Porsche 911 GT3 Details

Press Release

Lighter components reduce rotating masses Pistons are lightened – by nearly an ounce per piston – through the use of shorter piston jackets. Piston pins are made of a new, high-strength material that reduces weight by another .9 ounce per cylinder. Titanium connecting rods have been lengthened, but precision forging and shot-peening reduces their weight by .075 ounces each. These pistons and connecting rods run so smoothly that no vibration dampers are needed on the crankshaft. This saves nearly another five pounds in rotating masses. The crankshaft rides on eight bearings and has a plasma-nitrided finish that enhances its strength and stability. Every moving component in the cylinder charge cycle was evaluated in pursuit of weight reduction. Lighter valvetrain allows higher revs Porsche engineers were able to reduce the weight of the 2004 Porsche 911 GT3’s valves by 19 percent. Intake and exhaust valves have a dome-shaped profile. They also are .2 inches smaller in diameter. Valve tappets are specially hardened through carbon-nitriding and the tappets also have a new ball-shaped bottom profile. These new tappets reduce valvetrain weight by more than a pound. Meanwhile, the engine’s intake and exhaust cams have sharper contours. The new tappets and cams allow for more rapid valve opening and higher valve lift. Double valve springs assure proper valve closure. Friction between the various parts of the valvetrain has been reduced and therefore less oil flow is necessary for lubrication. VarioCam provides power, fuel economy and emission control As with other Porsches, the GT3’s engine benefits from Porsche VarioCam technology. VarioCam is an intake camshaft adjustment system that modifies valve timing to provide maximized power while enhancing fuel economy. The GT3 uses the latest, infinitely variable VarioCam technology to achieve the finest tuning of engine characteristics including power, torque and emission management. Fuel economy and emissions are further enhanced by the engine’s ME 7.8 management system that features “E-gas� technology. The gas pedal and throttle butterfly are separate, which helps optimize both fuel consumption and emissions without any effect on the engine’s immediate response to the driver’s commands. Performance-oriented air systems The GT3 engine draws its air through an air filter but without needing an intake funnel. The intake manifold, which is made of light alloy, operates in two stages: A resonance flap remains closed in the 2,500 - 5,500 rpm range to provide high torque. Beyond the 5,500 rpm, the resonance ace flap is open in the interest of maximum horsepower. The exhaust system is basically the same as on the 911 Carrera, so it features a twin-chamber design with exhaust gas from the left- and right-hand cylinders flowing separately through a lambda control oxygen sensor to the catalytic converter. Motorsports-style engine design Porsche uses the GT3 engine to homologate the engines it uses in international motorsports competition. Because of the need in racing to make changes very quickly, often in response to changes in regulations concerning engine displacement limits, the cylinder housing, cylinder head and crankshaft housing are combined into a single unit for the three cylinders on either side of the crankshaft. This also increases the engine’s torsional stiffness. Cylinder liners for the GT3 engine are made from a light alloy of aluminum coated with Nikasil. The cylinder heads are made of extremely temperature-resistant light alloy. The GT3 engine also features dry-sump lubrication. With its oil tank separate from the engine, a dry-sump system can provide optimum lubrication even with the extreme application of brakes used in racing. For the GT3, five oil pumps are used to provide the needed lubrication. Six-speed manual transmission As a car intended for true enthusiast drivers, the 2004 Porsche 911 GT3 is equipped with a six-speed manual transmission. At 1.00 (fifth) and 0.85 (sixth), the last two gears have somewhat shorter ratios than the first-generation version. Also updated are the synchronizing rings for third, fourth and fifth gears, which are now made of steel instead of brass. These new steel rings guarantee precise shifts while increasing strength and service life by a factor of 10. The gearbox also features splash oil lubrication and new external fluid cooling, similar to those used by Porsche racecars. A pump extracts the hot oil and sends it through an oil/water heat exchanger. After such cooling, the transmission fluid is sprayed as required on the individual gears, allowing more precise application to avoid “critical� temperatures in the gearbox. Reinforced body The 2004 Porsche 911 GT3 shares much of its body panels with the Porsche 911 Carrera 4S. However, the GT3’s body is reinforced to meet the demands it may face on the racetrack. These reinforcements provide both enhanced passive safety and also increase torsional stability by 25 percent. This stiffer chassis provides a platform for the car’s suspension to perform as designed and engineered.