Everyone keeps telling me, when i go to have my car dyno'd, that iorn gt40's HATE boost......Can anyone tell me why, and what is better about aluminum heads, and why all the shops keep saying that anything over 10psi is bad news with my heads?
alum does a better job of dissapating heat, therefore reducing the chances of detonation.
however this can be overcome by a competent tuner.
if 2 heads having the exact same flow characteristics are on the same identical engine with 1 being alum the other being cast iron. the alum head has the potential to make more reliable power--note i did not say more power.
i had a thread about this on turbomustangs a while back. I guy replied who had the same heads as me. He went 8's with over 20 psi on the same iron gt 40's. works for me
i'm with this guy.... gt-40s have a thin deck which may allow them to flex a little under head and lots of pressure...
but i guess if you have an amazing tune, you shouldnt have issues
Iron is about 2 1/2 times stiffer than aluminum, so to get the same stiffness in the deck, you need to make it thicker. Hence aftermarket heads have a thicker deck since they are all aluminum. It probably evens itself out. If there was a way to test it, I'd put money on it.