Ok i kind of know the question to this post I know that aluminium is better, But how much?

I might get 6.0 but it is coming with cast iron heads. From what I know the 6.0 cast iron are identical to the 6.0 (317) aluminium heads. Here is the list that I provided with cons and pros.

Aluminuim (Pros): able to dissipate heat better which would allow to run a little more compression if wanted. The mixture of air and gas is slightly cooler due to aluminium.

Aluminium (Cons): Under sudden Engine over heat the heads are considered crap .

Cast Iron (pros): pretty freakin durable. Will still be good if overheated (I know this won't happen though)

Cast Iron (cons): Might get more Knock retard due to everything being hotter (I am kinda of assuming this one.)

Do you think spending another $400 or whatever on some aluminum ones is worth it. How much more power can I gain since everything is identical? I know that under high compression motors 11 and 12:1:1 it is better to run aluminium but I will never go that high on compression.

 

I thought that the crank was longer on the blocks that had the iron heads and you couldn't use it or something like that? Everything I've read says look for aluminum heads with "317" castings....(or 371?)

 

I would get aluminum. Overheating is something to plan for, but not very probable of happening. You could go higher comp. but you say youre not doing that. I think the biggest gains are the ability to disapate heat better and weight savings. All things equal, I've also heard they flow better?

 

are you saying that the aluminium flow better?

 

Don't sweat the crank being longer, because you're getting the tranny that goes with it. Aluminum offers a little weight savings, and from my die grinder experiences its a lot easier to port.

I'd love to know for sure on the flow #'s. I beleive they have the same sized runners and valves, so who knows for sure?

 

That is what i want to know also if they do flow better. I have in some of my notes that the sand cast heads flow better but which are they. Are they the aluminium or the cast iron?

I have: 706 cast heads flow better. But dont know which one is which.

 

Yeah the crank is longer but towards the tranny area, which would not effect anything with the heads.

 

I have heard that aluminum heads flow better. I can't find anything to back it up, but I think it has to do with the runners being smoother? I do know they are easier to port/polish, but I think they have less casting imperfections. Maybe thats why they flow better. Or maybe I'm just crazy?

 

Get aluminum. You never know when you might go to a high com setup.

 

Get the aluminum ones you will probably be like everyone else they say are going to be happy with a setup then they want more so why not go ahead and get a base that you can work with.