I posted this in the truck section. I am trying to find out how much better are aluminium heads., than cast iron. I am wanting to get 6.0 317 casting heads. the specs from cast iron to aluminium are the same. What is you take thanks for the any input.

https://ls1tech.com/forums/showthread.php?t=330438

 

They are basicially the same, just different material used.
If you are just using them stock on a truck you will be fine.
If you are porting them, using them on a boosted setup or doing pretty much anything other then stock go aluminum.

 

aluminum allows for better cooling and higher compression ratios. just switching to alum heads prob wont gain you too much power unless you go with a set of 5.3 heads to raise the compression a bit. expect a 3-4% power increase for every full point of compresssion increase (i.e. 10.1:1 to 11.1:1). theres really no point in doing the swap if youre gonna put the same 6L heads back on...

 

all being equal Iron heads will make more power then aluminum heads..


same octane
same compression
same timing

but the disadvantages to iron heads are.. cant run as much timing, cant run as much compression, harder to port and are 50lbs heavier..

the advantages of aluminum heads would be.. 50lbs lighter, dissapate heat better (sp?), run more timing, run more compression, easier to port.

 

how the hell do you figure that?

its 2005 people, i cant see any good reason to use cast iron heads for anything other than keeping the boat from drifting around the lake.

 

o man tu funny

 

that is a fact, Iron heads can make power..


that was a very ignorant statement

 

The old iron 6.0L heads have ports that are modeled after the old LS1 ports. The 317 aluminum 6.0L heads have ports modeled after the LS6 head and therefore flow quite a bit better than the iron heads. That's the biggest reason to choose the aluminum heads. They're better to start off with.

 

I'm not talking about 2 specific heads against each other..


I'm talking about in general Aluminum Vs Iron.

 

While that may be true, the original question was whether specific iron heads would make more or less power than specific aluminum heads. If you don't plan on porting either and the compression is the same, the aluminum heads will be 10-15 hp better than the iron heads (mostly from the better flow). If the flow and combustion chamber were the same, the iron heads would probably have a 5 rwhp advantage due to their better heat retention. But the aluminum heads have a 15-20 rwhp advantage from a flow standpoint, giving them a net 10-15 rwhp advantage. If that's worth $400 to you, then I say go for it!

 

I see I always had the impression that both cast iron and the aluminuim heads were exact replicas of each other. I did not know that the flow charecteristics were different. I am thinking for sure aluminium now. I am also thinking about maybe adding a little more compression.

 

LOL here. You are right on with that at least for non-diesel!

You need to go back to why GM Powertrain used any iron heads at all in the truck version of the LSx engine.

As I understand it, the Powertrain folks wanted to use aluminum, but the "truck folks" said no because they thought iron would give better engine durability over the long haul in trucks. Powertrain had to convince them that not only were the aluminum heads as good as the iron for durability, they were better. That took some time, so some early truck LS engines had iron heads. Anyway, that's the story I got from a "Deep Throat" inside the Company.

You can decide for yourself, but the aluminum heads made a better running, better heat rejecting engine which slightly improved fuel economy due to less weight and how engine temps could be manipulated. All of this also helped durability. Didn't hurt power output and acceleration either.

Sometimes the wheels (pun intended) at large OEMs grind exceedingly slowly.

 

I've seen tests on the same design heads from world products and the aluminum heads made more power. I would think Iron would hold heat in better and make more power. I didn't understand the results, but I would go with aluminum. Aluminum is infinitely repairable, disapates heat for more compression, lighter. No contest.