Is turbocharging active when the waste gate is fully closed?

• A. Yes
• B. No
• C. It depends on RPM
• D. Only at max throttle

Answer: (A)

The wastegate determines how much exhaust energy is sent to the turbine. When it is fully closed, nearly all exhaust flow goes through the turbine, spinning it up and driving the compressor to pressurize the intake air. That is the essence of turbocharging—using exhaust energy to boost air pressure in the engine. So, as long as the engine is producing exhaust flow, the turbocharger is active, and closing the wastegate maximizes that activity. The boost level will vary with engine speed and exhaust volume, but the turbo is still doing its job when the gate is closed, not inactive or restricted to only at full throttle.