Smooth, light intake · To be sure that the Turbo Coupe's engine gets a constant and adequate supply of intake charge

Smooth, light intake To be sure that the Turbo Coupe's engine gets a constant and adequate supply of intake charge air, Porsche engineers optimized intake flow. The intake manifold halves are formed of a single piece of synthetic material. This manifold is about 4.4 pounds (2 kg) lighter than the one in the previous model while offering improved airflow. The air filter housing was also redesigned and the filter element now has a recommended service life of 40,000 miles. Sodium-filled exhaust valves with modified springs A variable-turbine geometry turbocharger means increased exhaust gas backpressure. To take this into account, the Turbo Coupe's exhaust valve springs are of a modified construction. Their design ensures the valves continue to close properly and securely. With the valves closed, the springs create a higher closing force without changing the force exerted by the springs under maximum valve lift. This helps prevent increases in friction losses. As on the previous Turbo, the exhaust valves have sodium-filled stems. The sodium liquefies at combustion temperatures, and draws heat from the valve face, helping keeping the valves cool even during periods of hard use. Transmitting the torque to the tires The 911 Turbo Coupe is available with a choice of transmissions: six-speed manual gearbox is standard equipment. A five-speed driver-shiftable Tiptronic S is optional. Both boast closely spaced gear ratios for rewarding performance as well as overdrive top gears for relaxed and economical cruising. Revised six-speed manual In consideration of the engine's bodacious output, the entire gearbox has been reinforced and its cooling system improved. Reinforcements have been made around the drive head (crown and plate wheel) and on the individual gear sets. Modification of the fins on the gear casing and an additional vent opening in the underfloor cover improve the gearbox's cooling. Structural reinforcements on the housing reduce the transmission of airborne sound waves. Gearshift travel is about 15 percent shorter due to a change in the location of the pivot point. First and second gear boast triple carbon mechanisms. Third through sixth have dual carbon synchromesh mechanisms. The use of carbon coatings enables the gears to handle higher loads, and improves gearshift feel while maintaining the same service life. Clutch actuation is hydraulic. Gear changes are crisp and direct thanks to the compact design of the powertrain unit and the solid linkage. Enhanced Tiptronic S The planetary gearsets in the Turbo Coupe's Tiptronic S have been strengthened, commensurate with the engine's stupendous torque. In addition, the shifting and reaction times of the unit are quicker than before.