Porsche 917

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-convert|62|mph|km/h|abbr=on time of 2.5 seconds and a top speed of over 254 mph (407 km/h).

In the 1973 Can-Am series, the turbocharged version Porsche 917/30 developed over convert|1100|bhp|abbr=on, and as much as convert|1580|bhp|abbr=on in qualifying tune.

The 917 is one of the most iconic sports racing cars of all time, largely for its high speeds and high horsepower outputs, and was made into a movie star by Steve McQueen in his 1971 film "Le Mans".

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 7 litre Ford prototypes, as well as to entice manufacturers who were already building 3 litre Formula One engines into endurance racing, the Commission Sportive Internationale (then the independent competition arm of the FIA) announced the World Championship of Makes would be run for 3 litre open prototypes for four years from 1968 through 1971.

Well aware that few manufacturers were ready to take up the challenge immediately, the CSI allowed the participation of 5 litre sports car manufactured in quantities of 50 in the Sport category, which was called Group 4, [ [http://www.fia.com/resources/documents/2102817986__Hist_App_J_69_Art_252_a.pdf Appendix J 1969, Art. 251, Art. 252] on [http://www.fia.com/ www.fia.com] ] targeting existing cars like the aging Ford GT40 and the newer Lola T70 coupe.

In April 1968, the CSI announced that the minimal production figure to compete in the Sport category of the World 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, mainly to allow the homologation of the Ferrari 250 LM and the Lola T70Fact|date=January 2008 (which was not manufactured in sufficient quantities, unless the open Can-Am T70s were counted as well) as there were still too few entries in the 3 litres Prototype category.

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, they decided to conceive, design and build 25 versions of a whole new car 4.5 litre for the Sport category with one underlying goal: to win its first overall victory in the 24 Hours of Le Mans. 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 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 one of the cars, which was declined. [ [http://www.porsche917.com.ar/xhistoria1969_1.htm Porsche 917 History - 1969 Season (Part 1)] on [http://www.porsche917.com.ar www.porsche917.com.ar] ]

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.

Construction

The car was built around a very light spaceframe chassis (convert|42|kg|lb|abbr=on) and powered by an air-cooled 4.5 litre Flat-12 with a 4 ratio transaxle. To keep the car compact despite the large engine the drivers seat was so advanced to the front of the chassis that the feet of the drivers were in front of 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.

Racing history

1969

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 was 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 convert|30|km/h|mi/h|abbr=on 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. 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 convert|120|m|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.

1970

Disappointed by the poor results of the 917 in 1969, and facing new competition, Porsche concluded an agreement with John Wyer and the Gulf Team, which became the official Porsche team, and also the official development partner. During tests at Zeltweg, where the car had won its only race at that time, Wyer's engineer John Horsmann had the idea to increase downforce at the expense of drag. A new wedge-shaped tail was molded with aluminium sheets taped together. This new short tail gave the 917 much needed stability. The plastic engine intake cover had already been removed. The new version was called 917K (Kurzheck).

Wyer was surprised to discover that another team was carefully preparing for 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 had made major efforts to win the race with competing teams.

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 including partially covered rear wheel arches which had very low drag, yet better stability than the 1969 version. A few 4.9 litre engines were available for some cars, but these proved to put too much strain on the gearboxes.

Two 917 LH were entered in Le Mans, one by Porsche-Salzburg, the other by Martini Racing. The spectacular livery of this car was an elaborate whirls and swoops of light green on a dark blue background. The car gained the nickname of the "Hippie Car" or the "Psychedelic Porsche" from the team and media. The Porsche-Salzburg's LH was powered by a new 4.9 litre engine that Porsche had introduced at Monza.

Wyer lined up three 917Ks, two with the 4.9 litre engine and one with the 4.5 litre unit. Porsche-Salzburg also entered a 917 K with the standard 4.5 litre engine for Hans Herrmann and Richard Attwood.

Early in the race, most of the Ferrari entrants eliminated each other in a shunt. The two Porsche factory teams, Gulf-Wyer and Porsche Salzburg, continued to battle each other. 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 917LH with a green "psychedelic Hippie" design came in 2nd.

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, at least on some tracks.

During the 1970 season the FIA decided to eliminate the loop-hole "Sport" category at the end of the 1971 season, when the rules expired, so the big 917s and 512s would have to retire at the end of the year. 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. The Gr.5 category, would temporally disappear until 1975, when it was reamended for production cars.

Being cheaper than the 917K, the 512M appeared a bargain for customers at the end of 1970 - a consolation that had hardly been imaginable only two years previously. Porsche, an underdog for 20 years, had turned itself into the new superpower of sports car racing with the 917. In addition, the lightweight and compact Porsche 908/3 were available for the slow and twisty tracks of Nürburgring and Targa Florio.

1971

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 second 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 and the Targa Florio, 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".

Yet 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 still stands.

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. A 16-cylinder with about convert|750|hp|abbr=on was tested, but a turbocharged 12-cylinder had initially the same power, with more to come. 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 850hp 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 convert|1580|hp won the 1973 edition winning all races but one with Mark Donohue driving. 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 the Indy 500 and F1.

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 US 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 convert|1560|bhp|abbr=on with twin turbochargers run up to full boost, a simply astonishing 39 psi, though it usually raced with around convert|1100|bhp|abbr=on at 7,800 rpm to preserve the engine. The 917/30 dominated the Can-Am series during the 1973 season. The 917/30 could go from 0-convert|60|mph|km/h|abbr=on in 1.9 seconds, 0-convert|100|mph|km/h|abbr=on in 3.9 seconds, 0-convert|200|mph|km/h|abbr=on in 10.9 seconds, and on to a top speed of 257 mph +, (413 km/h +) .These staggering levels of performance, the 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.

In 1975 Mark Donohue ran a 917-30 around the convert|2.66|mi|km|sing=on tri-oval Talladega Superspeedway, in Talladega, Alabama setting a closed course land speed record of convert|221.160|mi/h|km/h|abbr=on. The record stood for four years.

1981

In 1981, it appeared that new Le Mans regulations would allow a 917 to race again.The Kremer Racing 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 sendoff 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. [ [http://8w.forix.com/6thgear/fastestraces-laps.html Fastest races and laps ever] on [http://8w.forix.com/ 8w.forix.com] ] 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 1986.

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.

Astonishingly, despite the car's impracticality, at least two 917s were road-registered. One, for Count Rossi of the Martini concern, was painted silver and given the Alabama plate 61-27737 to circumvent red tape in Europe, and the second, for Joachim Grossmann, was painted white and given the German registration CW-K 917.

Recently, high end replicas that use the flat-6 from the 911 have become available. One is built in Australia by Kraftwerkz, [ [http://www.project917.com/ Original "Project 917" Web Page] ] [ [http://www.kraftwerkz.net/ Kraftwerkz presents The LMK917 Porsche 917 Replica] ] another in the US by Race-Car Replicas. [ [http://race-car-replicas.com/rcr917.html Race-Car Replicas 917] ]

In addition, a very nice grass roots "replica," the Laser 917, [http://www.laser917.net/infusions/registry/registry_view_photo.php?A=405&B=121] . which is essentially a rebodied VW Beetle, was featured in "Herbie Goes to Monte Carlo". Driven in the film by Bruno von Stickle (Eric Braeden), and painted in the colors of Germany's national flag, being powered by a Corvair flat-6 it was perhaps the most formidable entry in the fictitious Trans-France Race.

Video Games Appearance

* (Sony Playstation 1, 24 March 2000, United States release)
*Le Mans 24 (arcade game) (Sega video arcade game, 1997)

Notes

References

* [http://www.fia.com/sport/Regulations/histracing.html FIA Historic Racing Regulations]
* [http://www.fia.com/sport/Regulations/histappjregs.html Historic Appendix J Regulations]

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)

External links

* [http://www.research-racing.de/917-a.htm Gulf Porsche 917] on [http://www.research-racing.de/ www.research-racing.de]
* [http://www.atspeedimages.com/pebble_2004/monterey_historics/1969_porsche_917k/ 1969 Porsche 917K] (with bodywork updated to 1970 spec) on [http://www.atspeedimages.com/ www.atspeedimages.com]
* [http://www.porsche917.com.ar/ Porsche 917 History, models, pilots, ...] on [http://www.porsche917.com.ar/ http://www.porsche917.com.ar/] . Spanish and English versions.

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