The Porsche 959 was one of the 80’s ultimate supercars and may also be considered as the first car of the supercar species. 959 also stands for the superb technology platform in which the latest technical innovations from the famous Porsche development centre Weissach were included. It’s only rival at the time was another legend: the radical lightweight bi-turbocharged Ferrari F40.
The 959 was powered by a new and revolutionary 2.85 litre flat-six engine derived from the famous “Moby Dick” race car. It featured numerous technical innovations of which the most prominent are 4-valve water-cooled cylinder heads, aluminium forged pistons, titanium con-rods, DOHC, two sequential turbochargers, dry sump lubrication and a BOSCH Motronic featuring digital injection and ignition. The cooling system of the 959 is a water-air-cooled hybrid where the cylinder heads are water cooled and the engine block is air-cooled.
The use of sequential twin turbochargers (two small KKK turbochargers) rather than the more usual identical turbochargers for each of the two cylinder banks allowed a smoother and seamless delivery of power across the engine RPM band, in contrast to the abrupt “on-off” power characteristic that distinguished the 959 engine from Porsche’s other turbocharged engines (930 and also 964 turbo) of the era. Sequential turbo charging was controlled as follows: below 4,000 rpm, as exhaust gas was not enough for driving both turbines efficiently; all the exhaust gas was fed to a single (small) turbo. This made the turbo operating earlier and therewith allowed the engine to build up boost earlier compared to using a conventional turbocharger setup. Between 4,000 and 4,200 rpm, the second turbo started “pre-spinning” (preparing for engaging soon at higher revs). Above 4,200 rpm, the two turbos operated simultaneously to provide full boost up to 0.9 bar (12.8 psi) in the high revs.
The 959 powerplant produced an impressive 450bhp @ 6500rpm and 500Nm @ 5500rpm. Thanks to the sequential turbo charging setup, 400Nm were already available at 2500rpm only.
Borg Warner contributed a six-speed manual gearbox to the 959 project allowing the car to be driven in optimum torque range at virtually every speed.
Porsches PSK (Porsche-Steuer Kupplung) system developed for and introduced with the 959 was like no other system. Even today it is still regarded as one of the most sophisticated 4WD system ever made because among all the various four-wheel drive designs available, PSK is the only one which can vary the front / rear torque split ratio under normal running condition, while other designs can only reallocate when tire slip occurs. PSK in contrary determines the most suitable torque split ratio by analysing various parameters such as throttle position, steering angle, g force and even turbo boost. The PSK system provided near perfect traction and therefore was not comparable to any other four-wheel drive systems. The PSK used the following split ratios for “standard situations”:
In most of the time, torque split between front and rear was 40 : 60, that is, the same as the car’s weight distribution which made the best overall traction. Under hard acceleration, PSK transferred up to 80% torque to the rear wheels as the dynamic load distribution also moved to the rear axle. On slippery surface, 50 : 50 torque split was used.
PSK and the new generation of engine weren’t the only superb innovations introduced with the 959. The suspension setup included double wishbones on the front and rear including twin damper setup. This suspension featured adjustable ride height as well as adjustable damping.
The adjustable ride height function was designed to achieve high speed stability without compromising low speed ride comfort. The 959 “Komfort” version allowed the driver to select a ride height (ground clearance) of 12 cm, 15 cm or 18 cm. The adjustable damping also had 3 settings. To implement the adjustable ride height and damping, each wheel was equipped with 2 dampers. One of them had an electric motor to vary the damper’s valve system in order to control adjustable damping. Another damper, whose fluid pressure was controlled by a hydraulic pump driven by the engine, adjusted the ride height.
Porsche fitted ventilated 322 mm (front) and (rear) 308 mm discs (in Sport version, also cross-drilled) to the 959. They were compressed by four-piston aluminium callipers and braking process was controlled by a four-channel BOSCH ABS with sensors on all four wheels, this also being an innovation as it was the first time that ABS was implemented in a supercar.
Porsche rounded off this selection of high-tech innovations by fitting 17inch Magnesium hollow spoke design wheels to the 959. These wheels were fitted with surprisingly narrow 235/45 and 255/40 tyres (F40 and Lamborghini Countach had much wider tyres fitted but were rear-wheels cars only) and included pressure control.
The 959 chassis was derived from the 911, so all important dimensions and hard points were basically given – the wheelbase was exactly the same as with the 911, the 959 was 65mm wider than the 911 Turbo. Porsche designed the aerodynamics of the 959 to meet with their “zero-lift” dynamics concept in order to keep the car driveable also at speeds above 300km/h. Therefore the 959 looks quite different from the 911.
Porsche used aerospace technology to manufacture the bodywork of the 959. The roof, fenders and the rear section were made of Kevlar, the front bumper from polyurethane and front bonnet and doors were made of Aluminium.
According the performance tests by Auto Motor und Sport (issue 12/87), the Porsche 959 accelerates from a standstill to 100km/h in 3.7s and to 200km/ in 13 seconds. The top speed of 317km/h was clocked on VW test circuit Ehra Lessien. Both performance numbers marked a new world record for production cars.
The 959 also was a successful racecar, both in rally (Gruppe B) and track racing (Endurance).
Rallye Raid Version – 959 Group B
The 959 was designed to comply with the FIA Group B regulations and therewith theoretically allowed to compete against Audi Quattro Sport, Lancia Delta S4 and Peugeot 205 T16 in the World Rally Championship, which was the most exciting and most sophisticated rally category ever appeared. Due to financial reasons and the fact that the 959 was too heavy compared to its competitors (eg. Lancia Delta S4: 470bhp @ 890kg), Porsche chose to participate in the very famous Paris Dakar rallye where the 959 competed against “easy prey” like Mitsubishi Pajero, Opel Manta and Mercedes G-Wagen. Porsche used this event for PR purposes and to test the 959 in the worst conditions.
In 1984, Porsche participated with three Porsche 911 4X4 featuring the 959 four-wheel drive system (excluding the torque split function). They finished 1st, 2nd and 26th.
1985 Porsche entered Paris-Dakar with three 959 prototypes featuring the complete 959 four-wheel drive and suspension but a normally aspirated engine donated by the 911 Carrera 3.2. All cars retired with mechanical problems.
In 1986 the 959 Rallye car was completed including the new engine and was almost identical to the production model “Sport” version with increased ground clearance. The engine was restricted to 400bhp in order to function properly with the inferior African fuel quality. Porsche won also this rallye placing 1st, 2nd and 5th.
Circuit version – Porsche 961
The 961 was the 959 based Le Mans racer competing in the FIA GTX class: The body was thoroughly lightened reducing kerb weight to 1,150 kg. A bigger rear wing and revised air dam were fitted to adapt the 959 body for track racing.
The engine was modified returning the turbochargers into parellel configuration as for the Group C engine. Boost was raised to 1.4bar resulting in an output of 680 hp (959: 0.9 bar). Brakes were donated by the 962. The 4-wheel drive – quite rare – was retained but was set to heavily rear-biased 20 / 80 split ratio.
On its first outing in 1986 Le Mans 24 hours, the 959 finished 7th overall, or 1st place in IMSA GTX category. All the cars in front of it were Gruppe C cars which meant a very impressive result. However, in those days, Gruppe C was the majority and the highlight in endurance racing. The IMSA GTX did not attract much attention from car makers as well as spectators, so 961 did not really proved its superiority.
In 1987 the 961 started in Le Mans but retired following an accident.
Even if the 959 / 961 motorsport history is short it still is very impressive as this car is very close to the “standard” model and was both successful in rally and track racing.
Source – http://www.deutschnine.com/