Plain English Meaning

Pushing a turbocharged or supercharged engine harder than it is designed to handle, so that the air pressure being forced into the cylinders exceeds the published limit.

Full Definition

A condition in which a turbocharged or supercharged engine is operated at a manifold pressure higher than the maximum allowed by the manufacturer. Overboost can cause detonation, excessive cylinder pressures, and serious internal engine damage.

Context Anchor

You may see this term when learning about high-performance piston engines, takeoff power settings, and engine operating limits.

Derivation

Combines the prefix '-' (beyond, excessive) with '' — the term used for the extra manifold pressure produced by a or above . So 'overboost' literally means boosting beyond the amount.