>All else being equal, aluminum heads will make LESS power than cast iron
>because of this heat loss to the coolant. They are not as efficient. Heat
>that would otherwise be used to build torque by pushing on the piston is
>dissipated into the atmosphere by the cooling system. (Band-aid fixes include
>thermally coating the combustion chambers, or increasing compression as
>stated in other posts). The main advantages to aluminum are that it's easier
>to machine and repair than cast iron, the lighter weight can be a benefit to
>handling and in drag racing, and the fact that they usually have a better
>port design than production heads... But just slapping on a set of aluminum
>heads without making any other changes is no guarantee of increased HP.
>
>Scott
Yep. But most aluminum heads are designed for high performance. That
means they are meant to be put on real engines with real muscle that are
designed to work hard. Higher compression, ported and polished intake and
exhaust ports and runners, lots of advance and high octane fuel. That with
O-ringed head and block, and locked down with studs. All produce excellent
power if done right and with the necessary support hardware to get the
benefits. But slapping on an aluminum intake designed for high
RPMs (bigger ports) on a basically stock engine is a waste of time and
money. My opinion on why OEMs use aluminum intakes is so they can squeeze
that little bit of extra power by running a meaner advance curve without
the side affects of pinging with regular 87 octane gas.
Mike
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