PREIGNITION, Mr. Heron points out, is an old, if not well-known, disease of Otto-cycle engines.
Despite its long history, however, there is much confusion in the terms used to describe it and the other forms of uncontrolled combustion in spark-ignition engines.
The author has tried to bring some order out of the confusion by defining the three terms: knock, preignition, and autoignition.
He also relates his experiences with destructive, runaway preignition in aircraft engines during World War I.
THIS paper and the four that follow, by Melby-Diggs-Sturgis, Hirschler-McCullough-Hall, Williams-Landis, and Winch, constitute the complete Symposium on Preignition that was presented at the 1953 SAE Summer Meeting. Discussion of all papers is published at the end of the last paper in the group, by Winch.