The aim of this paper is to compare two simulation software platforms, AVL BOOST™ and Ricardo WAVE™ as used to simulate HCCI and SI GDI engines with the intention of maximising the engine’s efficiency and minimising the emissions. This paper compares these platforms in an experimentally validated model to analyse a spark ignition and a Homogeneous Compression Ignition Charge (HCCI) single cylinder 4 valve gasoline engines with multiple configurations and running parameters in order to find the most optimal set-up for the engine, with the prospect of allowing an optimum engine to be built and tested in real world conditions without the need for multiple expensive prototypes and long delays.