Depending on the vehicle’s driving mode, the combustion process in spark ignition engines may be disrupted. Violation of the combustion process can be called detonation (spontaneous ignition). Detonation entails specific characteristic sounds and leads to a decrease in engine power and its efficiency.
Detonation in the engine leads to high temperatures and pressure bursts that have a mechanical and temperature effect on the engine parts: cylinder head, gaskets, pistons, sliding bearings. Violation of the combustion process leads to burnout and scuffing of the pistons, damage to the valves, and ultimately to the destruction of the engine.
How does detonation occur in an engine?
During the sparking of the spark plugs, the combustible mixture ignites, with the piston almost at top dead center. Complete combustion of the combustible mixture occurs after the piston passes through the TDC. From the spark plug comes the front of the flame. During the rise of the piston, the pressure rises and during the combustion of the combustible mixture, an increase in temperature and pressure is formed. The temperature of the mixture reaches high values and in some places self-ignition occurs. Additional flame fronts appear that act on the walls of the cylinders, which is accompanied by peculiar metal knocks.
Why does detonation occur?
Various factors can influence detonation processes, such as: early ignition timing, high charge density, fuel quality, fuel octane, high compression ratio, carbon deposits in the combustion chamber, insufficient cooling, improper design (geometry) of the combustion chamber.