Diesel exhausts are approximately 1250°F (700°C), compared with gasoline engine exhaust · temperature of about 1850°F (1000°C). In

Diesel exhausts are approximately 1250°F (700°C), compared with gasoline engine exhaust temperature of about 1850°F (1000°C). In order to allow the turbine blades to adjust, rather than be fixed, Porsche engineers had to tame the demon heat by rethinking turbocharger design and materials. To ensure both high performance and a long, trouble-free service life, the turbo designers created turbochargers with adjustable turbine vanes and double redundancy cooling. In addition to the existing oil cooling for the turbo bearings, the turbo also has a water cooling system and a follow-up pump to keep the bearings temperatures under control. Regardless of turbo design, all turbocharged engines are subject to more stress than their naturally aspirated equivalents. Consequently, the 911 Turbo Cabriolet's engine is the same as the Turbo Coupe's. That means it is a liquid-cooled, flat, or horizontally opposed, six-cylinder with dual overhead camshafts, four valves per cylinder, variable valve lift and timing, distributorless solid- state ignition, sequential electronic fuel injection and twin turbochargers. The engine consists of a split, pressure-cast, light-alloy crankcase. The block is made in usual Porsche fashion with camshaft housing, cylinder head and cylinder housings bolted to the crankcase. Based on decades of Porsche racing success, the engine's lubrication system is a dry sump design, with the oil carried in a remote reservoir. This configuration permits a more compact engine, critical for superb road holding. To ensure more than adequate engine lubrication, the Turbo Cabriolet has nine separate oil pumps. There are two oil extraction pumps for the turbochargers, two oil extraction pumps on each cylinder head, and two oil extraction as well as one pressure pump in the crankcase. The extraction pumps ensure proper lubrication during long periods of hard braking. There are two oil coolers which transfer the heat from the engine oil to the engine coolant. The engine coolant itself releases its heat at three separate heat exchangers mounted in the front of the car. Radiators are mounted ahead of both front wheels in addition to one mounted in the car's nose. The crankshaft spins in eight main bearings. The six forged light-alloy pistons pump in Nikasil®- coated cylinder liners. The 3600 cc displacement engine is a highly responsive short-stroke design, with a cylinder bore of 100 mm (3.94 inches) and piston stroke of 76.4 mm (3.01 inches). There are four valves (two intake, two exhaust) per cylinder operated by dual overhead camshafts. Fuel injection is electronic and under the purview of the Digital Motor Electronics control module, as is the distributorless solid-state ignition system, which boasts individual coils for each cylinder. Two different camshaft profiles The DME also controls valve action via Porsche VariCam Plus. This valve management system adjusts intake valve lift and timing based on engine speed and load. Though the VarioCam Plus operates far too quickly for the driver to be aware of it, the results are obvious. The effect is that of an engine with two different intake camshaft profiles, one set up for smooth and efficient around-town driving, the other a high-performance camshaft designed for higher speed. These two designs usually each preclude the other and most cars have a compromise of the two. Porsche VarioCam Plus removes the compromise and the driver benefits from the best of both driving worlds.