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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 917/30 variant was capable of a 0-62 mph (100 km/h) time of 2.3 seconds, 0–124 mph (200 km/h) in 5.3 seconds, and a top speed of over 240 mph (390 km/h).
There are at least nine variants of the 917. The original version had a medium-long tail with flippers, but had considerable handling problems at high speed because of poor bodywork aerodynamics. The Weyer-Gulf team then experimented with a shorter tail, and solved the aerodynamic and handling problems at testing sessions at the Österreichring, at the expense of some top speed. Porsche adopted these changes into the 917K, which dominated in the 1970 and 1971 World Sportscar Championships. In 1971, a variant of the 917K appeared with an altered tail and shark fins, which together reduced drag and maintained down force. These versions produced around 620 bhp. There were also streamlined versions for Le Mans (1970 917L and 1971 917LH) that were 20 mph faster in a straight line. In 1971 Jo Siffert raced an open-top 917PA Spyder (normally aspirated) in the 1971 CanAm series. There is also the "Pink Pig" aerodynamic research version (917/20), and the turbocharged 917/10 and 917/30 CanAm Spyders. Porsche 917s also raced in the European Interseries in various configurations. In the 1973 Can-Am series, the turbocharged version Porsche 917/30 developed 1,100 bhp (820 kW).
The birth of the 917 
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 three-litre Group 6 prototypes for four years from 1968 through 1971. This capacity reduction would also serve to entice manufacturers who were already building three-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 five-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 Porsche's head of motorsports 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 designed under the leadership of Piëch and Porsche chief engineer Helmuth Bott. 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° flat-12 cylinder 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, some methods were not simple, such as using the tubular frame itself as oil piping to the front oil cooler.
Racing history 
1969-1971 World Sportscar Championship 
In testing, it soon appeared that the Porsche 917 did not work well on the race track. Porsche factory driver Brian Redman recalled 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 1000 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.
Disappointed by the poor results of the 917 in 1969, and facing new competition, Porsche concluded an agreement with John Wyer and his JWA Gulf Team, which became the official Porsche team, and also the official development partner. During tests at the Osterreichring at Zeltweg, works drivers Redman and Ahrens tested the car, and the car still performed like it did before. The Osterreichring was the circuit where the car had won its only race at that time, Wyer's chief engineer John Horsman noticed that the bodywork had a pattern of dead gnats dashed against it, revealing the airflow. The tail was clean—the presence of no dead gnats indicated that the air was not flowing over the tail. A modification to the tail was cobbled-up on the spot in the pits with aluminium sheets taped together. This new short tail gave the 917 much needed stability from downforce. The plastic engine intake cover had already been removed. Redman and Ahrens were doing only one lap at a time before, they each did 10 laps and were satisfied with the improved performance. The new version was called 917K (Kurzheck, or "short").
In addition to the big and powerful 917, the lightweight and compact Porsche 908/3 were developed for the slow and twisty tracks of the Nürburgring and the Sicilian mountain roads used in the Targa Florio, providing wins while the factory-backed 917 remained in the garages, as these cars were not suitable to these tracks. The 908/3 was built to the FIA's 3-litre Group 6 Prototype regulations whereas the 917 was now officially a Group 5 Sports Car following another FIA review of its racing classes, applicable from 1970.
Wyer was surprised to discover that another team was carefully preparing for the 1970 24 Hours of Le Mans with close support from Porsche. As in 1969, the Porsche Salzburg team was a de facto second works team under control of members of the Porsche family. The Martini Racing team also gained some support from Porsche AG; obviously Porsche made efforts to win the race by supporting more than one team.
Also, a new low drag version of the 917 was developed for Le Mans with support from the external consultant Robert Choulet. The 917L (Langheck) featured a spectacular new "Long Tail" body including partially covered rear wheel arches which had very low drag, yet better stability than the 1969 version. A few 4.9-litre engines, introduced at 1000km Monza, were available for some cars, but these proved to put too much strain on the gearboxes.
The favorite team to win, Gulf-backed John Wyer Automotive, lined up three 917Ks, two with the 4.9-litre engine and one with the 4.5-litre unit.
Two 917 L were entered in Le Mans, one in white and red trim by Porsche Salzburg. Driven by Vic Elford and Kurt Ahrens, the pole sitter's 4.9-litre engine failed after 225 laps. Both drivers had also been entered on the team's other car, a red and white 917 K with the standard 4.5-litre engine, qualified by Hans Herrmann and Richard Attwood on rather low 15th spot, but they did not drive after their own car failed.
The other L was entered by Martini Racing, qualified by Willy Kauhsen and Gérard Larrousse on 12th position. The spectacular livery of this car was an elaborate whirls and swoops of light green on a dark blue background. The car with the regular engine gained the nickname of the Hippie Car or the Psychedelic Porsche from the team and media.
Early in the race, most of the works Ferrari 512 entrants eliminated each other in a shunt. The two Porsche factory teams, Gulf-Wyer and Porsche Salzburg, continued to battle each other, but all Wyer cars were out after 12 hours. At the end it was the red and white #23 917K of Porsche Salzburg, with the standard 4.5-litre engine, carefully driven by Stuttgart's own Hans Herrmann and Englishman Richard Attwood through the pouring rain, that finally scored the first overall win at Le Mans, in a wet race that saw only 7 ranked finishers. Martini's blue 917L with a green "psychedelic Hippie" design came in 2nd. Both cars were later paraded across Stuttgart. To complete Porsche's triumph, a 908 came third, a 914 sixth, and a 911S seventh, beaten only by two Ferrari 512.
Towards the end of the 1970 season, Ferrari entered some races with a new version of the 512, the 512M (Modificata). The 512M had a new bodywork built on the same aerodynamic doctrine as the Porsche 917K. At the end of 1970 the 512M was as fast as the 917s. but still lacked in reliability.
During the 1970 season the FIA announced that Group 5 Sports Cars would be limited to a 3-litre engine capacity maximum for the newly renamed World Championship of Makes in 1972, so the big 917s and 512s would have to retire from the championship at the end 1971. Surprisingly, Ferrari decided to give up any official effort with the 512 in order to prepare for the 1972 season. A new prototype, the 312 PB, was presented and entered by the factory in several races. But many 512s were still raced by private teams, most of them converted to M specification.
By the end of 1970, Porsche had stamped their authority on endurance racing by convincingly dominating the championship that year. Of the 10 races in the championship (plus some other non-championship events), the works teams (John Wyer Automotive and Porsche Salzburg) had won every race except Sebring (which was won by Ferrari) that year with the 2 makes of cars they used, the 917K and the 908/03; with the 917K winning 7 of 8 events it was entered in; and the 908/03 winning at the Targa Florio and the Nürburgring (the 917K was not entered by the works teams at these 2 events). Still having some of their 25 cars remaining unsold, Ferrari offered them to customers at a bargain price - a move that had hardly been imaginable less than two years previously. For Porsche, the original production series of 25 917s could not satisfy demand. Over 50 chassis were built in total. An underdog for 20 years, Porsche had turned itself into the new leader of sports car racing with the 917.
The domination of Gulf-Wyer and Martini Porsches in 1971 was overwhelming. The only potential challenger to the 917 appeared early in the season: Roger Penske had bought a used 512S chassis that was totally dismantled and rebuilt beyond M specification. The car was specially tuned for long races, receiving many unique features among which were a large rear wing and an aviation-inspired quick refueling system. The engine was tuned by Can-Am V8 specialist Traco and able to deliver more than 600 hp (450 kW). Penske's initiative was not backed by Ferrari works. This 512M, painted in a blue and yellow livery, was sponsored by Sunoco and the Philadelphia Ferrari dealer Kirk F. White. Driven by Penske's lead driver Mark Donohue, it made the pole position for the 24 Hours of Daytona and finished third despite an accident that required almost an hour in the pits. For the 12 Hours of Sebring the "Sunoco" made the pole but finished the race at the sixth position after making contact with Pedro Rodríguez's 917. Despite being fastest on track on a few occasions, the 512M was not a serious contender.
The presence of the 512M "Sunoco", as well as the Alfa Romeo T33/3 which won Brands Hatch, the Targa Florio and Watkins Glen, forced Porsche to pursue their efforts in research and development: tails of the 917K and the 908/3 were modified with vertical fins, and the 917 LH aerodynamics received further improvements. New chassis made of magnesium were developed, even though this material could burn vigorously in the instance of a fire.
A heavily modified car, the 917/20, was built as test-bed for future Can-Am parts and aerodynamic "low-drag" concepts. The 917/20 which had won the test race at Le Mans was painted in pink for the 24 hours race, with names of cuts of meat written in German across it in a similar fashion to a butcher's carcass diagram, earning it the nickname "Der Truffeljäger von Zuffenhausen" (The Truffelhunter of Zuffenhausen) or just plain "Pink Pig".
And at Le Mans, once again it was not the new machinery that won. The white #22 Martini-entered 917K (chassis number 053) of Helmut Marko and Gijs van Lennep, equipped with a magnesium frame, set an overall distance record that stood until the 2010 win by the Audi R15 TDI of Romain Dumas, Mike Rockenfeller and Timo Bernhard when they set a distance record of 5,335.313 km (3,315.210 mi) at an average speed of 220.2 km/h (137.6 mph). This Porsche still holds the fastest lap at the Le Mans racing circuit to this day but of course, there have been a number of fundamental changes to the circuit since 1971.
1972–1973 Can-Am 
As the new rules for the 3-litre prototypes were not favourable to their existing low-weight, low-power Porsche 908, Porsche decided against developing a new high power engine that could keep up with the F1 designs of the competition's — at least in naturally aspirated form. In 1976 they would return to sport-prototype racing with the turbocharged Porsche 936 racecars after the engines were tested in Porsche 911 versions.
After their successes with the 917 mainly in Europe, Porsche instead decided to focus on the North American markets and the Can-Am Challenge. For that series, larger and more powerful engines were needed. Although a 16-cylinder engine with about 750 hp (560 kW) was tested, a turbocharged 12-cylinder engine with comparable power output was ultimately used. The 917 chassis also had to be lengthened to accept the longer 16-cylinder engine, and drivers complained that this longer chassis did not handle as well.
The turbocharged 850 hp (630 kW) 917/10 entered by Penske Racing won the 1972 series with George Follmer, after a testing accident sidelined primary driver Mark Donohue. This broke the five-year stranglehold McLaren had on the series. The further evolution of the 917, the 917/30 with revised aerodynamics, a longer wheelbase and an even stronger 5.4-litre engine with up to 1,580 horsepower (1,180 kW) won the 1973 edition winning all races but two when Charlie Kemp won the Mosport race and George Follmer won Road Atlanta and Mark Donohue won the rest. Most of the opposition was made of private 917/10 as McLaren, unable to compete against the 917 turbos, had already left the series to concentrate on Formula 1 and the Indy 500.
The 917's domination, the oil crisis, and fiery tragedies like Roger Williamson's in Zandvoort pushed the SCCA to introduce a 3 miles per U.S. gallon maximum fuel consumption rule for 1974. Due to this change, the Penske 917/30 competed in only one race in 1974, and some customers retrofitted their 917/10 with naturally aspirated engines.
The 917/30 was the most powerful sports car racer ever built and raced. The 5.374-litre 12 cylinder (90.0 x 70.4 mm) twin-turbocharged engine could produce 1,580 bhp (1,180 kW) in qualifying tune, with twin turbochargers run up to full boost, 39 psi (2.7 bar), though it usually raced with around 1,100 bhp (820 kW) at 7,800 rpm to preserve the engine. Weighing 1,800 lb (820 kg), giving it a power to weight of 1967.36 bhp/tonne in qualifying tune and 1369.68 bhp/tonne in race tune. The 917/30 dominated the Can-Am series during the 1973 season. The 917/30 could go from 0-62 mph (100 km/h) in 1.9 seconds, 0-100 mph (160 km/h) in 3.9 seconds, 0-200 mph (320 km/h) in 10.9 seconds, and on to a top speed of more than 260 mph (420 km/h). The high-level of performance and attendant fuel consumption of the engines, and ever increasing risk, has led to the 917/30 sometimes being cited as the car that killed Can-Am racing. The 917 was also the only championship winning car in Can Am not to be powered by Chevrolet.
In 1981, it appeared that new Le Mans regulations would allow a 917 to race again. The Kremer Racing team entered a homebuilt updated 917, the 917 K-81.
The car raced at Le Mans qualifying in the top 10 but retired after seven hours after a collision with a back marker led to a loss of oil and withdrawal.
The final chapter though was to be at Brands Hatch where the car ran in the 6 hours at the end of the season. The car was competitive and ran at or near the front, including a spell in the lead until a suspension failure led to retirement.
Other uses 
On 9 August 1975, Porsche and Penske would give the Can-Am car its final send off in style, when they took their 917/30 to Talladega to break the FIA speed record on a closed circuit. With Mark Donohue driving, the average speed reached was 221.160 mph (355.923 km/h). As well as being the last official outing for the 917, it was the last major accomplishment for Donohue before his fatal accident in practice for the Austrian Grand Prix a week later. The record would stand until 1980.
Several 917 coupés as well as 917/10s (powered by turbos or NA engines) were run in Europe's Interserie until the mid-1970s.
Many 917 leftover parts, especially chassis, suspension and brake components, would be used to build the Porsche 936 in 1976.
Despite the car's impracticality, at least two 917s were road-registered:
Count Rossi of the Martini company, bought chassis 030 from Porsche. He raced it once under the Martini Racing Team Flag at the Zeltweg 1000 km World Championship race on 27 June 1971. After the race, it was returned to the factory, where it was modified with basic road equipment (exterior mirrors, turn signals, exhaust system and comfort modifications) and painted silver. None of the European authorities would certify the car for road use and Rossi obtained the Alabama plate 61-27737 to circumvent the problems.
The second, for Joachim Grossmann, was painted white and given the German registration CW-K 917. The Danish car magazine Bilen in a 1977 article details how Grossmann bought the frame and other components of the original Chassis 021 which had crashed badly at Le Mans in 1970 for 20,000 DM, rebuilt it and then modified it (examples: turn signals, hand brake, Safety glass windows and some modifications to the exhaust system) to satisfy German safety inspectors leading to the registration. Grossmann's car is not officially Chassis 021 because other parts from the 1970 wreck at Le Mans were mated to spare frame components and retained the Chassis 021 designation.
In 1970, Hot Wheels released a Porsche 917 with some different designs.
A red 917/10k of unknown origin was used in the 1981 film 'The Last Chase'.
- Lyons, Pete (1995). Can-Am. Osceola, Wisconsin: Motorbooks International. p. 223. ISBN 0-7603-0017-8.
- Melissen, Woulter. "Porsche 917 PA Spyder". www.ultimatecarpage.com. Retrieved 26 December 2012.
- "Porsche 917 celebrates 40th birthday". AUSmotive.com. Retrieved 2010-11-28.
- Appendix J 1969, Art. 251, Art. 252 on www.fia.com
- Porsche 917 History - 1969 Season (Part 1) on www.porsche917.com.ar
- Simanaitis, Dennis (November 2012). "1972 Porsche L&M 917/10 Spyder". Sports Car Market 24 (11): 52.
- Wouter Melissen (9 September 2009). "Porsche 917". ultimatecarpage.com. Retrieved February 28, 2011.
- Ed Foster (2010-02-19). "February's audio podcast (part 2) with Brian Redman - F1 History". Motor Sport Magazine. Retrieved 2012-06-06.
- "Porsche Celebrates 40 Years of Its Ground-Breaking 917 Race Car - Wide Open Throttle - Motor Trend Magazine". Wot.motortrend.com. Retrieved 2010-11-28.
- Fastest races and laps ever on 8w.forix.com
- Street legal Porsche 917[dead link]
- "Original "Project 917" Web Page". Project917.com. Retrieved 2012-06-06.
- "Kraftwerkz presents The LMK917 Porsche 917 Replica". Kraftwerkz.net. Retrieved 2010-11-28.
- "Race-Car Replicas 917". Race-car-replicas.com. Retrieved 2010-11-28.
- "Home of Elite Enterprises, Inc Vehicles". Laser917.net. 2005-08-25. Retrieved 2010-11-28.
Further reading 
- 1972 – The Making of a Winner: The Porsche 917 by Larry Pihera (ISBN 0-397-00807-4)
- 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)
|Wikimedia Commons has media related to: Porsche 917|
- 1970 Porsche Kurzheck Coupe (Official Porsche Website)
- 1971 Porsche Kurzheck Coupe (Official Porsche Website)
- 1973 Porsche 917/30 Spyder (Official Porsche Website)