Dodge Durango Forum II

G. Matsushige Inst. Spec.Kamuela Hawaii
grant@cfht.hawaii.edu

Here's some general information on Al heads. Generally they can make more power. Notice the work generally.

Here's why. Typically, when it comes to an engine, you want a moderate amount of heat in the combustion chamber. You need just enough to keep the plug from fouling but not too much because it can cause knocking. Al is much better at transfering heat to the coolant then steel. So for combustion chambers, Al tends to be a better suited material. It's not all a free lunch however...

You want as much heat (reasonable amount) in the cylinder walls. It does reduce friction of the pistion sliding up down the cylinder. However, too much isn't good either because the oil will burn up.

So if an engine could get the coolant to flow through the heads first and then through the block it'd be better. The new small block chevys in the vette, camaros and firebirds do this. A guy named Smokey Yunick did this trick way back in the mid 60's and was banned from racing in nascar because he was said to have an unfair advantage.

So here's part of the problem. Aluminum and cast iron expand at different rates as they heat up. So extra care must be taken when maintaining or taking care of these types of engines.

These are just generalities and as often there are exceptions.

aloha,
g

[ This message was edited on Fri Aug 1 at 1:24am by the author ]