[6869l89]

Did the "FACTORY" aluminum head motors produce more horsepower?
...or just save weight?
....or both?

 

[bulb122]

I guess it depends on which factory motors you're talking about. My buddies factory alum head 86 Corvette was a serious pooch. I'd say in that case, the heads only reduced weight....

 

[David Bates]

Typically, an aluminum headed engine will make less power than a comparable iron headed engine as they dissipate too much heat in the combustion process. Loss of heat, loss of power! The question you have to answer is will the loss of power be offset by the weight savings!

 

[troposcuba]

Typically, an aluminum headed engine will make less power than a comparable iron headed engine as they dissipate too much heat in the combustion process. Loss of heat, loss of power! The question you have to answer is will the loss of power be offset by the weight savings!

this is true assuming nothing else changed, but aluminum heads can tolerate about a point higher compression (due to the heat loss) than iron heads without detonation becoming a factor. so if you up the compression accordingly to put the power back in the same ballpark and lose the weight, where does that leave you?

 

[SS_Dave]

... so if you up the compression accordingly to put the power back in the same ballpark and lose the weight, where does that leave you?

.. arguing about rectangle or oval?

 

[6869l89]

I was speaking about an original 396/375 aluminum head motor....
...( with square port heads )

 

[supersport396_2000]

I found this on the net, from the above comments it can't be true.

From 69 specs

L78 V8 396 cid 4.09 x 3.76 375 @ 5600 420 @ 3600 1 x 4bbl. 11.0:1
L89 V8 396 cid 4.09 x 3.76 375 @ 5600 420 @ 3600 1 x 4bbl. 11.0:1

 

[David Bates]

I found this on the net, from the above comments it can't be true.

From 69 specs

L78 V8 396 cid 4.09 x 3.76 375 @ 5600 420 @ 3600 1 x 4bbl. 11.0:1
L89 V8 396 cid 4.09 x 3.76 375 @ 5600 420 @ 3600 1 x 4bbl. 11.0:1

Do you really think GM or any other manufacturer would charge extra for aluminum heads and tell you the truth that the engine will make less power? The above statements are true . . .period!

 

[-SS454-]

the GM 401 aluminum heads outflow their 990 and 188 heads if that helps. I dont for sure know about the factory 60/70s heads, but usually aluminum heads are better quality pieces in terms of port and chamber smoothness and thats noteable for power. Now days almost all aluminum heads are CNC machined and will make more power everywhere over a cast iron head thats supposed to be identical.