Engine Performance: System: Turbocharger: Description

The 900 Turbo uses the Garret Turbocharger. See Figure Exhaust gases drive the turbine, which turns the compressor forwarding air under pressure to the throttle valve.

Excessive pressures are controlled by a boost pressure control valve or wastegate. A back-up safety device, a pressure switch, prevents engine damage in case there is failure of the wastegate. 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 turbo boost.

The 900 Turbo is designed to operate at low engine speeds to provide increased torque at typical vehicle driving speeds. The turbine shaft is mounted in a floating, sliding-contact bearing having a high oil flow. The shaft actually floats on oil during operation.

Lubrication is supplied by the engine lubrication system. The shaft is sealed against bearing housings with sealing rings installed in shaft grooves.