Turbocharger - Diesel: Operation

Exhaust gases from the exhaust manifold enter the turbocharger's turbine housing and flow through the turbine blades. Exhaust flow and turbine speed increase as engine RPM increases. The impeller turns with the turbine and forces air into the intake manifold. The faster the impeller and turbine spin, the more pressurized air is provided for the engine.

To prevent engine damage, the wastegate opens when exhaust pressure exceeds a safe limit and allows exhaust gases to by-pass the compressor. A blow-off valve is used for protection in case the wastegate fails.

The blow-off valve, connected to the intake manifold, opens whenever boost pressure exceeds the safe limit. Excess boost pressure is vented to the intake pipe after the air cleaner. Some vehicles are equipped with a warning lamp which will light whenever the blow-off valve operates.

A boost pressure enrichment device is used to increase the amount of fuel delivered to the engine. As boost pressure increases the engines fuel requirements also increase. The boost pressure enrichment device ensures additional fuel requirements are met.