Abstract: An installation for preheating the suction mixture of a carburetor internal combustion engine with a heat pipe extending from a place of the exhaust gas line system to a place of the suction pipe system and with a heat-absorption zone, on the one hand, and a heat emission zone on the other; the heat pipe leads from its heat-absorption zone to a lower part of the suction pipe directly adjoining the carburetor outlet and in its heat emission zone partly surrounds with its flat condenser jacket from below the flow channel of this pipe along a wall surface area while leaving free the main part of the pipe cross section.

Abstract: A four-cycle reciprocating-piston internal combustion engine having a main combustion chamber connected by a spill port with an unflushed ignition chamber. A fuel injection nozzle and a spark plug are arranged at the ignition chamber at angles with respect to one another. Fuel supply means are also provided at the main combustion chamber for supplying a substantial majority of the fuel consumed by the engine during operation. In order to maximize the effectiveness of the ignition chamber, while minimizing the high peak pressures, the ignition chamber and spill port are constructed so as to have an extensive homogenization of the fuel proportion injected into the ignition chamber. In preferred embodiments, the ratio of the volume of the ignition chamber to the total compression volume of the engine is in the range of 0.10 to 0.30 and the ratio of the volume of the spill port to the total compression volume is in the range of 0.01 to 0.25.