PRECOMBUSTION REACTION IN THE SPARK-IGNITION ENGINE 500191
IT has been found by the authors that fuels fed to a crbureted spark-ignition engine may undergo severe “prereactions” during the compression stroke prior to spark ignition as differentiated from “preflame” reactions which take place ahead of the advancing flame front in the remaining unburned part of the air/fuel mixture in the cylinder after ignition.
It appears that the extent of prereactions is a function of fuel type and engine operating variables. The alteration or prereaction of fuels increases with severity of engine operation. Intake temperature and compression ratio are major variables affecting engine severity.
These tests show that the prereactions play an important part in the knocking phenomenon.