Air intake system for an internal combustion engine

A single admission conduit (1) connects the cylinder head (7) to the cylinder admission zone through an admission valve. The admission conduit opening which discharges into the cylinder (3) is located so that the straight line (D1) joining the center of the opening to the cylinder center makes an angle between 0o and 60o with the straight line passing through the cylinder center and parallel to the face opposite the cylinder head. The conduit is divided into two parts by an internal separation wall (5) and has sealing valve (6) which can be progressively adjusted.