Variable compression ratio piston - has outer part telescopically mounted on upper end of inner part

An upper hydraulic chamber is formed between the ends of the inner and outer members. A lower chamber is fluidly connected to the upper chamber and disposed adjacent the piston ring area of the piston assembly. Both a lubricant supply passage and a discharge passage are formed through the piston inner member and are fluidly connected with the upper chamber. Both the supply inlet valve and the discharge valve are contained within a single housing and, together with the housing, form a valve assembly. The valve assembly in turn is slidable within a bore in the upper end of the inner member and locked into position by a snap ring.