Aluminum heads

Here's a decent lecture I found on heat transfer:
http://web.mit.edu/2.61/www/Lecture notes/Lec. 18 Heat transf.pdf

Without the accompanying notes, it's incomplete. However, there are useful bits there. In-chamber temperature is lower on an aluminum head (slide 22, page 11). This makes sense. But the amount of energy removed won't be any greater with the aluminum head. The greater conductivity and lower resistance means that for the same energy 'wicked' away, the resultant temperature of the chamber walls will end up being lower.

The lecture also points out that convection is the main means by which heat is conducted, and that until ignition happens, there's little convection going on and so little heat transfer.

One of the slides also lists the exhaust valve and the spark plug as the hottest items in the chamber - which would suggest that proper mixture and spark plug selection matter more when it comes to pre-ignition than cylinder head material.