ENGINE WITH WATER JACKET

A water jacket of an engine is capable of implementing cooling water flows as both a cross flow and a parallel flow. The water jacket includes a head water jacket formed in a cylinder head of an engine; a block water jacket formed in a cylinder block of the engine; and a variable partition wall which is configured to induce a cross flow of cooling water in a space between positions of cylinders in the head water jacket, where the variable partition wall has a shape configured to be varied according to an engine operating condition, and the variable partition wall allows the cooling water to flow in a selected one of the cross flow and a parallel flow according to the shape which is varied in head water jacket.