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Old 03-16-2009, 01:07 PM
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alumninum VS steel heads

right now im debating between alumninum or steel heads(781s)

from whatIi can see the alumninum will be lighter,flow better and allow me to run lower octane then what I would woith stell.Is there another other pros and cons between the two?....as of right now the price will be the same let me kow what you think.

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Old 03-16-2009, 01:28 PM
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You've pointed out all the benefits that I know of, plus if you damage them, aluminum can be welded easier.
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Old 03-16-2009, 01:55 PM
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Thanks buddy thats another one for the alumninum

Last edited by 454cutlass86; 03-16-2009 at 02:26 PM.
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Old 03-17-2009, 12:54 PM
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There are also bragging rights when you open the hood.....
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Old 03-18-2009, 11:12 PM
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aluminum is MUCH more sensitive to Thermal Shock. If the engine is HOT and you pour cold water in the radiator, there is the possibility of cracking the heads.. or spraying a hot engine with water (even just mud puddles) could get ugly.

Threaded holes in Aluminum strip MUCH more easily..(spark plugs for example) Use of anti-sieze is mandatory.

Spark plugs can not be changed when the heads are even warm with aluminum... not so much a big deal.. but can be an annoyance having to wait for the engine to be 'cold' to change them.

Using aluminum heads on an iron block can create headaches too, since the two metals expand at different rates.. There is a certain type of head gasket that helps eliminate this. I just can't remember which one.

and IIRC, aluminum heads warp a lot easier, especially if you accidently overheat the engine..
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Old 03-19-2009, 09:52 AM
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Quote:
Originally Posted by 454cutlass86
right now im debating between alumninum or steel heads(781s)

from whatIi can see the alumninum will be lighter,flow better and allow me to run lower octane then what I would woith stell.Is there another other pros and cons between the two?....as of right now the price will be the same let me kow what you think.
Aluminum doesn't flow better. The same head cast in iron or aluminum will flow the same. There are some great flowing iron heads and some terribly flowing aluminum heads.

Octane tolerance is a little better with aluminum, but as far as power production, the same head cast in aluminum and iron, they will both make the same power. Iron heads have the potential to reflect more heat back into combustion (which is why they tend to detonate easier) but that also means more of the heat from combustion is applying pressure to the piston. Iron sometimes makes more power than aluminum on otherwise identical head castings.

But, its not a really measurable difference most of the time. But, consider aluminum heads strictly a benefit for their 1-2 fewer octane points, and their weight reduction.
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