of the 917 and the inexperience of one of the drivers resulted in drama: British gentleman-driver John Woolfe crashed his Porsche 917 at Maison Blanche on lap 1, dying as a result. Woolfe was the first privateer to race a 917. The works 917s led the race for hours, but did not make it through the night. At the end, Hans Herrmann's 908 remained as the only Porsche that could challenge for the win, but Jacky Ickx's more powerful Ford won once again, by a mere 120 metres (390 ft).
During June 1969, Enzo Ferrari had sold half of his stock to FIAT, and used some of that money to build 25 cars powered by a 5 litre V12 in order to compete with the Porsche 917: the Ferrari 512 would be introduced for the 1970 season.
At that time, the 917 already had several races under its belt, yet no success. The first win came in the last race of the championship season, the 500 km Zeltweg. Jo Siffert and Kurt Ahrens succeeded in the privately entered Porsche 917 of German Freiherr von Wendt. At that time, the factory had started to focus on development, leaving the time-consuming trips to races to customer teams.
Just because we love it….and because it's just turned 40.
This week marks the 40th anniversary of the Porsche 917.
The car was first displayed at Geneva on March 12, 1969.
Development of the 917 commenced in July of 1968 in complete secrecy to avoid leaked information of its existence reaching Porsche’s number one competitor – Ferrari. The car features a 4.5 lite flat 12 engine and a spaceframe that many consider too light and flexible, however; during the development period Porsche also developed a flat 16 prototype designed for a capacity up to 7.2 litres.
The Spa 1000km of 11 May 1969 saw the 917’s competition debut.
The car was initially deemed “incredibly unstable” by development driver Brian Redman and “extremely dangerous” by Hans Herman.
However an intense development programme through 1969 saw the car ultimately developed into one of the most successfully race cars of all time. It went on to win Le Mans in 1970 and returned in ’71 with the Martini and Gulf-Wyer teams to completely dominate the event.
The Long Tailed Le Mans racer was capable of 0-100km/h in 2.5 seconds and a top speed of 406km/h
The Gulf Team livery 917 was immortalised by Steve McQueen in the 1971 film Le Mans. It has since that time -- along with the Bullit Mustang -- become one of the two most iconic movie cars.
For the 1973 Can-Am series, a turbo-charged version was produced; developing 820kW in race tune and 1180kW in qualifying tune. This version, the 917/30 could accelerate from 0-100km/h in 1.9 seconds and 0-160km/h in 3.9 seconds, hitting a top speed of 414km/h.
Mark Donohue set the land speed record for a closed circuit in a 917/30 at Talladega Sperspeedway in 1975. The average speed was 356 km/h and the record stood for four years.
The Porsche 917 is one of the most significant race cars of all time with current (2009) values at between $3 million to $7 million. If though chassis number 917 – 022 (the primary Steve McQuenn Le Mans film car) came on the market now we expect that that upper limit may be far exceeded.
After Porsche burst onto the racing scene in the early 1950s, the German company had slowly, but gradually progressed through the sportscar racing classes with one goal in mind: an overall victory at Le Mans. Porsche's first success at the legendary 24 Hours race came in 1952, when a 356 took the victory in the 751 - 1100 cc class. Patiently Porsche developed new racing cars like the 550, which still used many parts from the road going Porsche 356. By the mid-1960s the gap between road and racing cars grew bigger and bigger, and with it the racing successes increased as well.
Ford and Ferrari were fighting for the Le Mans victory with very advanced and powerful cars in the mid-1960s. The cars fielded by Porsche were equipped with engines displacing only a fraction of those found in the leading cars. This however did make them more nimble and competitive on tight and curvy tracks. Unfortunately the Le Mans track consisted of long straights, best suited to the most powerful of cars. A rule change at the end of the 1967 season seemed to bring Porsche's new three litre racer, the 908 into contention. The old prototype class was abandoned in favour of a limited production 5-litre Sportscar class (Group 4) and a 3-litre Prototype class (Group 6).
Only two cars were built in sufficient numbers (50) to be homologated for Group 4; the Lola T70 and Ford GT40 Mk I. Both cars were powered by 400+ bhp engines, which was too much for the new 908 to compete with on Le Mans. A JWA / Gulf entered GT40 took the Le Mans win, but chased by two Porsches, victory was closer than ever! A number of manufacturers appealed the new regulations stating that a 50-car production run in one year was too much for a racing car. For 1969 the number was decreased to 25, which opened the door for a number of manufacturers to at least consider designing and building a car to take on the Lolas and Fords.
Decision making time
Under the leadership of Ferdinand Piech, the Porsche racing department had produced a new car almost every year in the mid-1960s. All of them were prototype racers, yet the production reached the now magic figure of 25 almost always, with many cars sold to privateers. Piech figured that if they would build a Group 4 racer, much of the money invested could be earned back from sales to privateers. One of the biggest problems was the enormous and new engine the car would need, especially considering the fact that Porsche's largest engine at the time displaced just under three litres. With little time for testing available, the fact that 25 cars had to be produced before the car could be raced was also a big concern, so the design had to be right straight away.
With less than ten months to go before the 1969 24 Hours of Le Mans race, Porsche set out to design the new car, which represented the single biggest step in their racing history. Porsche's strategy of gradual development had served them very well in the past, but Piech understood more was needed now to finally clinch the overall victory. According to very strong rumours Volkswagen funded approximately 2/3s of the costs of the racing program under the sole condition that Porsche would maintain the use of air-cooled engines for their competition cars. A very interesting way of promoting the air-cooled engine, which Volkswagen used in all of their cars of the day.
The birth of a legend
Weight saving was on the top of the list of the designers and all experience Porsche had gathered on exotic materials was used on the '917' as the new car was to be known. Although the tubular frame was almost identical to that of the 908, it was now constructed of aluminium instead of the steel used on the 8-cylinder racer. The chassis lost some of its rigidity compared to the steel one, but its extremely low weight of just 46 kg more than made up for that. Like all racers of the day, the 917 was suspended all-round by fully independent suspension, made up of wishbones. More exotic materials were found here, with the coil springs used being made up of titanium.
The heart of the 917 was its new engine. The engine used identical cylinders to those found on the 908, just four more, giving a twelve cylinder engine displacing just under 4.5 litres. Two things set the new '912' engine apart from the older engines: the design of the crankshaft and of the camshafts. Whereas the 908 used a boxer type crankshaft, the 912 engine was fitted with a crankshaft similar to those found in 'V'-engines, resulting in a relatively shorter engine. The double overhead camshafts were driven from centrally mounted gears, which effectively cut the engine in two six cylinder sections. A long tradition of shaft driven camshafts was abandoned.
Although the flat-12 was relatively short, it was still a huge engine. In order to stick with the 908's wheelbase, the cockpit was moved forward, giving a somewhat akward driving position. A slightly wider body was fitted compared to the 908, to clear the larger engine and wider track. The rear body featured a detachable tail section, which enabled the customer to choose between a high-downforce or a low-drag tail to suit the needs of the track. The rear wing was fitted with movable flaps, similar to the system used on the longtail 908 coupes. Cold air was blown to the engine by a big fan fitted on top of the flat-12.
Although there were rumours about a large Porsche sportscar being constructed, there was no concrete evidence until the wraps were taken off of the 917 at the 1969 Geneva Motorshow. The stunned press realised a new class of racers was born. There was still a long way to go until the 917 could actually race at Le Mans. When Porsche was first visited by the CSI homologation inspectors three cars were assembled, 18 being assembled and sets of parts for seven more were present. Porsche argued that they could easily build the 25 cars needed, but would then have to take them apart again to prepare the cars for racing. The inspectors refused to homologate the 917 and demanded to see 25 completed cars.
Porsche took the CSI's request very literally and set out to construct 25 cars. In a stunning three weeks the cars were completed, quite an accomplishment considering one engine alone took 160 man-hours of work to be completed. Porsche lined up the completed cars behind the factory for inspection by the CSI. As of April 1st 1969, the 917 was homologated. Ironically the 917's only true competitor, the Ferrari 512 S, was homologated a year later even though only 17 examples were completed when the CSI visited the factory.
What was feared from the outset came through, the Porsche 917 didn't work as well on the racing track as it looked to work on the drawing boards. For some reason the handling was terrible and many thought the 580 bhp engine was too much for the lightweight frame. At its competition debut at the Nürburgring 1000km in April 1969, all works drivers preferred the 908 over the 'unsafe' 917. Longtime Ferrari privateer David Piper was flown in at the last minute to drive the 917, which very carefully driven eventually finished eighth. Porsche searched frantically to figure out what caused the unpredictable and dangerous driving characteristics of the 917.
No solution was found yet, but Porsche persisted reasoning that Le Mans with its long straights would better suit the 917. They were proven partly right, but it was not a 24 Hours race Porsche would like to be reminded of. Again none of the works drivers were willing to risk it all in the 917. Three cars were entered, with the Ahrens/Stommelen 917 qualifying on pole. Disaster struck when one of the 917s crashed out and killed its British driver. The two remaining cars continued and lead the race for a while, but both cars retired. The Ford GT40 again beat the Porsche 908, but by just 2 seconds, the closest margin ever. Much work was needed to fix whatever was wrong with the 917.
For 1970 Porsche decided to leave the running of the 917s to a number of private teams, who would all be fully supported by the factory: Martini Racing, JWA Gulf Racing and Porsche Salzburg. Still franctically looking for the problem that dogged the 917, Porsche together with the private teams were testing the 917 in the fall of 1969. Some of the JWA engineers present were particularly interested in a Porsche 917 Can-Am Spyder also being tested. The short-tailed car seemed to handle a lot better than the regular coupes. The spyder's tail did fit so the engineers picked up a saw and cut off the rear section of the tail. A career changing action!
With the revised tail the JWA 917 changed from a handling nightmare to a pretty well-sorted racing car. Porsche picked up on the British team's golden move and produced a set of new tails for the 917. The rebodied cars are commonly referred to as 917K. At least twenty original 917s were brought up to 917K spec and in 1970 another 12 new 917Ks were constructed. The experiments with the bodies did not stop here and various long-tail variants were tried in 1970 and 1971. The final coupe version was the chunky 917/20 raced at Le Mans in 1971.
Now that the handling was sorted Porsche set out to explore the boundaries of the engine regulations. Ferrari's upcoming contender was going to be fitted with a five litre engine so to be ready for the new challenge a 4.9 litre version of the engine was created by stroking the engine. A lot more torque and 20 bhp were the result of the work. For 1971 a slightly larger bore brought the engine up to 4.998 litre and 630 bhp. For Can-Am racing Porsche developed the most powerful road-racing engine ever, based on the 12 cylinder unit. With two Turbos and a displacement of 5.4 litres this behemoth of an engine produced 1100 bhp in racing trim, with a lot more available for qualifying.