Actually, it is even worse than that - an automatic waste gate will close if manifold pressure is lost, increasing back pressure. I would estimate that the high back pressure with no boost will subtract at least 10% power. The high back pressure will also reduce the volumetric efficiency of the engine for perhaps another 5% loss. That would make the sea level go-round roughly equivalent to a naturally-aspirated engine running at 25 inches MAP or less. Not a good thing, for
sure.
Gary Casey
An turbo charged engine that loses upper deck is NOT a naturally aspirated engine. A turbocharged TSIO 550 develops 100% takeoff power at 38.5 inches and 2700 RPM. If you lose a hose coupling at sea level the most you might get out of this engine is 29 inches-- making a go around rather interesting.engiengine just becomes a naturally
aspirated IO550.