Focusing on thermodynamic analysis--from the requisite first law to more sophisticated applications--and engine design, here is a modern introduction to internal combustion engines and their mechanics. It covers the many types of internal combustion engines, including spark ignition, compression ignition, and stratified charge engines, and examines processes, keeping equations of state simple by assuming constant specific heats. Equations are limited to heat engines and later applied to combustion engines. Topics include realistic equations of state, stoichiometry, predictions of chemical equilibrium, engine performance criteria, and friction, which is discussed in terms of the hydrodynamic theory of lubrication and experimental methods such as dimensional analysis.