Combustion chamber assembly for an engine

The axial center line of the inlet valve is inclined and the distance between the piston crown surface and the portion forming part of the lower surface of the valve head of the intake valve at least in the nearby of the crankshaft axis side is increased in accordance with the approach of the crankshaft axis. The relationship G2> G1 is met. In this case, G1 is the minimum distance between the lower surface of the cylinder head, which is disposed between the intake valve and the side opposite to the inlet valve exhaust valve with intermediate crankshaft axis and the piston crown surface at top dead center and G2 is subject to the different distances between the bottom surface of the valve head of the intake valves and the piston crown surface is achieved for the smallest distance from the crankshaft axis in the stroke center of the overlap when inlet valve and outlet valve are opened simultaneously.