Piston for an internal combustion engine and engine provided therewith

The piston (5), designed to perform a sliding reciprocating motion inside and i.c. engine cylinder bore (3), has a cavity (26) in its upper face (27) that forms part of the cylinder's combustion chamber. The cavity has a grooved surface (30) that allows modification of a fluid flow in contact with it. The groove can lie in one or two perpendicular directions and have a V, L or U-shaped cross-section, with the ratio of the depth of the grooves to their spacing being between 0.1 and 1 : 1. They can also lie in a limited number of spirals.