Porsche 956

Porsche
956
Production period:	1982-1984
Class :	race car
Body versions :	Coupe
Engines:	Petrol engines : 2.65 liters (455–470 kW)
Length:	4800 mm
Width:	1990 mm
Height:	1080 mm
Wheelbase :	2650 mm
Empty weight :	820 kg
Previous model	Porsche 917 , Porsche 936
successor	Porsche 962

The Porsche 956 was a sports car prototype from 1982 to 1984 all titles of the FIA - World Sportscar Championship won, both in the ratings for the driver and the brands.

development

In the course of motor racing, the regulations were changed several times. There was a significant break from 1982, when the previous groups 1 to 6 for sports and touring cars were reduced by the FIA to just three categories, groups A (large-scale touring cars), B (small-series GTs) and C (sports cars Prototypes). In the sports prototypes, the previous two-seater open Group 6 sports cars, in which the engine was limited to 3 liters (or 2.14 liters with supercharging, factor 1.4), were replaced by Group C. Closed coupés were mandatory here, similar to the Porsche 917 , Ferrari 512S or Lola T70 until 1971 . As an innovation, the available fuel was limited, while the engine design was subject to few restrictions so that the most efficient concept could prevail. For this new group the Porsche 956C was developed, as well as the Ford C100 , Lancia LC2 and others.

Until 1978, Porsche competed at the Le Mans factory with the Porsche 936 and otherwise sold numerous Porsche 935s to customers according to Group 5 rules. The FIA ​​decision made these vehicles ready for museums. Only in the USA did other rules apply, something Porsche had to experience several times before. Based on the air-cooled 6-cylinder boxer engine of the Porsche 935, which in the 1978 works car with twin-turbo or twin-turbo charging, water-cooled four-valve heads and 3.2 liters displacement, developed well over 700 hp. In 1979, the Porsche Interscope project was based on the American Rules developed a 2.65-liter engine for methanol fuel, but was "slowed down" by changing the rule for the boost pressure before the Indianapolis 500 mile race in 1980. For group C an engine was to be derived from this, which was again designed for gasoline. The 2649 cm³ were initially retained. The engine developed 455 kW (620 hp) at a speed of 8000 rpm and was successfully tested in two Porsche 936 chassis at the Le Mans 24-hour race in 1981 , where special rules applied. It won Jacky Ickx and Derek Bell , the second car was twelfth.

The chassis for the 956 had to be completely redeveloped by the Porsche engineers under the direction of Norbert Singer , because the tubular frames previously used were no longer up to date. The lighter and more stable aluminum monocoque introduced by Lotus in the 1960s had long since become the standard and has just been replaced in Formula 1 by the even better carbon fiber reinforced plastic (CFRP), and also for the McLaren team , for which Porsche created the TAG V6 turbo engine developed. Porsche did not use this opportunity to transfer technology in the following years either and for the first time constructed an aluminum chassis in a shell construction, which proved to be a weak point of the 956.

The aerodynamic properties also became increasingly important compared to older racing cars from the 1960s and 1970s, for example the ground effect introduced by Lotus or the wing car , in which the curved underbody generates a lot of downforce. The wide boxer engines in Formula 1 had proven to be unsuitable for this, which is why the TAG engine was developed in V6 form, but Porsche continued to use the flat design typical of the company for sports cars. The outer skin, the underbody, the diffuser in the rear and the wing were optimized in such a way that the resulting negative pressure literally sucked the car onto the road surface ( ground effect ). As a result, previously unimagined cornering speeds could be achieved. The top speed of the 956 on the 5-kilometer straight in Le Mans was around 350 km / h, over 30 km / h less than in 1971 for the similarly powerful five-liter Porsche 917 with long tail.

Another problem was the windshield, which, like the earlier 917, was supposed to be curved in two directions. The manufacturer had problems with this, so they installed a pane that was only curved in the shape of a cylinder, the upper edge of which was usually 100 cm high (see Ford C100 ). Their straight profile was also easier to keep clean with the windscreen wiper, an advantage in rain races and at night. The bikes were developed together with Speedline .

Racing history

1982 works car

The first copy of the 956 was tested by Jürgen Barth on the in-house track in Weissach from the end of March . The 1000 km race in Monza in mid-April was still left out; the 956-001 made its debut at the 6-hour race in Silverstone in mid-May 1982 , where it set the fastest time in practice thanks to modern aerodynamics and the turbo engine concept. Since there were hardly any group C cars available, transitional rules applied so that cars according to group 5 and 6 as well as the American IMSA GTX class could continue to participate. In the race, Ickx / Bell took second place behind an open Lancia LC1 , which was not subject to the fuel limit, but was also not entitled to brand championship points. The Nürburgring , whose track characteristics promise little knowledge for Le Mans, was left out in favor of further development and the construction of three new chassis for the season highlight.

In the 1982 Le Mans 24-hour race, two of the 956 started from the front of the 55-car field. Although 28 Group C cars had appeared, new designs or Porsche conversions such as the 936C from Joest or the CK5 from Kremer , only the Ford C100 was from a large-scale manufacturer. Only 18 cars were rated in the end, including three from Group C: an Aston Martin Nimrod in 7th place and two Rondeau . The three 956s used by the factory achieved a triple victory over older Porsches by a large margin. As in the previous year, Jacky Ickx and Derek Bell won . As last year's winner, they had start number 1 on the car, the other two works cars followed in the order of their start numbers 2 and 3.

At the next World Championship round, the 1000 km from Spa , the factory 956s from Ickx / Mass and Bell / Schuppan were able to just beat the Lancia. The 1000 km from Mugello wasn't just missing the Porsche factory. Lancia scored a double victory against just 17 opponents. In the 1000 km from Fuji Ickx / Mass prevailed over a Lancia, the numerous locals were u. a. at the start in Honda Civic and VW Golf GTI. At the end of the season 1000 km from Brands Hatch , the factory only sent a 956. Ickx again narrowly beat a Lancia and became world sports car champion. Third place went to a Porsche 935 from Group 5, the rest of the top 10 were group C vehicles, led by two Ford C100s.

1983 customer car

The first twelve 956s were delivered to customer teams in 1983, which differed from the factory cars from 956-001 onwards by their consecutive chassis numbers from 956-101. The Ford C100 did not return, the Lancia LC now also complied with Group C rules and turned out to be the only opponents worth mentioning, finishing second at the end of the season in Kyalami just before Christmas. Otherwise, at least the first four places went to the Porsche 956, which made the world championship races among themselves.

In 1983 Bellof also lapped the legendary Nordschleife with the works 956 during training for the 1000 km race on the Nürburgring as the first person with an average speed of over 200 km / h and was only beaten by a Porsche 919 Evo in 2018. In the race, however, his 956 took off on the “big jump hill” in Pflanzgarten and overturned. In Le Mans, Porsche would have occupied the first ten places if a Sauber C7 with a BMW engine had not secured ninth place, which Porsche commented with “Nobody is perfect”. To the chagrin of the customer teams, the plant continued to operate successfully: two works cars won again at Le Mans, and Ickx was again the sports car driver's world champion. The brand classification had been firmly in Porsche hands since 1978, and at least one class title has gone to Porsche since 1962.

1984 Introduction of the 956B and 962

Porsche 956B-114 from 1984, at ( Goodwood Festival of Speed 2007)

For the 1984 World Endurance Championship it was announced that the amount of fuel would be reduced from 600 liters of fuel for 1000 kilometers to 510 liters. Porsche replaced the mechanical injection system with an electronic one from Bosch. This evolutionary stage was designated as 956B; the chassis numbers delivered to customers in 1984 began with 956B-113. The engine with the more modern injection system was more economical and was still able to increase engine performance. An output of 470 kW (640 hp) was now available at 8200 rpm. The Porsche 956, whose main opponent was the Lancia LC2 , usually achieved at least one-two victories, with Kyalami again being an exception. Only one 956 started in South Africa and finished ninth even behind compact cars. After a dispute with the ACO, the plant did not take part in Le Mans. The best of the seven 956 in the first place was the 956B-117 of the Joest Racing customer team . Factory driver Stefan Bellof from Gießen became the long-distance world champion, making him the first German world champion on the circuit.

In the important US market, the IMSA series of Porsche 935s according to GTX rules were successful for a long time, but from 1981 competition arose from the Chevrolet engine-powered GTP prototypes from Lola and March, which were able to generate significantly more downforce. According to the requirements of the GTP class, which u. a. prescribed a tubular steel roll cage and pedals behind the front axle for safety reasons, a variant of the 956 with a 12 cm longer wheelbase was designed and named the Porsche 962 . The 962, which initially had to be equipped with the older, but more cost-effective Porsche 935 engine, made its debut in Daytona at the beginning of 1984 with the fastest time in training. From the middle of the season onwards, the delivered customers won 962 IMSA races. But some also took part in World Cup races.

1985 962C

In 1985 Jonathan Palmer , James Weaver and Richard Lloyd drove this Porsche 956 in second place in the Le Mans 24 Hours

The 1987 LM winner, a Porsche 962C, in the Porsche Museum in Zuffenhausen

After a visit by the then FIA President Jean-Marie Balestre to the 24 Hours of Daytona in 1984, the decision was made to adopt some of the rules in the IMSA GTP. Although the originally intended discontinuation of the consumption rule was waived, among other things after the boycott of the Porsche works team in Le Mans in 1984, steel roll cages and the arrangement of the pedals behind the front axle line were prescribed from the 1985 season, analogous to the IMSA. Vehicles manufactured after January 1, 1985 had to comply with the rules; existing racing vehicles were subject to a transition period until December 31, 1986. This ended production of the Porsche 956, and from the 1985 season onwards, the plant started using the new Porsche 962C and supplied these vehicles also to its customers. A total of 10 factory chassis were built and 17 customer cars were delivered - the successor was to be built around 90 times. The Porsche 956 dominated the Group C races from mid-1982 to 1985, when Joest's 956 won Le Mans again.

The racing car was driven by well-known racing drivers such as Stefan Bellof , Jacky Ickx , Jochen Mass , Derek Bell , Hans-Joachim Stuck , Manfred Winkelhock and Vern Schuppan . Bellof died in Spa-Francorchamps in 1985 after an unsuccessful overtaking maneuver at the entrance to the Eau Rouge in a privately used Brun-Porsche 956B-116, while opponent Jacky Ickx in the newer factory 962C was unharmed. Manfred Winkelhock died three weeks earlier in Mosport, Canada, after his 962 collided with a wall.

The results from 1982 to 1986

In the tables, a maximum of the first 20 places for each race are listed in which a Porsche 956 placed.

1982

1983

1984

1985

1986

Technical specifications

The Porsche 956 was produced and used from 1982 to 1984 in the following versions:

Porsche 956:	956 (up to model year 1983)	956 (from model year 1983)
engine	6-cylinder boxer engine (four-stroke), two turbochargers with charge air cooling next to the cylinder heads
Displacement	2649 cc
Bore × stroke	92.3 x 66 mm
Power at 1 / min	455 kW (620 hp) at 8200	470 kW (640 hp) at 8200
Liter output	172 kW (234 PS) / liter	178 kW (241 PS) / liter
Max. Torque at 1 / min	630 at 5400
compression	7.2: 1	8.5: 1
Valve control	four overhead camshafts (two per cylinder bank) with steering wheel drive
cooling	Air cooling (fan), cylinder heads with water cooling
transmission	5-speed gearbox, rear-wheel drive , three-plate clutch	5-speed gearbox, rear-wheel drive, single-disc clutch
Brakes	Disc brakes with internally ventilated discs, diameter 33 cm, thickness approx. 3 cm, two brake calipers per wheel, hydraulically operated, two hydraulic circuits
Front and rear suspension	Independent suspension on double wishbones, wheel hub carriers made of magnesium
Front suspension	External coil springs and Bilstein shock absorbers
Rear suspension	Coil springs and Bilstein shock absorbers, V-shaped inside
body	Aluminum monocoque with plastic body (reinforcement ribs made of CFRP)
Track width front / rear	1648/1548 mm
wheelbase	2650 mm
Tires rim
Dimensions L × W × H	4770 × 2000 × 1030 mm
Empty weight	820 kg-850 kg
Tank capacity	99.5 liters (tank behind the driver)
Top speed	over 350 km / h
Acceleration 0-100 km / h	3.4 s

In addition, different body versions were used: On the Le Mans track, which is geared towards maximum speed, all racing teams used the so-called long tail , on the other racetracks, however, the short tail (the only exception: at the 1000 km race in Silverstone , Porsche Kremer Racing and Preston Henns T- Bird Swap Shop each with a long tail part). Later - from 1984 to 1986 - racing versions with front wings were also used, especially at the Richard Lloyd Racing team. The 956 was increasingly replaced by the 962C, and in 1987 only successor models ran in all races of the World Sports Prototype Championship .

literature

• Gustav Büsing, Michael Cotton, Ulrich Upietz: Porsche 956 - 962. Gruppe-C-Motorsport-Verlag, Duisburg 2003, ISBN 3-928540-40-8
• Peter Schneider: Type compass Porsche. Racing and racing sports cars since 1948. Motorbuch Verlag, Stuttgart 2003, ISBN 3-613-02300-8

Web links

Commons : Porsche 956  - Collection of Pictures, Videos and Audio Files

• Chassis numbers of the 956 (and 962 )
• Chassis numbers from 956 and 962 ( Memento from October 17, 2007 in the Internet Archive )

Individual evidence

1. ↑ Peter Morgan: Porsche 956/962 - The enduring champions . Haynes Publishing, Sparkford, Yeovil, Somerset, UK 2003, ISBN 1-85960-951-1 , pp. 208 .