## FANDOM

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Bore is the diameter measurement of the cylinders in a piston engine.

Engine displacement is calculated by:

$\mbox{displacement} = {\pi\over 4} \times \mbox{bore}^2 \times \mbox{stroke} \times \mbox{number of cylinders}$

The term "bore" can also be applied to the bore of a locomotive stream cylinder and is the tern commonly used to define pipe size (but some types are specified by the external size designated by - OD).