Definition
In aviation maintenance and engine overhaul terminology, to cube an engine means to measure the displacement (cubic-inch volume) of its cylinders, or more broadly to determine the swept volume of a piston engine by calculation from bore and stroke. The term is also used informally to refer to the displacement value itself, expressed in cubic inches.
Plain English
To work out how much air-and-fuel space an engine's cylinders sweep through on each stroke, measured in cubic inches. The bigger the number, the bigger the engine.
Context Anchor
Seen in aviation math, aircraft performance discussions, maintenance calculations, and any place volume or a “cubed” value is used.
Derivation
From the geometric cube, because volume is calculated by multiplying three dimensions together (bore × bore × stroke, with a constant), producing a result in cubic units. To 'cube' an engine is to compute its cubic displacement.
Why Pilots Care
Engine displacement (the 'cubes') is a basic indicator of an engine's power potential. Pilots talking about a 'big-cube' engine are referring to large displacement, which generally means more horsepower and higher fuel burn.
Intuition Check
Do not read cube as just a box-shaped object. In calculations, cube usually means multiply the value by itself twice more, as in 4 × 4 × 4.
Example Sentence 1
After boring the cylinders oversize, the mechanic re-cubed the engine to confirm its new displacement.
Example Sentence 2
When planning a climb, the performance chart required cubing the rate-of-climb numbers for accurate fuel-burn projections.