High Quality Content by WIKIPEDIA articles! A motorjet is a rudimentary type of jet engine which is sometimes referred to as thermojet, a term now commonly used to describe a particular and completely unrelated pulsejet design. At the heart the motorjet is always an ordinary piston engine, but instead of driving a propeller, it drives a compressor. The compressed air is channeled into a combustion chamber, where fuel is injected and ignited. The high temperatures generated by the combustion cause the gases in the chamber to expand and escape at high pressure from the exhaust, creating a thermal reactive force that drives the engine.