15-08-2023, 05:40 PM
The technical term is copperised. Not sure of the exact process but it’s supposed to be more durable than straightforward plating. The idea was to make the surface inside the cylinder more heat conductive to prevent local hotspots forming and so delaying pre-ignition. It wouldn’t make a deal of difference to overall heat transfer and cooling and I’m not sure if it helped much other than make you happy you had done something. Incidentally, don’t Google copperising. It seems to have a different meaning these days.
Alan Fairless