Combustion Chamber
The space inside the cylinder head and engine block where the air-fuel mixture is compressed and ignited.
The combustion chamber is the sealed space inside an internal combustion engine where fuel is burned to produce rotational force. It is formed by the top of the piston, the cylinder walls of the engine block, and the underside of the cylinder head. The shape of this chamber is highly engineered to promote turbulence and rapid, complete combustion of the air-fuel mixture.
Inside the chamber, the intake valves open to draw in air and fuel, which are compressed by the piston as it moves upward. The spark plug (or high heat of compression in diesels) then ignites the mixture, creating a high-pressure expansion that drives the piston downward, rotating the crankshaft.
Carbon deposits can build up inside the combustion chamber over time, especially in direct-injection engines. These deposits can create hot spots that ignite fuel prematurely (a condition known as pre-ignition or engine knock), leading to rough running and potential engine damage. Mechanics use chemical top-engine cleaners to dissolve these deposits and restore chamber volume.