formed with an interior cylindrical surface 48 which is bisected at a point below its upper surface 50 by a connecting rod pin 20 for receiving and securing the upper end 22 of a connecting rod 24 the interior cylindrical surface 48 of piston body 40 is further formed with an interior annular groove 52 which is formed proximate the upper portion of piston body 40 interior annular groove 52 will seat an annular portion of a locking ring 54 the ceramic or ceramic composite piston head 60 is formed of a ceramic or ceramic composite material which has a low coefficient of heat transmission ceramic or ceramic composite piston head 60 may be formed with a planar orientation a wedge orientation or hemispherical orientation the ceramic or ceramic composite piston head 60 has an outer circumference 62 complimentary with the circumference of the piston body 40 extending downwardly from the lower surface 64 of the ceramic or ceramic composite piston head 60 is a cylindrical member 66 whose circumference is substantially identical with the inner circumference of piston body 40 cylindrical member 66 may be in the form of a solid disk or it may be annular in configuration having its own outer and inner side walls cylindrical member 66 is designed to be inserted into the.