Cylinder liner for motorcycle engines made of aluminum powder metallurgy composites, P.M.C., have been developed with powder-extrusion techniques through a joint project with HONDA R&D Co., Ltd. This P.M.C. is consisted of rapidly solidified powder comprised of Al-17Si-5Fe-3.5Cu-1Mg-0.5Mn with fine spherical alumina particles and fine graphite powder additives, which has excellent wear resistance equivalent to the gray cast iron in used with both piston and piston ring. It is considered that the uniformly dispersed fine alumina particles and graphite powders in the matrix improve the tribological properties, Furthermore, the hardness was not decreased by the thermal history during the die casting process compared with the conventional casting aluminum alloy such as A390. This alloy also has good machinability, that is, the tool wear is almost equivalent to the conventional gray cast iron. This P.M.C. has been applied to the cylinder liner for automotive engines.