The Engine Research Center (ERC) is a world-leading research group at the University of Wisconsin-Madison, dedicated to investigating the fundamental thermo-physical processes that control combustion performance and the pollutant emissions formed during combustion in internal combustion engines. The ERC is devoted to fundamental research on both Spark Ignited (SI) and Compression Ignited (CI) engines, including research through combined experimental studies (with optical and metal engine facilities), computational fluid dynamics (CFD) studies and optical sensing investigations. This work is supported by fundamental studies of fluid mechanics, heat transfer, combustion, sprays, emissions, laser diagnostics and after-treatment systems. Several areas in engine research have been pioneered and extensively investigated at the Center, including Reactivity Controlled Compression Ignition (RCCI) and Low Temperature Combustion (LTC) research.