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The Porsche 917 is a race car 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 Can-Am 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 test track top speed of up to 240 mph (390 km/h).[better source needed] The highest official speed ever clocked for a 917 at Le Mans is 362 km/h or 224.4 mph.
There are at least eleven variants of the 917. The original version had a removable long tail/medium tail with active rear wing flaps, but had considerable handling problems at high speed because of significant rear lift. The handling problems were investigated at a joint test at the Österreichring by the factory engineers and their new race team partners John Wyer Engineering and after exhaustive experimentation by both groups, a shorter, more upswept tail was found to give the car more aerodynamic stability at speed. The changes were quickly adopted into a new version of the 917, called the Kurzheck, or short-tail, with the new version being called the 917K. The 917K, and the special Le Mans long-tail version (called the 917 Langheck, or 917L), dominated the 1970 and 1971 World Sportscar Championships. In 1971, a variant of the 917K appeared with a less upswept tail and vertical fins, and featured the concave rear deck that had proved so effective on the 1970 version of the 917L (see below). The fins kept the clean downforce inducing air on the top of the tail and allowed the angle of the deck to be reduced, reducing the drag in direct proportion. The result was a more attractive looking car that maintained down force for less drag and higher top speed. By this time the original 4.5-litre engine, which had produced around 520 bhp in 1969, had been enlarged through 4.9-litres (600 bhp) to 5-litres and produced a maximum of 630 bhp. The 917K models were generally used for the shorter road courses such as Sebring, Brands Hatch, Monza and Spa-Francorchamps. The big prize for Porsche however, was Le Mans. For the French circuit's long, high speed straights, the factory developed special long tail bodywork that was designed for minimum drag and thus highest maximum speed. On the car's debut in 1969, these long-tail (917L) models proved to be nearly uncontrollable as there was so little down force. In fact, they generated aerodynamic lift at the highest speeds. For 1970, an improved version was raced by the factory (although the John Wyer team still preferred the security of the 917K) and for 1971, after very significant development in the wind tunnel, the definitive 917L was raced by both factory and JW. These cars were so stable that the drivers could take their hands off the steering wheel at speeds which reached 246 mph. 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).
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 seven-litre Ford GT40 Mk.IV and four-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 minimum production figure to compete in the sport category of the International Championship of Makes (later the World Sportscar Championship) was reduced from 50 to 25, starting in 1969 through the planned end of the rules in 1971. With Ferrari absent in 1968, mainly Porsche 908s and Ford P68s were entered there, with the Ford being a total failure. As a result, old 2.2-litre Porsche 907s 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 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 No. 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 by chief engineer Hans Mezger under the leadership of Ferdinand Piëch and 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 Mezger, which was a combination of 2 of Porsche's 2.25L flat-6 engines used in previous racing cars. 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. It was Porsche’s first 12-cylinder engine and used 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.
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 although 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 #14 917 led early, but succumbed to an oil leak, while the #12 dropped out of the lead and the race in the 21st hour with a broken gearbox, despite leading by nearly 50 miles. 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).
In June 1969, Enzo Ferrari 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 Österreichring at Zeltweg, works drivers Redman and Ahrens tested the car, and the car still performed like it did before. The Österreichring 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 lack of 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 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 tail").
In addition to the heavier 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 for 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 works team under control of members of the Porsche family. The Martini Racing team also gained 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 917LH (Langheck) featured a spectacular new long tail body which had very low drag, yet more rear downforce than the 1969 long tail. A 4.9-litre engine, introduced at 1000km Monza, was available but these proved to be unreliable for longer distance races.
The 917 did not compete at all the races of the season, however. Porsche's previous competition model, the 908, was redesigned with an all-new chassis and designated 908/03 so it would be used at the Targa Florio and Nurburgring 1000km events- two twisty, narrow and slow tracks the 917 was not competitive at. Vic Elford drove a 917 during practice for the 1970 Targa Florio and it proved to be so physically demanding and difficult to drive around the circuit that he had to be lifted out of the car, although he set the 5th fastest time. The 908/03 was very effective at these two races. Porsche's dedication was such that they were building cars for each type of track- the 908/03 for the slow, twisty tracks, the 917K for the medium and high-speed tracks, and the 917L for the fast straights of Le Mans.
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 LH 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 dropped an inlet valve after 225 laps. Both drivers had also been entered on the team's other car, a red and white 917 K with the 4.5-litre engine, qualified by Hans Herrmann and Richard Attwood in rather low 15th spot, but they did not drive after their own car failed.
The other LH 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 4.5L 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 917LH came in 2nd. Both cars were later paraded across Stuttgart. In addition to Porsche's triumphant 1, 2 victory, a Porsche 908 came in third overall, a Porsche 914-6 came in sixth overall (plus it won the GT class), and a Porsche 911S was seventh. (Two Ferrari 512s took fourth and fifth place overall.)
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 a similar 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 dismantled and rebuilt beyond M specification. The car was specially tuned for long races, receiving many unique features among which were a larger 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 Trüffeljäger von Zuffenhausen" (The Truffelhunter of Zuffenhausen) or just plain "Pink Pig". This experimental car surprisingly qualified 7th for its only race- the 1971 Le Mans 24 Hours, but during the night Reinhold Joest crashed the car after its brakes failed. This was because the 917/20 was harder on the brakes than the K, but ran to the same brake change schedule.
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 2010 when the Audi R15 TDI of Romain Dumas, Mike Rockenfeller and Timo Bernhard set a distance record of 5,335.313 km (3,315.210 mi), 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.
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-based engine designs of the competition — at least in naturally aspirated form. In 1976 they would return to sport-prototype racing with the turbocharged Porsche 936 race cars 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) 917/10K 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 917/10K 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 917/10K 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 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.
There were a number of versions of Porsche 917 made over the years; at least eleven different versions have existed.
1969 917: This was the original Porsche 917 made by Porsche from 1968 to 1969 to comply with the CSI rules about entering a car in the World Sportscar Championship. This car was first run at Le Mans and had considerable handling problems due to aerodynamic lift. The original specification of the car included a detachable long-tail (Langheck), that was designed using experience from the previous 907 long-tail coupes for minimum aerodynamic drag (with suspension controlled moving flaps). A short-tail version was run at the 1969 Nurburgring 1000 km, which had no moving flaps and a full-width rear spoiler. None of the early specification 917s are known to have survived with this bodywork - all being converted at a later stage to the vastly improved 1970-spec Kurzheck or Langheck specifications. One 917L is known to have been destroyed (917L-005 - J.Woolfe) at Le Mans and one or two others simply location unknown although many suspect some were scrapped by the factory as being 'tired chassis' with new replacements being built when needed by customers.
1969 917PA (Porsche-Audi): This car was an open topped and short-tailed version of the original 917 and was made to be raced in the Can-Am championship. It was raced by Swiss Jo Siffert without much success. The 917PA's gently upswept tail was one of the catalysts that led to the later aerodynamic breakthrough with the aerodynamics of the 917 coupe. In early 1970, in an attempt to increase power and keep up with other more powerful cars in the Can-Am championship, an experimental 7.2-liter, 850 bhp flat-16 engine was tested. This was tested in the 917PA, but because it was 80 kg heavier than the existing 12-cylinder engine and had a 270mm longer wheelbase, its handling was completely compromised. The 16 was never raced.
1970 917K (Kurzheck, German for "short tail"): The 917K was an evolution of the original 1969 car. After the first 917s were run in 1969, it was clear the car's aerodynamics made it nearly undriveable at higher speeds. After the 1969 championship season had finished, John Wyer requested a 3-day test session at the Austrian Österreichring (Zeltweg) course. The Porsche technical team turned out ready to do some serious panelwork on the coupe and in order to make a comparison, brought along the Can-Am 917PA Spyder. The drivers present instantly preferred the PA and together, the JW and Porsche engineers came up with the idea of a more upswept tail (as on the 917PA). It must also be noted that the JW team had had similar high speed handling problems with the early Ford GT40 models. With gaffer tape and aluminium sheet a completely new short tail was evolved at the racetrack. This was quickly converted into a 'production' design back at Porsche and the 917K (Kurzheck) made its public debut at the 1970 season opening Daytona 24 Hours. Such was the improvement in the stability of the car at high speed, the 917K became the standard configuration for all races except Le Mans. This car was raced at every event by the two factory-supported teams (John Wyer Automotive and Porsche Salzburg) in the 1970 season except the Targa Florio and the Nürburgring 1000 km. The smaller, more nimble and generally better suited 908/03s were used for those races. The 917K won 7 out of 10 races; all the races it competed in. Later on in the 1970 season, the 4.5 liter flat-12 was bored out to 4.9 liters, then 5 liters.
1970 917L (Langheck, German for "long tail"): This longtail, low drag version of the 1969 917L was purpose-built for the 1970 Le Mans 24 Hours. Le Mans in 1970 was almost entirely made up of long straights and this version was designed to maximise the speed capability resulting from the increased power developed by the flat-12 engine over the previous Porsche types. The 1970 917L was significantly developed from the initial 1969 car. Nevertheless, factory driver Vic Elford had found the car's ultimate speed an advantage enough over its still questionable handling in the braking and cornering sections of Le Mans. It was 25 mph faster down the straights than the 917K and the Ferrari 512Ss. Two were raced in the 1970 Le Mans race, one was entered by Porsche Salzburg (SER#917L 042) (White/Red Shell livery) and another was entered by Martini International, (SER#917L 043) painted in psychedelic colors. The Porsche Salzburg 917L was qualified in pole position by Vic Elford, but this car retired with engine failure after 18 hours and the Martini 917L finished 2nd, 5 laps behind the winning Salzburg 917K of Hans Herrmann and Richard Attwood. Le Mans was the only race in which the 917Ls competed in that year. Of the two, only the Martini car (917L-043)is known to exist outside the factory collection: it is on display at the Simeone museum in Philadelphia. There was a major longtail crash during testing in 1970 at the VW test track near Wolfsburg, involving Kurt Ahrens in chassis 917L-006/040. A total of six 917L models were built and used between the 1970 and 1971 season(040-041-042-043-044*-045). *Unused spare chassis reportedly swapped for 043's. (No documentation)
1971 917K: The 917K was further developed for the 1971 season, and the car had vertical fins and 2 airboxes on the tail section for better aerodynamics and cooling. The fins retained the airflow over the rear part of the bodywork, allowing the deck height to be reduced for a given level of downforce. As a result, the 'finned' 1971 917Ks were faster than the 1970 versions. This version proved as successful as the preceding 1970 version. TA version of this model won Le Mans in 1971; but it had a specially-built (lighter) magnesium tube-frame chassis (whereas all the other 917Ks had an aluminum tube-frame chassis).
1971 917LH* (Langheck, German for "long tail"): The 1971 model was a further development of the 1970 917LH and was also made specifically to compete in only one race: the 1971 Le Mans 24 Hours. The car was also more stable than its 1970 predecessor because of new bodywork and revised suspension set ups and partially enclosed rear wheels covers. The front section was also redesigned. The three LHs were run at Le Mans in 1971: two were run by John Wyer's team (SER#917L-043 and 917L-045) (Both Gulf livery) and one was run by the Martini International team, (SER#917L-042) (Silver Martini Racing livery). Although Jackie Oliver qualified one of the Wyer 917LHs on pole position, none of the three cars finished the race. This was the last race in which the 917LHs were run in. Only three 917Ls survive and each is on display in a museum: 917L-042 is on display at the Porsche museum in Stuttgart, 917L-043 is on display at the Simeone Foundation Automotive Museum in Philadelphia, PA and 917L-045 displayed at the Le Mans museum. 045 was repainted like 042 and they are now both painted in identical 1971 Martini colours. Chassis 043 ( 044 ), which is now in the Simeone Foundation Automotive Museum, was restored to its 1970 Martini 'hippie' colours prior to its sale in the 1998 Christie's Pebble Beach auction. * LH is non-factory term used here but is generally accepted by most to describe the 'rework' for the 1971 season of the previous 1970 L models.
1971 917 Interserie Spyder: Of the three Porsche 917 Interserie built for use in the German Interserie championship, two were converted over from two Porsche 917PAs and one was rebuilt from a 917K that was crashed by motorcycle ace Mike Hailwood during Le Mans in 1970. These cars were very successful in that series of racing, winning the 1971 championship..
1971 917/10: This development of the 917PA was run in the North American Can-Am championship and was driven by Jo Siffert. It was moderately successful; Siffert was shut out of the top 3 points positions for that season.
1971 917/20: This variant was a one-off experimental research and development (R&D) car. It was made as an intermediate car to combine the low drag of the LH and the stability of the K. It was only raced once, at Le Mans in 1971 where it was entered by the Martini International team and driven by Germans Reinhold Joest and Willi Kauhsen. This variant was known as "Pink Pig" for its broad proportions and pink livery with meat cuts running over the bodywork. Although it qualified seventh, it retired from the race after a heavy accident while Joest was driving. The car still exists and after being restored, it is on display at the Porsche Museum in Stuttgart.
1972 917/10: This car was Porsche's first full-hearted attempt at Can-Am in 1972; new WSC regulations only allowing prototypes with engines up to 3 liters rendered the 917's obsolete for that series. This car ran the 5-liter Flat-12 and was modified to accommodate additional compression; two turbochargers were added to give the car tremendous horsepower. George Follmer won the Can-Am championship that year. Twelve of these cars still exist.
1973 917/30: This variant, the final official reiteration of the 917, is perhaps the most powerful sports racing car to have ever existed. With all new bodywork and the twin turbocharged engine being bored out to 5.4 liters giving it 1100–1580 horsepower, depending on boost. These cars were so unbeatable that it was known for killing the Can-Am series's popularity in the United States. Six still exist, (one is a new build from parts).
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 Gregorio Rossi de Montelera 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 in 1975 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.
Aurora slot cars released some of these Porsche 917's in their AFX line-up, replicated to their original colors and markings. They were widely available in the early to mid-70's and were raced completely stock.
A replica of a 917/10 was used in the 1981 film 'The Last Chase'.
917-001 Test car, now in Porsche Museum (painted as 1970 Le Mans winner).
917-002 Test chassis, scrapped.
917-003 Test chassis, then T-car at Spa 1969. Scrapped after accident.
917-004 John Wyer then rebuilt after crash at Brands Hatch 1970 using 017. This car has been bought by xxxxx in 1975, re-sold in 2004 and finally found its way to a car dealer in 2011 who restored it to original condition. The 917-004 went on sale on JamesEdition in 2017 for an speculative amount north of US$ 10 million. 
917-005 Le Mans 1969 - destroyed
917-006 Roller endurance test, scrapped.
917-007 Rebuilt as spyder in 1971
917-008 Roller endurance test in 1970, scrapped.
917-009 Scrapped after Sebring 1971
917-010 Sold to David Piper 1969
917-011 Written off while testing at Targa Florio 1970.
917-012 1969 scrapped after tests or allegedly used as a spare frame for 917-021.
917-013 Used for Le Mans film and crashed by David Piper. Rebuilt with 034 parts, but kept number 013 (according to the owner, who bought the car from the Porsche factory at the end of the 1973 season).
917-014 Rebuilt in 1971 using chassis 029.
917-015 A new chassis 035 became 015 in 1971 and it has been rebuilt as a Spyder for Interserie 1971 with chassis 917-01-021. In 2000 car was restored in its original Daytona 1970 configuration and Gulf colors by Gunnar Racing. But 917-01-021 was re-created using the original roll bar and rear section of the chassis while about 80% of the Spyder chassis was new.
917-016 Sold to Chris McAllister of Indianapolis, IN in 1996 and currently competes in historic racing.
917-017 Rebuild of 004, carrying number 004. Used in 1970-71 and was restored by Gunnar Racing in 2014 by its owner, Kevin Jeanette.
917-018 Sold to Chuck Stoddard in 1975
917-019 Sold to Miles Collier in 1998 and currently on display at the Revs Institute for Automotive Research in Naples, FL.
917-020 In 2000 restored in its Martini 1971 colors.
917-021 Crashed at Le Mans. Allegedly rebuilt using chassis 917-012 (reissued as 917-021 so this can be considered a 917-012/021), old 021 damaged frame was probably sold in 1973 with bodywork but no engine to Manfred Freisinger (Porsche spares dealer), then sold to Joachim Grossmann in 1975 and restored/converted as a road legal vehicle (plate CW-K 917) in 1977, sold to Don Marsh in 1983 and converted back to race spec (maintaining some road legal features like indicators), sold to Bobby Rahal in 2002, sold to Juan Barzi in 2003.
917-01-021 Spyder built using chassis 015. Gunnar Racing restored 917-015 from 917-01-021 in 1999-2000, but re-created 917-01-021 using the original roll bar and rear section of the chassis. All of the original suspension, engine, gearbox and bodywork from the spyder have been used though.
917-022 Le Mans film car, Auto Usdau 1971. Originally purchased by Steve McQueen's Solar Productions for the movie "Le Mans." After filming the car ran a couple of races and was briefly owned by Brian Redman, who then sold it to Richard Attwood. Frank Gallogly purchased in 2000 via RM Auction, Monterey who then sold to Jerry Seinfeld in 2002. Limited use in competition.
917-023 1970 24H Le Mans 1st no.23 (Hermann/Attwood). Wearing incorrect paint and secluded in Japan's famous Matsuda Collection since the early-1980s, this car has been returned to its proper Salzburg red and white livery (2000). Collection Monteverde (2014)
917-024-2 Was originally sold to Jo Siffert in 1970 from Porsche AG. Was leased to Solar Productions and used for Le Mans film under the #22. No race history. Sold in 2002 to Audemars Piguet and stored in Germany at RWTH Aachen University.
917-025 Was formerly 917-024, but was changed to 025 after a restoration by Kevin Jeanette in 2004. Was sold to Peter Vögele of Switzerland in 2005; competes in historic racing.
917-026 Crashed by Hailwood at Le Mans. Rebuilt using chassis 031. Original crashed chassis repaired and rebuild as Spyder for Uschi Heckersbruch driven by Neuhaus in 1971.
917-027 917 PA Prototype 917PA. Test chassis.
917-028 917 PA Given 917/10 body for CanAm 1973.
917-029 Spare frame, used for 014.
917-030 Sold to Count Gregorio Rossi de Montelera as a road car (American plate 61-27737), currently (2014) registered to Manfredo Rossi di Montelera (Gregorio's son)
917-031 Spare frame, used to rebuilt 026, used by John Wyer 1970-71. Possibly converted to spider for Ernst Kraus.
917-032 Spare frame, scrapped after tests
917-033 Sold in Germany. Never used
917-034 Spare frame, used to repair 013.
917-035 Spare frame, used for 917-015
917-036 Car sold without engine. Never raced
917-040 LH Coupe test car using parts of 917-006. Scrapped after bad accident, completely destroyed.
917-041 LH Coupe Le Mans tests 1970 with Linge, car n°21. Hockenheim test run with Kauhsen, damaged by Kauhsen at Ehra track test. Dismantled for inspection. 1972 Freisinger Motorsport. 1980 sold to Guy Chasseuil, Sonauto. 1992 sold to Olivier Boyadjian, Paris, France.
917-042 LH Coupe now in Porsche Museum.
917-043 LH Coupe, June 1970 Hockenheim Test (Elford/Kauhsen) and 24H Le Mans (Larousse/Kauhsen no.3 "Hippie". Crashed by Siffert at Hockenheim in November. Chassis scrapped, December 1970. Components used for 917/10-002 and 917-044.
917-044 LH Coupe, April 1970 reserve tubular frame and long tail body. 1971 components 043 used for 044. Chassis 044 renumbered as 043 (for Carnet de Passage reason), 1971 Le Mans Test (Oliver/Van Lennep/Siffert) and 24H Le Mans in June no. 18 GULF-racing (Rodriguez/Oliver), after Le Mans chassis renumbered as 044; car disassembled, chassis 044, an original long tail body and an engine sold to Vasek Polak, now in Simeone Foundation Automotive Museum in Philadelphia (in Martini Psychedelic livery).
917-045 LH Coupe now in Le Mans museum, painted as 041 (Silver Martini livery), previously in Gulf livery
917-051 Magnesium chassis; scrapped after tests
917-052 Magnesium chassis; scrapped after tests
917-053 Magnesium chassis; owned by Porsche AG and on display at Porsche Museum. 1971 24H Le Mans 1st no.22 (Marko/Van Lennep)
In 1969-71 were 43 naturally aspirated cars built (36 K, 5 LH and 2 Spyders) and 16 Turbo (13 917/10 and 3 917/30). Chassis 037, 038, 039, 046 - 050 weren't built, for a total of 59 917s built:
917/10-001 Prototype, development car, in 1971. Sold to Willi Kauhsen in 1972, sold in 2008 to Ulrich Schumacher, 2012 sold to Claudio Roddaro
917/10-002, 1st cusomer Spyder deliver new to Jo SIFFERT, sold in 1972 to W. Kauhsen, sold in 1999 to John McCaw Collection, 2008 sold to Dr. Ulrich Schumacher, 2012 sold to Claudio Roddaro
917/10-003 Originally part of the Vasek Polak collection since 1974. Sold in 1998 to John McCaw and was used in historic racing in the US. Later sold again in 2012 for $5.5 million to an unknown buyer (possibly Bruce Canepa).
917/10-004 Was raced at Zolder and at the Nürburgring in the 1980s. In 1985 driver Hans-Dieter Blatzheim was killed in an accident during private testing for the Supersports race at the Nürburgring. In 1992 the car was sold to Jobst Heemeyer of Bremen, Germany.
917/10-005 Owned by Porsche AG and has been displayed in museums for its entire life. Permanently exhibited in Leipzig Porsche Museum.
917/10-006 Originally part of the Vasek Polak collection since 1974. Sold in 1991 to Jobst Heemeyer in Germany.
917/10-007 Purchased by Brumos Racing/Peter Gregg in 1974 and was raced off and on until 1991 when it was sold to Vasek Polak. It was sold back to Brumos in 1997 where it has remained ever since. Since then it has competed in numerous historic sports car races.
917/10-008 Was once owned by Carl Thompson but was then sold in 2006 to Manfred Freisinger of Freising Motorsport where it received a complete restoration. Was raced a few times in 2008 in Europe.
917/10-010 Test magnesium chassis. Scrapped
917/10-011 Scrapped after Donohue's accident during test.
917/10-015 Has been in the hands of private collectors since 1977. Currently owned by William "Chip" Connor since 2006. It appears the car was then restored. Most recently it was showcased at Pebble Beach in 2010 in Bosch livery.
917/10-016 Ernst Kraus purchased this car new in 1973. In 1976 it was purchased by Vasek Polak and brought to the US. Vasek would later sell the car to Ottokar Jacobs in 1998, where it has been campaigned heavily in historic racing ever since.
917/10-017 George Loos originally purchased and raced this car from 1973-76. It then remained in storage until 1991 when it was purchased by Group Convector of Sweden. It was then sold to Bruce Canepa in 1998 where it has been involved in historic sports car racing at various tracks in the USA.
917/10-018 Vasek Polak was the first owner of this car and was raced in Can-AM. Hurley Haywood and George Follmer would later race this car in 1982 at the Monterey Historics. The car was later sold by RM Auctions in 1999 to Jody Scheckter.
917/20-001 'The Pink Pig' Le Mans 1971. Now in Porsche Museum (since 1997)
917K81 the 1981 Kremer version of the 917K
917/30-001 Original Can-Am test chassis with adjustable frame and wheelbase – built to ’73 “Spyder” spec. Periodicals describe this car as a type “917/20TC” dubbed so because of the use of a 917/30 front section mated to a 917/10 rear section. Was tested with Mark Donohue from 72-73 and later raced by Herbert Müller in 1974-75 Interserie in Martini colours. In 1975 it was rebuilt & painted green for Vaillant Racing. In 1976 this car was retired. It is now with Porsche AG where it has been almost exclusively stored at the Porsche Museum ever since.
917/30-002 Another car that was built to ’73 “Can-Am” Spyder “Lang Heck” spec for Sunoco/Penske Racing Team. This was the first T car and was raced for part of the 73 season in Can-Am competition by Mark Donohue until it was badly damaged in an incident with Mark behind the wheel at the Watkins Glen event. Penske rebuilt the car where it served as a spare car for the remainder of the season. In 1974, it was retired back to Porsche AG. Since then it has resided at the Porsche Museum and has been raced at Goodwood by Derek Bell and Jochen Mass several times. The car has also had several appearances at historic events all over Europe.
917/30-003 Another one of the 73 "Lang Heck" cars for Penske, Mark Donohue saw much success in this car-winning the 1973 Can-Am Championship. In 1974, Brian Redman raced this car at Mid-Ohio where he would finish in 2nd place. Donohue would later pilot the 003 at Talladega Super-speedway where he would set a closed-course world record at 221.160 mph. Porsche AG would later sell this car to Otis Chandler of the LA Times in 1976. A few years later in 1983 it was sold to Jack Setton. It would later be restored in 2002 where it remains in the Jack Setton Collection.
917/30-004 Parts Car. Build started in 1973 as a 1974 Penske team chassis, and the primary car for Mark Donohue. However the build was suspended because of rule changes, but completed by Porsche before being sold in 1978 to Alan Hamilton of Australia. The car was white. Then it was offered up for sale in 1983 and then again in 1991 where it was purchased by Porsche AG for $2.25 million. Later it was painted in the Sunoco livery and then sold in 1994 to David Morse where it was raced in several historic races in the US. It was sold again in 2001 to Matthew Drendel where it continued to compete in historic events around the country. After Drendel's death in 2010, the car would later be auctioned at the 2012 Gooding Auction in Iceland for 4.4 million dollars to Jerry Seinfeld.
917/30-005 Parts Car. Build started in 1973 as a 1974 Penske team chassis, but was also suspended because of rule changes. Porsche AG sold the car to Gerry Sutterfield in 1979 who built the chassis into a complete car. Then in the late 1980s the car was sold to Hans Thulin and was stored in his personal car museum, near Malmo in southern Sweden. In 1991 the car was sold to the Meitec Corporation in Japan before being sold again anonymously in 2005. Then in September 2011 John Collins of Talacrest purchases the car before selling again shortly thereafter to Peter Harburg. The car was recently offered at RM Auctions in 2014 but failed to sell.
917/30-006 Parts Car. Build started in 1973 as a 1974 Penske team chassis, but was again suspended because of rule changes. Was sold as a kit set to Vasek Polak in 1982. Later in 1995, Polak would make a copy of the body panels needed to compete the car. The car was completed and sold in 1998 to Chris & Lorraine Gruys, where it was painted in the yellow and red Bosch livery. It was raced in historic events in the US until its sale in 2007 to Jim Torres. Car would be sold again in 2008 to Cavallo Motorsports of California and raced in historic events for a year. Then it was sold in 2009 to Freising Motorsports of Germany where it currently resides in different livery.
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