Engine Performance: System: Turbocharger: Operation

At idle and light throttle, the Turbo engine operates like a standard engine. When more power is required, exhaust gases from exhaust manifold enter the turbocharger's turbine housing and flow through the turbine blades.

Exhaust flow and turbine speed increase as throttle opens and RPM increases. The impeller turns with turbine and forces air into compressor housing and intake manifold. As impeller and turbine speed increases, boost pressure also increases.

If boost pressure exceeds safe limits, engine damage may result. The wastegate opens when exhaust pressure exceeds a predetermined limit and allows exhaust gases to by-pass compressor. A boost pressure safety switch is used for protection in case wastegate fails. This switch is connected to the intake manifold and serves as ground for electric fuel pump. When pressure is higher than 11.6 psi (.82 kg/cm² ), the switch opens and the fuel pump stops, slowing the engine.

An electric blower fan is used to cool the injectors and intake manifold and prevent vapor lock. A thermal switch controls fan operation and turns the fan on whenever manifold temperatures exceed 212°F (100°C).

Turbocharger operation requires a large quantity of clean oil to prevent bearing failure. Turbo models have increased oil capacity, an oil cooler, oil thermostat, and special filter. Both turbocharger filter and regular engine filter should be changed at regular intervals.