Evaluation of Two New Cast Aluminum Alloys for High Performance Cylinder Heads

Cast aluminum alloys have been increasingly used in internal combustion engine cylinder head applications because of their lightweight and high thermal conductivity. Increasing demand for fuel economy and high power density has posed a significant challenge on existing cast aluminum alloys for high temperature performance. This paper reports a study of evaluating two new high temperature cast aluminum alloys Al-Q (AlSiCuMg) and ACMZ (AlCuMnZr) using semi-permanent mold (SPM) cast cylinder heads. While the new cast aluminum alloys, especially the ACMZ alloy, show a significant improvement in high temperature tensile properties, they exhibit similar fatigue performance as the commonly used cylinder head aluminum alloy A356+0.5%Cu. This is due to the presence of casting defects which is limited by existing casting processes for cylinder heads.