A piston for an internal combustion engine has an upper crown with a top and a bottom surface, and a lower crown with a top and a bottom surface. The upper crown and the lower crown are fixedly attached to each other using welds, with the bottom surface of the upper crown and the top surface of the lower crown forming a mating surface. The piston also has at least one centrally located air gap formed on the mating surface. The air gap is sealed to prevent substantial airflow into or out of the air gap.
U.S. GOVERNMENT RIGHTS
This invention was made with government support under the terms of Contract No. DE-FC05-00OR22806 awarded by the Department of Energy. The government may have certain rights in this invention.