Powdered metal cylinder liners

A cylinder liner for use in an internal combustion engine having a cylinder block with a cylinder bore adapted to carry a piston therein, the liner comprising:

• a body formed from a powdered metal material, the body formed therefrom being rigid and wear resistant, the body comprising:
• a smooth, inner, piston-directing surface;
• an outer, cylinder bore-contacting surface;
• and
• an upper, combustion containing area;
• means for improving transfer of heat from the combustion containing area to the cylinder block, wherein the heat transfer improving means comprises an isostatically formed, rough surface finish extending about the outer, cylinder bore-contacting surface, the surface finish having micropores dispersed therein, wherein the rough surface finish and micropores promote a substantially complete metal-to-metal bond between the body and the cylinder bore, and wherein the rough surface finish further promotes a mechanical, interlocking bond between the body and the cylinder bore;
• and
• means, disposed within the piston-directing surface, for improving piston ring and piston scuff resistance while maintaining piston-directing surface smoothness, wherein the scuff resistance improving means comprises a plurality of pores distributed throughout the piston-directing surface, the pores having a size sufficient to hold an amount of lubricant to form a substantially continuous, smooth glide path between the piston/piston ring and the inner, piston-directing surface.