Engine 9111 · 1570 Cylinder head 15 Chain drive

Engine 9111 1570 Cylinder head 15 Chain drive The introduction of VarioCam Plus A separate intake and exhaust camshaft is necessitated a new design of the cylinder used for each cylinder bank. These head and the camshaft control. camshafts are driven directly by a double As in the previous model the cylinder head roller chain. The chains are guided by is in three parts, consisting of basic plastic guide rails and hydraulic chain cylinder head, bucket tappet guide housing tensioners located at the untensioned end and cylinder head cover. The oil protection of the chain. tubes are now part of the bucket tappet The intake camshafts in the new 911 guide housing and are sealed at the Carrera also have a valve stroke control on cylinder head cover side with fitted sealing the intake side in addition to the VarioCam rings. Plus system (the system is described in a The valve springs of the exhaust valves are separate section). The respective solenoid single valve springs and of tapered design, valves are fitted in the cylinder head. the intake valves are designed as a double This optimises the compromise between valve spring set due to the increased forces. maximum power output and maximum For immediate lubrication of tappets when torque while simultaneously reducing fuel starting engine, the bucket tappet housing consumption and improving running is provided with oil chambers on the intake smoothness of the engine. side. A driving flange for the oil suction pump is attached on the input side of each exhaust camshaft.1571 Cylinder head gasket The multi-layer steel gasket is covered with 1505 Camshafts high-temperature-resistant plastic in order to enhance the sealing quality of its The camshafts are hard-chilled components surface. and hollow-cast to reduce weight. The The advantage of this steel gasket is that shank diameter of all camshafts is 26 mm. heat can be dissipated from the cylinder The intake valve stroke is variable (3.0 mm head very efficiently. or 10.0 mm). 1_12_02 1 - 6 Service Information 2002