Ok so this is probably an unneccasary and dumb idea, but what if you take an opposed piston engine, and electrically isolate the pistons. Then instead of run the spark through a plug, make it jump between the two cylinders. I feel like it would create an electrical storm inside the cylinder igniting more fuel then a spark plug could, with a possibility for very low clearence and thus high compression. For those of you who dont know what an opoc engine is here is a picture. .