Several other split-cycle engines (Scuderi engine and Zajac engine, for example) have been proposed in the past but none have been successful due to detrimental compromises in the thermodynamic cycle (over-compression, charge storage, heat loss and retarded combustion) and the reliance on ultra-fast valves that pose reliability challenges. The Tour engine is the first split-cycle engine to closely emulate the thermodynamic cycle of the 4-stroke engine (integrated cycle) and offers a comprehensive set of solutions.