gr8whte

i have a question, what are the advantages of having aluminum heads as opposed to cast iron??

Eddie 70

One of the biggest, obviously, is weight. They will allow you to run slightly higher compression ratio and give up their heat easier.

page62

Ironically, because they give up their heat easier, you NEED to run at higher compression in order to keep them hot enough! But that's neither an advantage nor a disadvantage if you're running the right CR.

Overall, I'd have to ask what you're trying to achieve. And please tell us what you currently have: year, engine, what's currently stock and not. You need to look at the overall picture as opposed to individual components...

vette rod

aftermarket heads allow for bigger valves,better valve angle,port location,chamber size. They weigh less and the aluminum is easier to work with when modified.

gr8whte

oh im not tryin to achieve anything, im just curious as to what the advantages are thanks again cf

Z-man

In addition to their light weight, because of their heat transfer capabilities, you can run a higher compression ratio and get more hp.

kaiserbud

Won't aluminum heads allow you to achieve running on lower grade gasoline with a tad lower compression?

EDITED - I meant to say HIGHER compression.
.

vette rod

depends on the chamber size

68/70Vette

Pick up a cast iron engine head. Then pick up the same head cast in aluminum. This little experiment will tell you why you want aluminum heads. The same goes for cast iron water pumps. Put on an aluminum pump. And the traditional starter motor. It's a big iron clunker. Get a mini torquer motor. Replace the stock steel wheels with aluminum. Just getting rid of the spare wheel and carrier hardware also deletes a lot of weight.

My 1968 Corvette Convertible had a delivered weight of 3070 pounds. (5 gallons of gasoline in the tank). I think the car will now be weighing a little over 2800 pounds with all of the aluminum substitutions, composite rear spring, and deleting the rear wheel carrier. The ZZ4, with the hotcam addition, supposedly has an honest output of 400 horsepower. 400 real horsepower and 2800 pounds of weight should make a good steet car. Now...if I can just get the thing finished and on the street!!

Ironcross

Most or all of the performance aluminum heads have the largest valves and completely machined for the most available HP. Also if it`s a BB engine, you can drop 75 lbs. off the front end immediately. The less weight your moving also helps.

79VetteMike

You can say, "I have aluminum heads."

djcwardog

If switching from CI to Al, I've read that you can add another 0.5 to your compression ratio and still avoid detonation (due to enhanced heat transfer properties)...good to know when picking pistons for a rebuild. Of course, spending the money for a set of Al heads will also get you big valves, clean chambers and ports, etc... You could do all that to CI heads as well. If I ever change heads on mine, they will be Al.

BigBlockk

In addition to all the other points aluminum can be repaired and modified by welding.

BigBlockk

Later.....

71vetteLT-1

i would be careful doing that, could easily heat up and warp it if you're not careful...if even do it at all, why would you want to anyways? if it's cracked the crack most likely goes deeper than the surface or will spread...

vette rod

You can move ports in the extreme cases to gain your maximum air flow. I have a set of heads on a 732 cid that all the ports are welded and moved and the heads are even offset on the block to get the valve away from the cylinder wall to improve air flow.. This is normal in the real racing world. as far as warping the head if done correct no problem, besides you could just deck the heads and run a thicker head gasket to keep the chamber size correct.

71vetteLT-1

guess im wrong,

redc3

the ONLY true advantage is weight savings. cast iron heads can actually deliver MORE hp because of heat retention. most guys will disagree because now their $$ aluminum heads arent so cool anymore. but its still true. but given the weight youve saved with aluminum, you might have a faster car with less hp. and what? you cant weld cast? this is news to me!

Twin_Turbo

The real advantage is not the weightsavings nor the compression, the real advantage is that the fact that you can run a point higher compression and retain a similar thermodynamic balance to an iron head gives you the ability to run a longer stick, the higher compression, even with the increased pumping loss of the longer stick, will ensure that you still have a reasonable cylinder pressure in the lower rpm region, so you can maintain a good cylinder pressure there and make more power higher up in the rpm band.

Fevre

I just like to brag about em, guess the weight I am saving is offset by the weight of my fat head.

Yellow73SB

I was going to say that. My blown up motor i ahd to ahve the head fixed.