To what altitude will a turbocharged engine maintain sea level pressure?

A turbocharged engine is designed to maintain sea level pressure at higher altitudes than naturally aspirated engines can. The concept of critical altitude refers to the specific altitude at which a turbocharged engine can no longer maintain its designed manifold pressure, typically equivalent to sea level pressure.

At or below this critical altitude, the turbocharger effectively compensates for the decrease in ambient air pressure due to increased altitude, allowing the engine to function as if it were still at sea level. This is crucial for performance and efficiency, as it enables the engine to produce power more consistently, even as altitude increases.

Understanding this concept is vital for pilots and maintenance technicians, as it directly relates to engine performance and aircraft efficiency at varying altitudes. This is why, in this context, the correct answer is critical altitude.