Valve timing is controlled via a vane cell adjuster which continuously varies the two intake · camshafts positions relative to cra

Valve timing is controlled via a vane cell adjuster which continuously varies the two intake camshafts positions relative to crankshaft. The adjustment range covers a 40° range of crankshaft angle. Valve lift is varied by a system utilizing two cup tappets, one resting in the other. These tappets are actuated by separate cam lobes of differing size. The engine control module directs oil pressure to the appropriate tappet based on engine speed and load parameters. When non- pressurized, the tappet moves under the camshaft lobe, but exerts no pressure on the valve, in effect free wheeling. Transmitting the torque to the tires Like the 911 Turbo Coupe, the new Turbo Cabriolet is available with a choice of transmissions: six- speed manual gearbox is standard equipment. A five-speed Tiptronic S is optional. Both boast closely-spaced gear ratios for rewarding performance as well as overdrive top gears for relaxed and economical cruising. Despite the 911 Turbo Cabriolet's awesome torque, the engine's output is handily channeled through the six-speed manual. Clutch actuation is hydraulic. Gear changes are crisp and direct thanks to the compact design of the powertrain unit and the solid linkage. The optional five-speed Tiptronic S allows the driver to permit the transmission to shift gears automatically or shift for himself via steering-wheel mounted paddles. In startling contrast to other makers' automatic transmissions, the Tiptronic S in the Turbo Cabriolet delivers quicker acceleration than is possible with the manual gearbox. In track testing with factory drivers, the open-top 911 Turbo with Tiptronic S accelerated to 60 mph (96 kph) 0.3 seconds faster than the Turbo Cabriolet with six-speed manual gearbox. And unlike other makers' automatic transmissions, the Turbo Cabriolet's Tiptronic S starts from a stop in first, not second, gear for a quick launch. The comforting stability of all-wheel drive To ensure that the engine's output is put safely and competently to the road, all 911 Turbo Cabriolets are equipped with the Porsche all-wheel drive system, Porsche Traction Management. Unlike other manufacture’s all-wheel drive systems with viscous couplings, Porsche Traction Management relies on the instant response of an electronically controlled, electro-magnetic multiplate clutch pack to distribute engine torque to the front and rear wheels as conditions demand. Since it is electronically controlled, Porsche engineers integrated PTM with Porsche Stability Management (PSM). The systems complement each other to deliver the most available traction for supreme driver confidence regardless of the situation or road surface. The Porsche purist’s bias For spirited driving fun and crisp response, Porsche vehicles have been rear-wheel drive since the marque’s inception. This is still the case with PTM. In most driving situations, power is directed to the rear wheels. Within 100 milliseconds of detecting impending wheel slippage, PTM can redistribute engine torque to the non-slipping wheels. By constantly monitoring input from throttle- and steering wheel-position sensors as well as wheel- speed sensors, PTM anticipates slippage before it can occur.