Factors Affecting Piston Ring Life and Performance in Small Two and Four Cycle Engines

This paper illustrates the fact that optimum piston ring performance depends not only on characteristics of the ring but also on techniques and materials required to create compatability between rings and the bore surfaces on which they work. Basic requirements and considerations in ring design and machining such as shape, tension, and finishes are outlined. In recent years, piston rings have been modified to work satisfactorily in cast iron, aluminum, and chromium plated bore surfaces. Ring and cylinder problems such as bore porosity, poor cylinder finish, metallurgy of cast iron bores, and dirt are discussed.