The type of cylinder head that you have in your engine can mean a lot when you're measuring performance. Cast iron and aluminum are two of the materials that these heads are made out of, and there is debate among car enthusiasts as to which is better. While each has its advantages, aluminum has some specific, strong advantages.
Aluminum is a lighter material than cast iron, and when you consider that the mass of the cylinder head is the same in both instances, the aluminum heads are going to be much lighter in weight. This might be a small deduction, but when you're considering trying to get as much speed and power as possible out of a vehicle, all the weight you can take off is important.
Aluminum might not be as structurally strong as cast iron is, but when it comes to temperature changes, aluminum can better roll with the punches. Cast iron is prone to crack, and it's considered a brittle material in comparison with aluminum. When you're inside an engine where temperatures can change very quickly, that's an important consideration.
Aluminum cylinder heads can be machined, giving them the capability to be made to very exacting specifications. Additionally, it means they can be changed and altered by those with the proper machine tools. Cast iron has to be cast in a mold, and it is a much more difficult material to alter and change in a home workshop than aluminum.
Aluminum cylinder heads are easier to repair and cheaper to buy. There are arguments mentioned on the website DifferenceBetween.net that contend cast iron heads will endure longer and so they don't need to be changed as often as aluminum heads, but it's still a harder job replacing cast iron than it is replacing the aluminum heads.
