In the intake advancement control, combustibility is improved by increasing the actual compression ratio and increasing the compression end temperature.

In the late stage of the compression stroke of the cylinder (2), diffusion of the flammable mixture is suppressed with squishes.

The pressure at the end of compression is about 10 bar.

Squish areas are preferably provided around the periphery of combustion chamber (12).

The acquisition unit obtains a parameter relating to a compression end pressure in a cylinder of the engine.

It is arranged that in the terminal period of compression stroke, the tumble flow (T) and squish flow (S) are produced in opposed relationship to each other.

Squish areas are preferably provided between each pair of adjacent valves around the combustion chamber perpiphery.