Editing Diesel engine (section)

=== Noise ("diesel clatter") ===
[[File:AKD 112 Z.webm|thumb|Engine noise of a 1950s [[MWM AKD 112 Z]] two-cylinder diesel engine at idle]]
The distinctive noise of a diesel engine, particularly at idling speeds, is sometimes called "diesel clatter". This noise is largely caused by the sudden ignition of the diesel fuel when injected into the combustion chamber, which causes a pressure wave that sounds like knocking.

Engine designers can reduce diesel clatter through: indirect injection; pilot or pre-injection;<ref name="Böge_2017_1150" /> injection timing; injection rate; compression ratio; turbo boost; and [[exhaust gas recirculation]] (EGR).<ref name="EngTips" /> Common rail diesel injection systems permit multiple injection events as an aid to noise reduction. Through measures such as these, diesel clatter noise is greatly reduced in modern engines. Diesel fuels with a higher [[Cetane number|cetane rating]] are more likely to ignite and hence reduce diesel clatter.<ref name="Comb in IC" />