A valve for an engine cylinder includes a head. The valve is selectively moveable between a closed position in which the head blocks a port and an open position in which the head unblocks the port. A lower stem is formed as one-piece with the head, and a thermal cavity formed within the lower stem. The thermal cavity is at least partially filled with a heat transfer medium. An upper stem is attached to the lower stem opposite the head. A thermal barrier is located adjacent a junction of the lower stem and the upper stem.