Turbocharger: Description and Operation

Turbocharger System:

TURBOCHARGERS
The turbochargers (2) are mounted on each exhaust manifold. Each turbocharger functions as an exhaust driven air compressor. Exhaust from the engine is routed past a turbine wheel, causing it to spin. Attached to the turbine shaft is an impeller wheel. Intake air is drawn through the other side of the turbocharger and as exhaust flow rises, the air is compressed and then forced into the engine at higher pressure. The increase in pressure causes a denser air charge entering the engine. With the denser air more fuel must be added to maintain the stoichiometric ratio. Because more air and fuel are loaded into each cylinder, more power is derived from each firing of the cylinder.

Wastegate Operation:

WASTEGATE OPERATION
Because there is the potential for too much pressure being delivered to the engine, a wastegate is used. The wastegate is controlled by a spring loaded diaphragm. Pressure is applied to the diaphragm by means of a crossover pipe connected to the engine intake side of the turbocharger. When pressure exceeds that of the spring, the diaphragm pushes open a door (gate) in the turbocharger allowing some of the exhaust flow to divert past the turbine wheel. With some of the exhaust flowing directly into the exhaust pipe, the turbine slows, lowering boost pressure to acceptable levels.

Solenoid Valve:

WASTEGATE SOLENOID
Wastegate operation is controlled by the ECU in order to provide maximum engine performance. If no engine detonation is detected, the wastegate solenoid is energized by the ECU. When powered, the solenoid connects the wastegate diaphragm to the intake side of the turbocharger, causing high boost. If detonation is detected the solenoid is deenergized which connects the wastegate diaphragm to the outlet side of the turbo allowing the wastegate to open and lower boost pressure.

Intercooler:

INTERCOOLERS
The intercoolers (2) are mounted under each front corner of the vehicle. They function as air radiators, cooling the compressed air from the turbochargers before the air enters the engine. The cooling of the air causes it to become denser and able to combine with an additional amount of fuel.