Method for producing a housing casing for a rotary piston internal combustion engine

A method for manufacturing a housing casing for a rotary piston internal combustion engine, especially of trochoidal construction, as well as the housing casing made according to this method, whereby the housing casing consists of light metal whose internal running surface for the piston consists of a coating of hard material; the method thereby involves leaving during the machining of the inner wall of the housing casing a material island of such light metal about the discharge opening of the already bored or still to be bored spark-plug-firing channel, whose height corresponds at least to the thickness of the coating to be subsequently provided along the inner contour of the housing casing in the finish-machined condition; as a result thereof the area of the discharge opening of the firing channel is constituted exclusively of such light metal.