Aluminium v cast iron cylinder head

[Ian Williams]

I am not sure that there is a conclusive answer, Aluminium heads are supposed to reduce maximum horse power due the the improved thermal properties conducting too much heat from the combustion chambers, however I have read reports that on dyno tests they produce more torque than cast iron heads. I stress however that the tests I have read are all on bigger OHV engines, as I see it the big advantage of alloy on our engines is that it can be cast more cost effectively so you can get a better designed combustion chamber at an affordable price. If two identical heads were cast one in alloy and another in steel then dyno tested back to back on the same A7 engine I am not sure I would wager which would be better, I have my hunch but perhaps some of our more enlightened contributors have a definitive answer.