Turbocharging System: Operation

Air enters through the air filter and is mixed with fuel in the carburetor. The air/fuel mixture passes into the compressor assembly and into the intake manifold. When the engine is operating at low RPM, the compressor does not affect normal engine operation. As RPM increases, the flow of exhaust gas increases and speeds up the turbine assembly mounted in the exhaust system. Since the turbine is directly connected to the compressor, it begins to turn faster and force air into the engine. Since more fuel/air mixture is forced into the engine, power output is increased.

Greater exhaust flow produces more compression of intake mixture, resulting in a cycle that would destroy the engine if there were no way to limit it. The wastegate assembly senses the amount of mixture compression (boost) and vents exhaust gases around the turbine when boost reaches a predetermined level. This action is absolutely necessary to maintain engine life, and should any problem occur that causes over-boost or high engine oil temperature, the driver will be signaled by a warning light and buzzer.

The higher combustion chamber pressures developed in a turbocharging system create problems with detonation. To prevent engine damage, Ford's system is designed to retard engine timing 6 degrees when boost pressure reaches 1 psi, and another 6 degrees at 4 psi. The maximum boost permitted by the wastegate system is 6 psi.

The increased engine load requires a more extensive oil supply system. Capacity and oil pressure are increased in the turbocharged engine. The compressor assembly can reach speeds of 140, 000 RPM, and lubrication is essential to prevent self-destruction of the compressor. Whenever any kind of engine work that involves disassembly of components is done, or turbocharger disassembly, engine oil and filter should be changed.