Originally Posted By 383man
Originally Posted By Supercuda
Originally Posted By Cab_Burge
The new aluminum heads will flow more air


Since no specific head was specified you can't say this.

Plenty of aluminum heads out there that are crap and need rework out of the box, I suggest you google speedmaster heads. So when some say " the cost pf rebuilding an iron head" as an excuse tend to not add the cost of making sure you aftermarket aluminum head is ready to run.

Nor is there any actually data supporting the aluminum allows higher compression claims. Combustion chamber design is the major factor in allowing higher compression, iron hemi heads can run just as high a compression as aluminum ones. Assuming your new heads have efficient combustion chambers you can consider increasing your compression ratio.




I have to disagree on the higher comp. Aluminum heads will disapate the heat faster which will allow you to run higher comp and not have detonation. Its a know fact thats also why most say you can get away with about 1 point higher comp with aluminum heads and not because of the combustion chamber design which I do agree the newer aluminum heads do have better combustion chamber design's. Ron


There is zero data to support your conclusion and "it's a known fact" doesn't count unless you can show the data.

Closest I have seen is that car craft did a iron to aluminum comparison with two otherwise identical aftermarket heads.

They tested the myth that the ability of aluminum to wick away heat would affect power output. Zero difference in power output.

They also detected zero issues with detonation, 10.88:1 comp ratio, using pump gas and speculated that maybe the compression ratio needed to get higher to see anything. But at that level there was NO difference in power or detonation between the two materials.

http://www.hotrod.com/articles/ccrp-0602-iron-versus-aluminum-cylinder-heads-test/

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