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Old 01-05-2008, 02:14 PM
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Aluminum vs. Cast Heads On SBC

Is there any performance advantages of using an aluminum head vs. a cast head besides the difference in weight?

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Old 01-05-2008, 02:31 PM
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They are easier to repair ... and easier to port/polish ... also they tend to detonate less at the same compression ratio.

They weigh 25 pounds or so less EACH ... so that's almost 50 pounds TOTAL.
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Old 01-05-2008, 02:32 PM
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You can run a higher compression ratio without detonation with aluminum. Aluminum is also more common to get cnc machined ports. If im wrong, please somebody correct me.
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Old 01-05-2008, 02:44 PM
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The big benefit is weight. Years ago it was mistakenly thought that identical aluminum castings made more power, which was a misconception based on the fact that only really high performance cars had them. Later, it was theorized that the same casting in aluminum made LESS power because of its ability to wick heat away faster which lowers combustion temps.

In actuality, its pretty much a wash. If you have two identical castings; one in aluminum and one in iron, they will both produce almost identical power. Hot Rod and Car Craft have both done tests that show the power curves being almost exactly the same. But, if you are at a point where more compression will help, aluminum will let you run usually a half to full point more compression on the same octane; or you could also look at it this way... it will require more compression to maintain the same cylinder pressures.

But, unless you have specific test data that proves otherwise, consider aluminum heads a weight and porting benefit and nothing else.
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Old 01-09-2008, 07:05 AM
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What he said.

Aluminum dissipates the heat at a much faster rate than iron. The efficinecy of the internal combustion engine lies in it's ability to 'efficiently' burn the a/f mixture and transform heat energy into rotational force. When using aluminum (iron too), heat is lost into the motor, cooling system, exhaust,atmosphere etc. The idea that you can run higher compression comes after the fact that you actually need more compression to compensate for these thermal losses. JMO
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Old 01-09-2008, 11:33 AM
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they are a LOT easier to repair as well, should something unforseen happen.
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Old 01-09-2008, 02:27 PM
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Article on HP made with same head in Iron and Aluminum.
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Old 01-09-2008, 05:05 PM
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...AND it's real easy to cross thread the spark plugs! ...AND they cost bu-co bucks!
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