Porsche 959 Design
The Porsche 959 engine was masterful even for Porsche: a short-stroke version of the 3.3-liter 911 Turbo unit with twin overhead cams per bank, four valves per cylinder, water-cooled heads (air cooling continued for the block), low-mass titanium con rods, and twin KKK turbochargers. Crossover pipes and bypass valves afforded "sequential" turbocharging. Only the port blower was active below 4,000 rpm; the starboard unit progressively phased in as exhaust-gas flow increased toward 4,000, thus marrying low-speed tractability with top-end power. Despite modest 8.3:1 compression, DIN horsepower European was a heady 450.
Putting all that power to the ground was a unique full-time four-wheel-drive system with a six-speed gearbox, basically the contemporary five-speed Carrera unit with an extra-low first, ostensibly for off-road use (and thus marked "G" for Gelande -- terrain). Power was taken aft in the usual way.
With a 450-horsepower "boxer" six, the Porsche 959 had incredible handling.
Drive forward was by a tube-encased shaft to a differential using a multi-plate clutch in an oil-filled chamber. Varying clutch-oil pressure determined the amount of front torque delivered, so no center differential was needed, though a locking rear diff was provided.
Torque apportioning was selectable via a steering-column stalk controlling four computer programs and a full-automatic mode. "Traction" locked the front clutch and rear diff for maximum pull in mud and snow. "Ice" split torque 50/50 front/rear, while "Wet" provided a 40/60 division that progressively increased to the rear on acceleration. "Dry" also offered a static 40/60, but could vary that up to 20/80 in all-out acceleration.
All this was accomplished via the Bosch Motronic engine computer used in conjunction with the wheel-mounted speed sensors of the new antilock braking system (developed with WABCO-Westinghouse) -- a first for a rear-engine Porsche. This apart, the brakes were stock 911 Turbo, albeit with larger front discs.
The suspension departed sharply from the 911 by employing double wishbones all around, plus twin shocks and concentric coil springs at each wheel. The shocks in each pair had separate damping roles; both were computer-controlled according to vehicle speed, with a choice of "soft," "firm," and "automatic" settings.
A computer chip also managed a novel, hydraulic ride-height system offering three levels of ground clearance -- 4.7, 5.9, and 7.1 inches -- plus automatic lowering as needed from about 95 mph for improved fuel efficiency and aerodynamic stability.
The Porsche 959 was built in two forms: a "Comfort" model with air-conditioning, electric seats and windows, 911-type rear seats and the ride-height feature; and as a "Sport" version that deleted those items to weigh 110-130 pounds less. Though the Sport was the one given out to most journalists -- doubtless because it was just a little bit faster (carrying 6.1 lbs/horsepower versus 7.1) -- the differences in performance proved slight.
The Porsche 959 "Comfort" model included A/C and power seats and windows.
Check out the complete story of Porsche cars, including these fabulous models:
|Porsche 356 ||Porsche 911 ||Porsche 914 |
|Porsche 924, 944, 968 ||Porsche 928||Porsche 959|
|Porsche Boxster||Porsche Cayenne||Porsche Cayman|
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