Being a car mechanic since 1962 I have always been interested in all sorts of propulsion devices. When I was at tech school for my apprenticeship I designed a four stroke engine that the inlet and exhaust valves were operated by solenoids. The idea was to get rid of power wasted by the force needed to turn the camshaft that is impossible to turn by hand on a conventional engine, whether it would have used less power than the electrical power needed to work it I don't know, and of course at the time it was not possible to actually make it !. I was also involved in the last 5 years with an engine that had a variable compression ratio with pistons that had sprung loaded top crowns, although we tried really hard (and spent a lot of time on it and had it actually working) we decided that it probably wouldn't be suitable for a road going engine that would have to travel thousands of miles a year.
A good friend of mine was a mechanic on ships and I was aware at the enormous size of the huge engines after he sent me a picture of him standing on top of a diesel engines piston inside of a cylinder !
From 1968 to 2011 I was involved in competitive motorsport and had great success building my own race engines, I won approx 280 races and 2 British Championships.