One exemplary embodiment of the present disclosure relates to an engine intake port structure. According to the engine intake port structure of the exemplary embodiment of the present disclosure, a chamfer is formed to be offset to either side from an end corner of an intake port. Accordingly, the inflow of a fuel gas is concentrated on a side in which an opening width of the chamfer is wide at the beginning of an opening stage when the intake port is opened/closed by a valve unit, and after the intake port is opened, the opening width is formed to be similar at four sides of the valve unit such that swirls formed in the fuel gas is weakened. That is, complete combustion of the fuel can be anticipated since the length of time during which the fuel gas remains in a combustion chamber is extended.

A compression ignited combustion engine has at least one cylinder and first and second gas intake ports in a cylinder head restricting a combustion chamber. One gas intake passage leads to the two ports and is widened in a Y-shaped end influencing gas entering each port into a tangential flow in opposite direction with respect to the flow into the other port. The first intake port is designed to allow gas entering this port to continue said tangential flow so as to enter the combustion chamber in a swirl in a first rotation direction, whereas the second intake port is designed to guide gas entering this port to also enter the combustion chamber in a swirl in said first rotation direction.

A compression ignited combustion engine has at least one cylinder and first and second gas intake ports in a cylinder head restricting a combustion chamber. One gas intake passage leads to the two ports and is widened in a Y-shaped end influencing gas entering each port into a tangential flow in opposite direction with respect to the flow into the other port. The first intake port is designed to allow gas entering this port to continue said tangential flow so as to enter the combustion chamber in a swirl in a first rotation direction, whereas the second intake port is designed to guide gas entering this port to also enter the combustion chamber in a swirl in said first rotation direction.