ENGINE

Provided is an engine (100), including: a cylinder including a cylinder liner; a piston provided inside the cylinder liner; a piston ring provided on the piston; a contact detector (184) configured to detect a contact between a step formed in an inner peripheral surface of the cylinder liner and the piston ring; and a compression ratio controller (182) configured to control a top dead center position of the piston so that the piston ring at the top dead center position is located on a combustion chamber side with respect to the step when the contact is detected.