Abstract: A toroidal chamber in a piston communicating through an orifice at a top face of the piston located in an internal combustion system, such as a spark ignition engine or a compression ignition engine. The chamber arranged to receive a fuel/air mixture so that a flame front, propagated in a main combustion chamber outside the toroidal chamber reaches the toroidal chamber, the fuel in the toroidal chamber burns. The burning creates pressure in the chamber that exceeds the pressure in the main combustion chamber. The combustion gas of high pressure is jetted out of the toroidal chamber into the main combustion chamber. The high pressure combustion gas jet generates turbulence and mixing in the main combustion chamber, contributing to an improved combustion. Accordingly, the power output and the thermal efficiency of the internal combustion system is improved.