Aluminum heads and spark plugs

Moparmonster said

My understanding is, and correct me if I'm wrong, that aluminum's non-ferrous nature means that it naturally lowers compression when used as a cylinder head. Thus, the valves are closer to the pistons to make up for that loss, and to maintain the same compression ratio. Something like that, as I recall.

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only the chamber 'size' can affect the compression ratio, not the material it's made from.
it's not like the chamber if made from aluminum swells up when the mixture's compressed is it? :poke::lol:
it seems to be accepted that aluminum heads will work with a higher compression ratio without detonation if that's what you meant? something to do with that material transferring heat better than iron from memory?
neil.