Engine Performance: System: Turbocharger: Description
Most models use a water-cooled turbocharger, mounted directly to the exhaust manifold with a wastegate assembly attached to rear of turbine housing. The turbocharger consists of a turbine/compressor assembly, oil supply system and wastegate. Other components include impellers, impeller shaft, bearings and impeller housings.
The safety valve of the system is a pressure actuated wastegate that prevents excessive intake boost pressure. On Saab models, additional engine protection is provided by the Automatic Performance Control (APC) system. The APC system senses engine knock and automatically cuts back the amount of boost.
Turbocharger operation requires a large quantity of clean oil to prevent bearing failure. Engine oil pressure provides constant lubrication to the system.