internal-combustion engine, one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power. Such engines are classified as reciprocating or rotary, spark ignition or compression ignition, and two-stroke or four-stroke; the most familiar combination, used from automobiles to lawn mowers, is the reciprocating, spark-ignited, four-stroke gasoline engine. Other types of internal-combustion engines include the reaction engine (see jet propulsion, rocket), and the gas turbine. Engines are rated by their maximum horsepower, which is usually reached a little below the speed at which undue mechanical stresses are developed. Sections in this article: Introduction Engine cycles SI and CI engine Two stroke engine Fuels and lubricants Combustion Adiabatic engine Bibliography

I have completed my M.E, PhD in Mechanical Engineering from Anna University, GCU, and the field of research is Internal combustion (IC) engines. At present I am working as Professor in Higher College of Technology, Muscat, Sultanate of Oman. I have more than twelve years of experience in the field of Teaching profession.