In this book, availability (Exergy) based SI engine model optimisation (ABSIEMO) is studied and evaluated. A four-stroke bi-fuel spark ignition (SI) engine model is developed for optimising engine performance based upon an availability analysis. An artificial neural network (ANN) is modelled based on availability based SI engine model (ABSIEM) results as an emulator to speed up executing of the optimisation processes programme. In this optimisation programme, constrained particle swarm optimisation (CPSO) is applied to identify parameters based upon availability and energy analysis. Moreover, in the optimisation process, the engine exhaust gases standard emission has been considered. Finally, the results of optimisation programme are compared and discussed.