I had a thought this morning: Aluminum has a very high thermal conductivity. AlO2 has only about 1/10 the thermal conductivity. Aluminum parts generally all have a surface oxide layer as it forms immediately with exposure to air.

What this got me wondering is, has anyone tried a coating/plating on the rotor housing coolant passages to replace the oxide layer with a more conductive material (copper,silver, etc) to increase heat transfer to the coolant? Potentially this could provide a significant increase in cooling capacity at the hot spot by the plugs, either enhancing, or possibly eliminating the need for, the surface area increases that many people are experimenting with.

Thoughts on this?