FAA Powerplant Written Practice Test

What happens to exhaust gases when the turbocharger waste gate is completely closed?

1. All the exhaust gases are directed through the turbine

2. Some exhaust gases are bypassed

3. Exhaust gases are vented outside the engine

4. All exhaust gases are recirculated

The correct answer is: All the exhaust gases are directed through the turbine

When the turbocharger waste gate is completely closed, all exhaust gases are directed through the turbine. This is because the waste gate acts as a valve that controls the flow of exhaust gases entering the turbocharger. When it closes, it prevents any exhaust gases from bypassing the turbine section. In this state, the turbocharger maintains a higher exhaust pressure, which allows for greater acceleration of the turbine and consequently increases the amount of compressed air entering the engine. This can enhance engine performance by providing more power and improving efficiency, allowing for better combustion of the fuel when there is a demand for it. In contrast, if the waste gate were partially or fully open, some exhaust gases would be bypassed, reducing the effectiveness of the turbocharger. Therefore, the operation of the waste gate has a crucial role in managing the turbocharger's performance and the engine's overall power output.