Head?
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Joined: May 2003
Posts: 11,141
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From: south louisiana
Originally Posted by Redtires019
This is also why you can generally run 1/2 a point to 1 point more compression with Aluminum heads that with Cast.
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Postmaster
Joined: Mar 2005
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From: Earth
Originally Posted by Redtires019
In a world with all things being equall (port flow, compression, valve size, ect) an Iron head will make more horsepower. The internal combustion engine essentually runs and makes its power from heat. Only abt 30 to 40 % of the heat generated is used by the engine. The rest goes out the exause or into the radiator. The better you can "damn" up the heat inside the cumbustion chamber, the more power you can make (that is until things start to melt 
). This is where Aluminum has a slight weakness to cast Iron. Aluminum is a better conductor of heat than Iron is. It will transfer more heat away from the combustion area. Therefore all things being equall you will see a slight loss of power on Aluminum vs Cast Iron heads. This is also why you can generally run 1/2 a point to 1 point more compression with Aluminum heads that with Cast.
In the real world things are never equall and where the aftermarket heads really excell is in port flow. They just are able to get more "Breath" than a stock set of cast iron heads.
). This is where Aluminum has a slight weakness to cast Iron. Aluminum is a better conductor of heat than Iron is. It will transfer more heat away from the combustion area. Therefore all things being equall you will see a slight loss of power on Aluminum vs Cast Iron heads. This is also why you can generally run 1/2 a point to 1 point more compression with Aluminum heads that with Cast. In the real world things are never equall and where the aftermarket heads really excell is in port flow. They just are able to get more "Breath" than a stock set of cast iron heads.
Anyway, if it's in your budget aftermarket aluminum heads are the easiest bolt-on hp you can find if you've got factory cast heads on your engine now.
Cross-Country
Joined: Jul 2007
Posts: 79
Likes: 1
Originally Posted by BaronVonAutomatc
I've got to disagree with you here. It's the rapid expansion of combustion gasses that makes an engine run. Heat is merely a byproduct of the combustion reaction/explosion than drives each piston downward on the power stroke.
Anyway, if it's in your budget aftermarket aluminum heads are the easiest bolt-on hp you can find if you've got factory cast heads on your engine now.
Anyway, if it's in your budget aftermarket aluminum heads are the easiest bolt-on hp you can find if you've got factory cast heads on your engine now.
Heat aka the burning of the fuel causes the rapid expansion of gases that creates power. If a part of that heat is lost out of the combustion chamber (via a metal that transfers heat better aka Aluminum) then you will likewise lose some power.
This is why some race teams have experimented Ceramic coating of the piston and heads. If you can block the heat from leaving, the engine will show a power increase. This technology has been used on some racing pistons for years and is dyno proven. You can damn up the heat in the cylinder and show a power increase until you reach the point that your parts cant handle it. The first to go is usually the exaust valve. If "Heat" had nothing to do with horsepower, then ceramic coating would not show a horsepower gain.
Here is an article on The benefits of thermal daming the combustion chamber.
http://www.replikamaschinen.com/arti...n%20Redmon.pdf
Cross-Country
Joined: Jul 2007
Posts: 79
Likes: 1
Originally Posted by HemiEater
WOW.... I always thought the cooler the more HP...
anyways why do you ask?
anyways why do you ask?
Cross-Country
Joined: Jul 2007
Posts: 79
Likes: 1
Originally Posted by HemiEater
I alway thought the cooler you make the chambers the more air and fuel you can get into them.
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