FAA Powerplant Written Practice Test

What happens when the turbocharger waste gate is completely closed?

1. Exhaust gases bypass the turbine

2. All exhaust gases go through the turbine

3. Turbocharger will shut down

4. Engine will run at idle

The correct answer is: All exhaust gases go through the turbine

When the turbocharger waste gate is completely closed, all exhaust gases are directed through the turbine. This is crucial because the turbine extracts energy from the exhaust gases to drive the compressor, which increases the intake air pressure. A fully closed waste gate allows for maximum exhaust gas flow to the turbine, enhancing the turbocharger’s ability to generate boost pressure. This scenario typically occurs during periods of full throttle when the engine needs maximum power, ensuring optimal performance. In contrast, if the waste gate were partially or completely open, some exhaust gases would bypass the turbine, reducing boost and overall performance. It's important to understand that the turbocharger is designed to work efficiently under various operating conditions, and the waste gate plays a key role in managing the flow of exhaust gases accordingly.