Only thing I can think of is weight reduction. Am I missing something?

 

removes heat from the engine better allowing for increase in compression with out increase in octane compared to an iron head engine

 

IIRC along with ede's post they also allow for more timing advance without the ping.

 

Still, under ideal conditions, cast iron heads that are identical in every way to aluminum heads will produce more hp.

Why?

Because they retain the combustion heat better than aluminum.

 

The heads also tend to be designed better, with bigger and better shaped intake and exhaust runners.

You generally find newer design technology in the combustion chambers than is available with iron heads, Vortec heads being an exception as well as some other aftermarket pieces (Pro Action?)

 

Vortec iron!!!!!!!!:rockon:
And they are cheap!!!!!!!!

 

Yes all things being equal the iron will always make more power. The true advantage to aluminum is their weight reduction, creating a better front rear weight bias.

 

not to mention, alum heads are easier for the aftermarket to make then iron heads...

so for the longest time, the better aftermarket heads were alum.. after awhile for performance, people believe alum is the only way to go.

 

do they make vortec heads that are smog legal? in california?

 

Ok, so from this information, basically what I understand is its not so much the material but the aftermarket aluminum heads are just designed better. So speaking theoretically, if their were a pair of heads, one alum, one iron, both exactly the same. The iron would be the better choice because it retains the heat from combustion? Or is the weight reduction worth it?

 

I'm not sure how much weight would be reduced, but just aluminum heads wouldn't make that much difference. It's the combination of all the parts on (or hacked off) the car that will make the difference.

it's just like engine mods. just a free flow muffler won't give you a world of power gain, but in combination with other mods (both great and small) you'll have a huge gain.

 

now you're running into arguing, theory ground.



on one hand, theres a large group of people that believe that the detonation resistance of the alum lets them run a lil more cyl pressure, and a lil more power.

on the other hand, theres a large group of people that believe that the heat retention of the iron heads makes the motor more efficent, and makes a lil more power.

and on the 3rd side, some people say the alum weight advantage of the identical alum and iron heads put the alums out in front.



but really, its up for grabs...... people will argue their points til their blue in the face, but when it comes down to it, theres not too much of a diff between them if you take advantage of their pluses and minimize the minuses.

so if you're running alums, you might as well up the compression a lil...


personally, im buying Alum heads for the weight loss, and the detonation resistance... that way, i can get away with a bad tank of gas if im out in the middle of nowhere... a kind of insurance for my car since i like road trips

 

Aluminum is also easier to port and repair.

 

what people have to figure out is

does the fact aluminum allows more timing and compression;

make more power than the fact iron heads hold in more heat.


which of the above do you think would help out power more?

I beleive its aluminum, compression and timing always seem to help more than a little extra heat. if i want it hotter ill turn on the fans later... sheesh.

 

not the same effect.



but anyhoo i agree.... i merly stated both sides of the argument so that he would know.

 

The weight difference between my stock iron heads and my aluminum ones was something like 40-50 pounds.

 

40-50 pounds

i just took the iron heads off of my engine and they didnt seem like they weighed that much. i had no problem moving them around, picking them up, etc. both of them only feel like they weigh 50 pounds together.

 

I just weighed my Vette alum. heads and my Iron ones. Iron ones weighed 45lbs more. That is bare heads. 45lbs is a .05 in the quarter mile by theory. Also alum. is better for performance, you can run more compression,timing and not have to use high octane gas.

 

nonsense iron heads weigh about 65 Lbs each for small block chevys.