Posted by Jack Cain on Thursday, November 13, 2003 at 9:35AM :
In Reply to: They look good...... posted by mannyc on Thursday, November 13, 2003 at 8:57AM :
I don't know about the aluminum heads for a flathead but production aluminum heads have been used sucessfully for a couple of decades now without much adverse affect.
Perhaps it is due to better engineering or alloys. Also aluminum heads allow you to up the compression a couple of points above steel heads without incurring detonation.
The main advantage of increased compression is not so much a power increase but an fuel efficiency increase. The difference in power output between an engine at 9 to 1 compression and one at 11 to 1 compression is only about 6%. However the fuel efficiency of the 11 to 1 compression engine is about 20% above that of the 9 to 1 compression engine.
I have the engineering tables to support this as fact in case anybody wants to dispute this assertion with an anecdotal observation about being able to "feel the increase in power in the seat of their pants".
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