Pistons

Pistons







The mixture formation and combustion processes for direct fuel injection (DFI) require a new piston crown shape. This was adapted in the new 911 Turbo to increase the compression ratio from 9.0:1 to 9.8:1 and to therefore also improve the engine efficiency.







Like in the previous model, forged aluminum pistons are used to reliably achieve the high performance values of the new engine. Piston ring design details were optimized to minimize frictional losses and the first ring was additionally provided with a high-quality coating. As a contribution to increasing the displacement from 3.6 l to 3.8 l, the piston diameter of the new 911 Turbo was increased from 100 mm to 102 mm and the piston stroke from 76.4 mm to 77.5 mm.

To reduce the lateral forces and ensure reliable transmission of the enormous gas forces from the piston to the crankshaft, the connecting rod was lengthened from 127 mm to 140 mm compared with the previous model and its overall shape modified.

A computer-optimized design of pistons and connecting rod in combination with a short compression height permits the components to be designed with an optimum power-to-weight ratio. The low mass forces bring about a reduction in the crank drive loads and a further increase in the smooth running of the new 911 engines.

The high-grade coating of the first piston ring is a DLC coating. (DLC = Diamond-Like Carbon; a coating technology used, for example, for high-performance cutting tools for machining metal; it is an amorphous carbon layer with outstanding anti-friction and wear properties).

Piston Cooling







The piston crown temperature in the 911 Turbo engines is reduced by means of piston injection cooling. The spray nozzles are pressed in the crankcase. To ensure the necessary engine oil pressure at low rpm and high engine oil temperatures, these spray nozzles open at 26 psi (1.8 bar).