yes i know what the ron number means
and ok your right, it probably doesnt actually burn hotter, but, it does burn longer, (well slower) which in turn can mean it still burning as it leaves the cyl. and i've burnt exhaust valve's on car b4 from running avgas which ran fine b4 it was on avgas, but that engine was piss weak compared to any thing merc ever built.
and as far as cars not using sodium valve's anymore
one of the best 6's ever built (along with the m103/4
). the rb26, and nissan v8, the vh41/45 uses them aswell