Abstract: A three-valve cylinder head system for a direct-injected spark-ignited (DISI) internal combustion engine. Two inlet ports are positioned in opposite quadrants of the cylinder head, with the fuel injector directing fuel spray into a third quadrant and the exhaust port being positioned in the fourth quadrant. A helicoid intake port and an axially directed intake port generate a swirl-type air flow in the piston cylinder without the aid of flow activation devices. The spark plug is positioned centrally adjacent the longitudinal axis of the cylinder bore. The piston has a bowl in its upper surface with an enlarged downstream area and a harbor area adjacent and past the spark plug which allow the swirl-type air flow to mix with the fuel spray and provide an appropriate fuel air mixture at the spark plug.

Abstract: An internal combustion engine cylinder head includes a pent roof (15) closing off a top of an engine cylinder (14) and first and second inclined surfaces (15a, 15b) intersecting an apex region (15c) of the pent roof. First and second air intake ports (20, 22) are formed in the pent roof surfaces and about respective first and second spiral axes (S1, S2) having respective radii (R1, R2, etc.) that change in magnitude and elevation as each air intake port approaches respective port entrances (20a, 22a) to the cylinder in a manner to provide air flows with in-cylinder air swirl in the same direction about the longitudinal axis of the cylinder.

Abstract: A piston-type, multicylinder internal combustion engine includes a cylinder block and a cylinder head mounted thereto, with a combustion chamber defined by the cylinder head and the top of the piston, with the engine being fueled by an an in-cylinder gasoline injection system which is centrally located with a spark plug such that the spark plug is closer to exhaust valves than is the injector, and with the injector being closer to the intake valves than the spark plug.