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Porsche V8: The Knowledge
Debuting in the all-new Panamera, Porsche's latest generation V8 engine is packed with technical features to ensure that targets for fuel consumption, emissions and performance were all achieved
Porsche has unveiled details of its all-new V8 powerplant, which is to debut in the 2017MY Panamera. Key development goals were maximum efficiency and extraordinary performance. In addition, the new engine line-up will exhibit a flexible structure with modular components, so that other variants such as hybrid versions can be implemented.
The Panamera Turbo will initially have the most powerful V8 petrol engine of the new engine generation. Its 4.0-litre engine develops between 5,750 and 6,000rpm and reaches a peak power of 557ps. Its maximum torque of 770Nm is available between 1,960 and 4,500rpm, helping the car achieve a top speed of 306 km/h. These figures stand in contrast to a claimed improvement of up to 1.1l/100 km in its combined fuel consumption of 9.4 – 9.3 l/100 km (New European Driving Cycle or NEDC); this equates to CO2 emissions of 214 – 212 g/km.
The new eight-cylinder engines have a longitudinally-mounted V-engine design with a cylinder bank angle of 90°. The four intake and exhaust camshafts can each be adjusted 50° and are chain driven. The displacement of the four valve per cylinder engine that can rev up to 6,800 rpm is 3,996 cc. The bore and stroke are both 86 mm for a quadratic ratio. Key technical characteristics Porsche is keen to highlight on the new V8 twin-turbo direct petrol injection engines include its new charging concept (central turbo layout), injectors located centrally in the combustion chamber, nearly wear-free coating of the cylinder linings and cylinder deactivation. Using the Panamera Turbo as an example, this has allowed peak power to increased by 30hp and torque by 70Nm, in addition to its fuel economy improving by 10%.
The Panamera Turbo has the first Porsche engine to be equipped with a new adaptive cylinder control system. The system makes the eight-cylinder engine a four-cylinder engine in part-load operation: temporarily and imperceptible to the driver. The results: fuel economy has been improved by up to 30% in the four-cylinder phases, depending on power demand. Deactivation and reactivation of the cylinders are controlled by a two-stage sliding cam system. In this process, the intake and exhaust cam adjusters on the camshafts for cylinders two, three, five and eight are deactivated or reactivated as necessary. The intake and exhaust valves of these cylinders are completely shut down in four-cylinder operation. Cylinder deactivation is operational over an engine speed range from 950 to 3,500 rpm and up to a torque limit of 250Nm.
A high-priority aspect during development of the eight-cylinder engine for Porsche was its compact construction; the aluminium engines are also up to 9.5kg lighter than their predecessors. The weight reduction was achieved by various design measures. For instance, the high-strength aluminium cylinder crankcase with its bearing cover weighs just 39.1kg; represents a weight reduction of 6.7kg compared to the comparable 4.8-litre engine of the previous model.
The methodic approach to weight loss extends to the crankshaft. Porsche reduced its weight by 1.4kg. The new crankcase drive with its crankshaft supported by five bearings is another element of compact engine design. The crankshaft drive is distinguished by the use of an intermediate shaft that is used to drive the water pump and the timing drive; thanks to the toothed gear drive of the water pump being inside the engine, Porsche was able to compress the engine package and reduce friction power losses. Also having a positive influence on mounting space and weight are the central turbo layout and a 0.8-litre reduction in engine displacement.
15 July 2016