Abstract: The combustion engine forms "squish" spaces between the piston and the cylinder head and has additional guide means in the combustion chamber which create a rotational flow in the combustion chamber. The floor of the combustion chamber is formed by a trough-shaped recess in the piston head, so that it forms a "squish" space extending over the complete width of the combustion chamber. In the area between the valves, a further, central "squish" space extends which, in conjunction with the wall of the cylinder head which is situated above it, forms a further "squish" space flow which reinforces the lateral "squish" space flow. In this way the ignition timing can be further retarded and the temperature peak reduced together with an additional reduction in emissions of oxides of nitrogen. A very weak mixture with an excess of air of 30% or more can be ignited which likewise maintains a low burning temperature thus producing less nitrous oxide.