The tires are mounted on forged wheels, developed exclusively for the Turbo. They feature two- · tone, tri-spoke design. Apart fro

The tires are mounted on forged wheels, developed exclusively for the Turbo. They feature two- tone, tri-spoke design. Apart from lower weight, forging technology helps reduce the cross-section of the spokes to a minimum, providing a clear, unobstructed view of the brake calipers. Since tire inflation pressure is critical for safe handling and optimum fuel economy, the Turbo comes standard with the Porsche Tire Pressure Monitoring System (TPMS). Sensors at each wheel constantly monitor pressure of each tire. Should inflation pressure drop by more than 2.9 psi but not as much as 5.8 psi from specifications, the driver sees a text message in the instrument cluster. This warning appears for ten seconds when the car is started. If pressure drops by more than 5.8 psi or if the pressure drops at a rate of 2.9 psi per minute or faster, the warning becomes more serious. The text message is red and comes on as soon as the thresholds are exceeded, whether the vehicle is moving or not. To help keep unnecessary vehicle weight to a minimum, the Turbo Coupe has no spare tire, jack or tire-changing tools, saving approximately 22 pounds (10 kg). Instead, the car is equipped with a small electric air compressor and emergency tire sealant to allow the driver to get to a service station to have the damaged tire properly repaired or replaced. Powertrain Details Astounding output per liter As with every Porsche Turbo sports car before it, the heart of the new 911 Turbo Coupe lies behind the passenger compartment: The unique Porsche turbocharged six-cylinder engine. The 3.6-liter flat six develops 480 bhp (353 kW) at 6000 rpm, or an awesomely efficient 133 bhp (98.1 kW) per liter. Given the Coupe's low 3494-pound mass (for the manual gear box model), the 911 Turbo Coupe has an outstanding power-to-weight ratio of only 7.28 pounds/hp. But knowing full well that torque is what moves the automotive world, Porsche engine designers developed a twin turbocharged engine that offers a peak torque of 460 lb.-ft. (624 Nm) available over an extremely broad range, from 1950 rpm to 5000 rpm. The optionally available Overboost feature briefly ups the torque peak to 505 lb.-ft. (685 Nm) from 2100 rpm to 4000 rpm. Power on tap, instantly Key to the turbocharged engine's potent efficiency is the use of variable turbine geometry (VTG). Essentially, VTG uses constantly adjustable turbine blades to vary the turbine's cross-section precisely to the exhaust flow regardless of engine load and/or speed. At low rpm, the blades close to form small air gaps. This causes the exhaust gases flowing through the small cross-section to accelerate, spinning the turbine quickly—as though it were a small, low rotating mass turbocharger. At higher rpm, with its inherently greater exhaust-gas flow, the turbine blades open, increasing their cross-sections and simultaneously lowering turbine speed, maintaining a constant intake charge pressure.