An internal combustion engine includes a piston adapted to reciprocate in
a cylinder. The piston includes a first portion, a second portion, and a
third portion. The first portion of the piston forms a crown surface of
the piston, the second portion of the piston forms a piston ring groove
of the piston with the piston ring groove arranged and configured to
receive a piston ring, and the third portion of the piston forms a
crankcase side surface of the piston with the crankcase side surface
facing a crankcase of the engine. The second portion of the piston is
formed of a material having a higher thermal conductivity than a material
forming the first portion of the piston and a material forming a third
portion of the piston.