A clean sheet engine has been designed, built and is currently being tested at Tour Engine, Inc.’s new test facility in San Diego. Based on detailed system simulations (GT-Power), first performed by Tour Engine, Inc. and independently confirmed by Wisconsin Engine Research Consultants (WERC, which are a subrecipient of this project), the engine in this project has been designed with an expansion ratio of nearly two times the compression ratio and each cylinder has been fitted with a dedicated cooling circuit to characterize and subsequently minimize the heat losses of the engine. The combination of these two features provides the theoretical basis for significant efficiency gains of the Tour split-cycle over conventional engines.