I spent a couple months digging through German history books to find the details.
Understanding machine translation of German can be a puzzle but I got through it.
This article goes back to the time and the people who started the whole thing.
It is an account of the invention of the 4-stroke internal combustion engine.
It changed the world.
One of the important and to some people mysterious systems is the ignition.
This article starts with auto ignition early history and ends with the GM HEI.
All the details about the GM HEI system plus information about modifying it for high performance use.