Turbocharger - INGENIUM I4 2.0L Petrol - PHEV (G2748213): Operation: Notes

The turbocharger is an exhaust-driven centrifugal air compressor which increases power output by supplying compressed air to the engine. The turbine wheel of the turbocharger extracts energy from engine exhaust gases to drive the compressor wheel.

The purpose of the twin scroll turbine housing is to reduce the effect of exhaust events between the cylinders. When the exhaust valves first open a pressure pulse is released into the exhaust called the 'blowdown' pulse.

On a 4 cylinder engine, the 'blowdown' pulse occurs at a time when the previous cylinder in the engine cycle is still exhausting gas. The 'blowdown' pulse can therefore inhibit the exhaust process from the previous cylinder, increasing the amount of residual gas, increasing the tendency to knock.

The compressor wheel draws in ambient air through the air intake system which is compressed and delivered through a charge air cooler to the throttle body.

By turbocharging the engine, the pressure and density of the air entering the cylinders is increased, and therefore so is the amount of oxygen.

By turbocharging the engine the following benefits are enabled:

• Increased engine power output.
• Improving fuel consumption through engine downsizing.
• Ability to sustain power output at higher altitudes.

The turbocharger is interconnected by the charge air pipes of the intake air distribution and filtering system. For additional information, refer to: INTAKE AIR DISTRIBUTION AND FILTERING - INGENIUM I4 2.0L PETROL - PHEV

The charge air cooler is used to increase the density of air as it flows from the turbocharger compressor to the intake manifold. Compression of the charge air by the turbocharger raises the temperature of the air. The increased charge air temperature decreases its density, therefore less oxygen is able to fill the cylinders. This reduces the engine power. To overcome this, the compressed air is routed through the charge air cooler before it enters the engine. The charge air cooler reduces the compressed air temperature by transferring the heat to the low temperature engine coolant.

The operation of the turbocharger system is controlled by the PCM  . The turbocharger wastegate actuator controls the turbine inlet pressure, governing the pressure ratio across the compressor. The CRV prevents the compressor surge that would otherwise occur during quick throttle closing events.