Fuel injected internal combustion engine with reduced squish factor

摘要

A direct fuel injection internal combustion engine configured to reduce engine knock during high speed operation of the engine is provided. The engine comprises a cylinder head including a lower surface portion closing an upper end of a cylinder to define a combustion chamber between a piston upper surface and the cylinder head lower surface portion. The lower surface portion has therein an upwardly extending recess. The recess has a lower end which is complementary with the piston surface and an upper end. The lower end of said recess has an area in a plane perpendicular to a longitudinal axis of the cylinder and that area comprises a range from more than 20% to about 65% of the cross-sectional area of the cylinder.