Abstract: The Process Chamber Motor PKM is a combustion piston engine comprising a Process Chamber as a novel type of prechamber, into which fluid fuel continually flows and is processed therein over a plurality of cycles to form a PKM-combustible-material. Above the Compression Chamber—separated by an impermeable Separating Wall—lies a Process Chamber PK, into which fuel is pushed over a long period (gear pump), therein vaporizing and therein being processed with added oxygen-overstoichiometric gas to form combustible material: gas, possibly with smoke and soot. The PK contains combustible material for at least two cycles, sustained at a pressure near the maximum attained above the piston and sustained at Process-temperature (e.g. 800° C.). The portion of combustible material to be combusted in the respective cycle streams—via a valve (e.g. pneumatically-actuated Cylinder-Valve) which is opened in the culmination zone—into the Combustion Chamber.