Understanding Automobile Engines

Automotive engines have transformed over the years, but two main gasoline powered combustion engine designs remain: the 2-stroke and the 4-stroke.

Internal combustion engines are engines (or motors) in which the fuel is burnt inside the engine itself, as compared with external combustion engines like the steam engine where the fuel is burnt outside the working cylinder of the engine. The petrol engine and the diesel engine as used in modern automobiles are both internal combustion engines. The chemical energy of the fuel is converted into heat energy by combustion, and part of this heat energy is converted into mechanical energy by the engine.

During an engine’s combustion cycle, the piston moves up and down within the cylinder. The terms “top dead center” (TDC) and “bottom dead center” (BDC) refer to the piston’s position within the cylinder. TDC is its position nearest to the valves, and BDC is its position furthest from them. A stroke is when the piston moves from TDC to BDC, or vice versa. A combustion revolution or combustion cycle is the complete process of gas and air being sucked into the piston, igniting it, and expelling the exhaust.