down sides to aluminum heads?

[miller]

quick question regarding aluminum heads for 440s, are there any down sides to using aluminum heads... or are they superior to stock heads in every way (performance, durability etc)

[skip68]

PRICE!!!    

[Rolling_Thunder]

some people believe aluminum heads on an iron block leads to potential head gasket sealing issues...    my experience is once the engine had been heat cycled a couple times and you re-torque the heads they are usually good to go. 

[chargerbr549]

As stated before price of the heads and usually you should run a very good head gasket(read more money) because the deck surfaces of aluminum heads are softer and can brinell very easily, follow the recommendations of the gasket manufacturer. If a person torques all the bolts like they are MR Armstrong the bolt holes won't take the abuse like cast iron heads, with all things being equal between cast iron and aluminum you have to run about one point higher in compression ratio on the aluminum head to equal the cast iron head.

The advantages is way lighter weight and repairability from cracks or from pisons and parts destroying chambers when an engine gives up the ghost, they already have hardened seats and replacable guides installed and they don't rust.


Kevin

[beedees]

Aluminum is better...hands down, especialy if you happen to drop one on your foot. (DAMHIK) 

[daytonalo]

Hemi alum heads are cheaper than cast iron

[375instroke]

As for price, 440Source is releasing aluminum heads for $699 a set this month.

[miller]

well what about cooling... i know that iron and aluminum expand at different rates so would i have to Marjory upgrade the cooling system to make sure i don't warp the heads?


my uncle told me that if i switched to aluminum heads i would have nothing but problems... i don't know if that was just back in his time or if i should still be wary

[694spdRT]

well what about cooling... i know that iron and aluminum expand at different rates so would i have to Marjory upgrade the cooling system to make sure i don't warp the heads?


my uncle told me that if i switched to aluminum heads i would have nothing but problems... i don't know if that was just back in his time or if i should still be wary

He probably drove too many of the old 2.2 or 2.5 4cyls with aluminum heads. 

[suntech]

you have to run about one point higher in compression ratio on the aluminum head to equal the cast iron head.

?

You mean CAN, dont you??
The aluminum heads can deal with higher compression ratio, with the same other criterias, over the cast iron heads. No need to compensate for anything.

[doctorpimp]

Edelbrock aren't much more expensive if you take into consideration the oversized valves and hardened seats.

[miller]

As for price, 440Source is releasing aluminum heads for $699 a set this month.

isn't that for the set that has no internals in it?.... isn't it 899 with all the guts in it, or did they lower the price?


also is there a better way to go then the internals that they are offering?

[NMike]

you have to run about one point higher in compression ratio on the aluminum head to equal the cast iron head.

?

You mean CAN, dont you??
The aluminum heads can deal with higher compression ratio, with the same other criterias, over the cast iron heads. No need to compensate for anything.

aluminum heads transfer heat faster to the coolant. aluminum also cools off faster.

when the piston goes up to the top of the compression stroke, some of the heat created by the pressurizing of the air/fuel mixture is absorbed by the engine. when you put on aluminum heads, more hear is absorbed by the heads compared to steel. this drops the cylinder pressure slightly. to regain some of the power LOST in switching the heads, upping the compression fixes that. hence why you want more compression than with steel heads.

[BrianShaughnessy]

  I borrowed this part of an FAQ from maundmotorworks.com .  It's rather simplistic but whatever - it gets a few points across... there are more to be made beyond this. 

  Frankly I believe most iron heads are obsolete.   A lot of other people must agree with me as this is reflected in the going rates for iron heads on ebay and the classifieds also. 

  Rather than build a 12.5 to 1 engine that you can't run pump gas in,  I'd rather have a 10 / 10.5 to 1 aluminum headed engine that I can put 93 in and drive 3000 miles a year.   To do the same with iron heads you'd have to build a 9 / 9.5 engine.   

  We don't have 100 octane gas readily available like there was in the 60's or even the Sunoco 260 / 96 in the late 70's to run.   If you have some alternate source of readily available semi affordable high octane fuel - consider yourself lucky and have a party!     NOTE:   If you're building a race car and are going to run 110 from a 55 gallon drum ....  this isnt' about you.

Q4. What is the advantage to spending all that money to go to aluminum heads?
A: There are many advantages to using aluminum heads.
The first is weight. Aluminum heads are considerably lighter than their cast iron ancestors. The second advantage is construction. Unlike the aluminum heads of the 1960s that were expensive and troublesome, modern aluminum heads are made with modern computerized casting systems and CNC machining technology that was simply unheard of 40 years ago. Combine those technologies with the advances in metallurgy that have come about since then, and the case is clear that aluminum heads are superior in construction. Another reason is performance. Most aluminum heads on the market feature bigger valves and ports than their iron ancestors. In basic form, the aluminum heads usually outperform their cast iron counterparts. Even with ported cast iron heads, the aluminum heads usually are tough competition. And the final advantage is price. Original head castings are getting more and more expensive all the time. So consider what it takes to put together a performance set of big block Mopar iron heads. First, a viable set of heads to use are not cheap. Then consider the cost of machining and all the new parts such as bigger valves and springs. And don't forget about those hardened seats if you have older heads. Then factor in the cost of a good port job. A good port job can cost upwards of $800+. And all this is being done to a set of heavy, 35+ year old castings made with 35+ year old technology. With aluminum heads, they are lighter, perform better, and you have spent the same money (sometimes less) for new stuff.

Q5. Doesn't aluminum crack when it gets too hot?
A: Any vehicle requires a good cooling system.
Without this, any head will fail from heat whether it is aluminum or cast iron. Another nice thing about aluminum is that it is 100% repairable. Imagine that set of iron heads in answer 4 that had all that work and money tied up in them. What happens if they cracked? Chances are they would get thrown in the scrap pile because cast iron is difficult and expensive to weld if you can even find someone good enough nowadays to even do it. And if those heads are doomed to the scrap pile, then the process and expenses start all over again. If you crack aluminum, it can be easily welded up and remachined for considerably less money. It's almost like a one time investment.

 

[Jon Smith]

http://www.carcraft.com/techarticles/ccrp_0602_iron_versus_aluminum_cylinder_heads_test/index.html

[suntech]

The article linked above kinda kills the theory that you NEED more comression, to compensate.
That some are going higher on aluminum heads, compared to an iron head combo, and gets away with it, kinda tells me that you CAN go a little higher, with the aluminum heads.
I think the biggest gain though, is the weight savings!!!!!
In the article above they saved 61 pounds, just with the heads, on a small block chevy. What is it then on a BB/ Hemi ? maybe 80?
Then, with another rougly 150 pounds (WP hemi 308 iron, 142 aluminum) saved by going with an aluminum block, then we´re talking about A LOT!!!!
Imagine loosing 220-240 pounds in the nose/ total weight!!!! That compensates for a lot of HP, and helps car- balance a lot.
Would rather spend money on a mild engine combo, that saves weight, over a wild one, to compensate for all the pounds in the nose.

[Steve P.]

I look at it the same way. A car on a diet means a quicker car all around.

There is even more weight that can go away with changing K-members and steering boxes. Wheels, tires, fenders, hoods, radiators, bumpers, intake/exhaust manifolds, water pump and housing,  etc. etc....   

I'll bet you could take 5-600 pounds out of a race car easy. Then you end up adding a little with a roll bar and frame ties and that heavy aZZ Dana.

Drop your 10 second Hemi in a 68' Imperial and see how much time it take to get down a 1/4 mile track.. Hahaha... Weight is time.... The more you have, the more it takes..

[375instroke]

As for price, 440Source is releasing aluminum heads for $699 a set this month.

isn't that for the set that has no internals in it?.... isn't it 899 with all the guts in it, or did they lower the price?


also is there a better way to go then the internals that they are offering?

It's wasted money if you need to change the springs due to cam requirements, and maybe you want different valves and keepers.  Even at $899, isn't that cheap for closed chamber heads that flow 300 or so CFM?  How much would a set of 915 heads with guides, decking, seats, valves, and port job cost?