Which condition would result in no turbocharging?

• A. Waste gate fully open
• B. Waste gate fully closed
• C. Automatic control engaged
• D. Pressure relief valve open

Answer: (A)

When the wastegate is fully open, exhaust gas bypasses the turbine almost entirely. With little or no exhaust flowing through the turbine, the turbine can’t spin up the compressor, so the turbocharger can’t generate boost. In short, no turbocharging occurs because the wastegate is diverting exhaust away from the turbine.

If the wastegate were fully closed, almost all exhaust would pass through the turbine, causing high turbine speed and substantial boost—turbocharging would be active. If automatic control is engaged, the system modulates the wastegate to hold a target boost, so turbocharging still happens but at the intended level. If a pressure relief valve is open, excess pressure can be vented to prevent overboost, which reduces boost but doesn’t necessarily eliminate turbocharging entirely.