This book was written to be used as an applied thermoscience textbook in a onesemester, college-level, undergraduate engineering course on internal combustion engines. It provides the material needed for a basic understanding of the operation of internal combustion engines. Students are assumed to have knowledge of fundamental thermodynamics, heat transfer, and fluid mechanics as a prerequisite to get maximum benefit from the text. This book can also be used for self-study and/or as a reference book in the field of engines. Contents include the fundamentals of most types of internal combustion engines, with a major emphasis on reciprocating engines. Both spark ignition and compression ignition engines are covered, as are those operating on four-stroke and two-stroke cycles, and ranging in size from small model airplane engines to the largest stationary engines. Rocket engines and jet engines are not included. Because of the large number of engines that are used in automobiles and other vehicles, a major emphasis isplaced on these.