PORSCHE 959
By Carlo Brema / Photos Porsche
In the second half of the 80s the Porsche 959 defined the most effective and versatile image of a sports car with on demand performance, all thanks to a project that implemented technologies once unknown to the road cars production. Wizardries such as tire pressure sensors, the sophisticated electro-hydraulic control of the chassis implemented by two shocks per wheel and the all-wheel-drive “4” called PSK (Porsche-Steuer-Kupplung), represented the technological heart of the car. The PSK was designed as a complex system of four-wheel drive capable of varying torque distribution even in conditions far from grip limit. It worked with a drive shaft culminating in a front differential with multi petal clutches handled electronically: varying the hydraulic pressure was possible to distribute torque and control values as the steering angle, throttle position, turbo pressure, lateral G force and last but not least, the speed of each wheel, detected by the first ABS sensors in the world ever installed on a supercar.
In contrast to a normal limited slip differential that reacts to loss of traction, the PSK boasted three options selectable by the driver: “Dry”, sharing at 40:60 between the front and rear axle (identical to the balance of the car weight) and variable until 20:80 “at full throttle”. This logic is translated into the best grip possible for each wheel, taking into account the natural dynamic transfer of the weight. 3.9 sec for the 0-100 remained the reference figure for the era. Moreover: “Wet”, always at 40:60, however, could increase the rear balance during acceleration and finally ”Traction” and ”Ice” with a 50:50 distribution, but with differential fully closed in the first case.
The name of the first prototype presented in Frankfurt in ’83 reveals that everything was studied to participate in the most incredible and technological (but dangerous) world rally ever existed, which allowed the registration of cars produced at least in 200 units. Needless to say, that cars like the Lancia Delta S4 and Peugeot 205 T16 (just to name two) mimicked the name and appearance of a normal production car only for marketing reasons, while below, concealed real experimental prototypes with performance comparable to F1 of that era. The Group B from Stuttgart made a small exception adopting the already valid chassis (but not as light as a sub-frame or one in composites) of the 911, which remained unchanged in its wheelbase and maintained that friendly-look despite the structural reinforcements and improvements, as well as the brakes, which were those of the Turbo version even if with larger front discs.
The rest was designed and developed from scratch, giving life to 292 units produced (including 29 in the sport version), which, boasted aerospace technology in the construction of the body in Kevlar with a 0.31 cx and neutral lifting values. To push the world’s fastest road car (317 kph, later surpassed by the Ferrari F40 with 321 kph) was taken in the game an innovative and refined six-cylinder boxer engine derived the Porsche 935 “Group 5”. Short-stroke version, 2.85 liters, derived from the 3.3-liter turbo 911-series 930. This softened variant guaranteed 450 hp at 6.500 rpm and 500 Nm at 5.500 rpm; 400 of which are already available at just 2.400 rpm, thanks to the sensible decision to use a small size sequential twin turbo “KKK” solution that reduced the annoying turbo-lag of the original 930/60’s engine.
Other features, some derived from those adopted to reach serious figures in “Group C” were important to develop the 959 also as a laboratory for future models. It’s not a case, if it gained 1st, 2nd and 5th place at the Paris-Dakar in ‘86 or win its IMSA GTX class at the 24h of LeMans always in 1986. Closely derived from the road version of the 959, it was in fact approved a version called 961, that showed that the quality of the project was awesome, even compared to the most extreme “Group C” cars, prototypes specifically designed for the most famous endurance race in the world.