Pre-ignition Pre-ignition Pre-ignition (or preignition) in a spark-ignition engine is a technically different phenomenon from engine knocking, and describes the event wherein the air/fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events. The phenomenon is also referred to as 'after-run', or 'run-on' or sometimes dieseling, when it causes the engine to carry on running after
Archaic smile Archaic smile The Archaic smile was used by Greek Archaic sculptors, especially in the second quarter of the 6th century BCE, possibly to suggest that their subject was alive, and infused with a sense of well-being. One of the most famous examples of the Archaic Smile is the Kroisos Kouros. The dying warrior from the west pediment of the Temple of Aphaia, Aegina, Greece is an interesting context as the warrior is near death. In the Archaic Period of ancient Greece (roughly 600 BCE to 480 BCE), the art that proliferated contained images of people who had the archaic smile.