Until recently, cast iron and aluminum alloys havebeen the preferential materials used to manufacture most diesel and conventional gasoline-powered engine blocks. However, with a greater emphasis on increasing the efficiency of the engine via weight reduction, manufacturers have began to look for alternative alloys that are lighter than cast iron and aluminum alloys, while retaining the necessary strength to withstandthe forces of an engine. As of late, new manufacturing processes have been developed that have engendered two new alloys suitable for use in an engine block, magnesium alloy AMC-SC1 andcompacted graphite cast iron (CGI). In this paper, the functional requirements of the engine block, the processes used to manufacture the part, and the mechanical properties of the alloys will be discussed.