Quote continuation. Ionization current?? Saab did this. GM did this. Probably others. But Smokey was doing it in the 50s. I wonder if there's an SAE white paper on this. Something tells me he wasn't the kind of guy to author (or co-author) an SAE white paper. Which is a real shame.
Although the original hot-vapor engines relied on a carb with no computer, modern 21st century fuel injection and computer enhancements could be used to fail-safe the engine in event of system malfunction. For example, present engine management systems still rely on an oxygen sensor and a knock sensor to provide feedback to correct the air/fuel ratio and timing, respectively, but this a catch-up game, subject to a potentially deadly time lag on an engine always operating close to the limit. It is theoretically possible to put an inductive pickup on a spark plug wire that can be used by the computer to measure the ionization gap across the spark plug in real time. A change in the ionization gap indicating a problem in the cylinder would manifest itself as a slight change in electrical current read in milliamps. "If there's going to be a failure from temperature or heat, you'll know it instantaneously," Ralph says. "I worked on the genesis of this at Ethyl Corp. [using analog milliamp meters] all the way back in the '50s when I was still a student. With real-time feedback, the computer could then change the spark, the fuel ratio, and someday the compression ratio or the displacement to compensate before catastrophic failure occurs."
I built a 2.2 liter HVC that essentially required way different cam, taller gearing, a lot more manifold heat with less volume and other stuff. I wound up with a modified IHI, an expensive pile of aluminum and a set of wheels that hauled ass like a wildcat after a tabasco enema all while knocking down 40mpg in a dodge minivan.