I recall growing cast iron pistons to get additional life out of the old lapped iron engines. But that was in a kitchen oven turned to broil for a considerable amount of time. I doubt the rings in our engines are getting hot enough to do this. Maybe the first thousandths of an inch or so. Also cast iron growth is cause by the carbon nodules and perhaps other crystals in the metal expanding. Steel and aluminum do not have carbon nodules, though the high silicone aluminum does have silicone nodules. Still I don't think our engines benifit from heat cycling, though it does help to break in an engine quickly (high pressure, high heat) without overheating it. Though I prefer to just let them run. After I am confident they are running well I usually find something to do at the nearby work bench, or water the garden or something.