FAA Powerplant Written Practice Test

Which component regulates the speed of a turbocharger?

1. Throttle valve

2. Boost controller

3. Waste gate

4. Fuel pump

The correct answer is: Waste gate

The component that regulates the speed of a turbocharger is the waste gate. The waste gate is a crucial part of a turbocharged engine's system. Its primary function is to control the pressure and flow of exhaust gases that enter the turbine side of the turbocharger. When the engine reaches a predetermined boost level, the waste gate opens, allowing some of the exhaust gases to bypass the turbine. By doing this, the waste gate prevents the turbocharger from producing excessive boost, which could lead to engine damage or inefficiency. This regulation of exhaust flow helps maintain optimal turbocharger speed, ensuring that the engine operates within its designed parameters. Other components such as the throttle valve, boost controller, and fuel pump play different roles in the engine operation. The throttle valve controls the intake air volume, the boost controller determines the desired boost pressure and potentially modulates the waste gate, while the fuel pump supplies fuel to the engine. However, it is the waste gate that directly manages turbocharger speed by controlling the exhaust flow that drives the turbine.