Abstract: A method for improving the operation of an engine including a cylinder space, a piston movable therein, at least one inlet valve having an inlet duct associated therewith, and at least one outlet valve having an outlet duct associated therewith includes providing an air filling in the inlet duct upstream of the inlet valve(s). An initial portion of the air filling is introduced into the cylinder space while the outlet valve(s) is open, whereby the initial portion of air filling flushes the cylinder space and exits into the outlet duct through the open outlet valve(s). Upon closing of the outlet valve(s) the introduction of the air filling into the cylinder space is continued and thereafter an air-and-fuel mixture is brought into the cylinder space through the same inlet duct(s) and inlet valve(s) through which the air filling has passed in being introduced into the cylinder, resulting in a fuel charge stratified a top of the retained air filling.