Brian is absolutely right as far as my understanding of the material difference goes. I can't see why all the big racers and billion dollar companies would use Aluminum when iron is cheaper. I also can't understand why you would think iron is advantageous when there are no examples of aftermarket iron heads that outperform the aluminum ones. I think the onus is on you, Bullitt, to demonstrate any evidence you have to the contrary, rather than expecting the community to simply take your word for it.
That said, I would just like to point out that "pre-ignition" is not the same as "detonation." It's a common misconception. One happens before the spark event, the other happens after. One is catastrophic to an engine, and the other could be, depending on the severity. Detonation is the term he meant to use.
That said, I would just like to point out that "pre-ignition" is not the same as "detonation." It's a common misconception. One happens before the spark event, the other happens after. One is catastrophic to an engine, and the other could be, depending on the severity. Detonation is the term he meant to use.
Here's an article that indicates that iron is certainly not better: http://www.carcraft.com/techarticles/ccrp_0602_iron_versus_aluminum_cylinder_heads_test/
The article seems to show pretty good evidence that ignition timing and air/fuel ratios remain the same, and that power does, too. It also recognizes that there may be the possibility of raising compression with the aluminum heads. I question that though. If the aluminums could handle more timing or a leaner A/F than I would be inclined to believe it.
I also question whether heat soak would make a difference in any non drag racing event.
The article seems to show pretty good evidence that ignition timing and air/fuel ratios remain the same, and that power does, too. It also recognizes that there may be the possibility of raising compression with the aluminum heads. I question that though. If the aluminums could handle more timing or a leaner A/F than I would be inclined to believe it.
I also question whether heat soak would make a difference in any non drag racing event.
This next article is kind of funny because after setting up a test that they assumed would show the superiority of iron heads and getting an "aluminum version [that] is almost a clone of its cast-iron cousin with the addition of CNC-ported combustion chambers," the results showed that the aluminum heads outperformed the iron ones, and their conclusion was that iron still makes more power, but not much! Are you kidding?
Ok, they have a point that the CNC port changed the shape of the combustion chamber, but they sure as hell didn't do a test that could lead them to any scientific conclusion, and again they did not test the effect of compression ratio.
Read more: http://www.chevyhiperformance.com/techarticles/83858_iron_vs_alloy_engine_heads/#ixzz2vTYSLDfa
Ok, they have a point that the CNC port changed the shape of the combustion chamber, but they sure as hell didn't do a test that could lead them to any scientific conclusion, and again they did not test the effect of compression ratio.
Read more: http://www.chevyhiperformance.com/techarticles/83858_iron_vs_alloy_engine_heads/#ixzz2vTYSLDfa
I always thought the cast iron VS aluminum cylinder head thing was kind of like the "stepping over a dollar to pick up a penny" logic. If there truly is any power to be had in iron, it's nearly negligible and it gets buried in the peripheral benefits of the aluminum head anyway. Look at the Engine Masters guys, they have no concerns with additional weight, yet they run aluminum heads anyway.
While the raw iron material may be cheaper than aluminum, there are a lot of other financial reasons that make aluminum more ideal use for car parts. Its melting/casting temperatures are lower, it's lighter, so it's cheaper to ship and requires lower-power equipment to move it around the plant and install it in the cars, and it's softer, so it's easier on the machining tools.
While the raw iron material may be cheaper than aluminum, there are a lot of other financial reasons that make aluminum more ideal use for car parts. Its melting/casting temperatures are lower, it's lighter, so it's cheaper to ship and requires lower-power equipment to move it around the plant and install it in the cars, and it's softer, so it's easier on the machining tools.
There was a reason I used italics when I said exactly. I never claimed it was vastly superior, or moderately superior. I just said it would always make more power. I did not say there were financial or production benefits to the cast iron head. I obviously understand the benefits of the aluminum head. Having ported literally hundreds of cylinder heads, it is so much more labor intensive to port a set of cast iron heads, that I really never want to do them again. There are some cast iron heads that are produced for performance use for certain racing series that require a cast iron head, but compared to what is available commercially, I would never use then for any of my racing or performance endeavors. My statement had more of a fine point to it, and it was obviously taken in a much broader context. But I stand by the statement.
I agree that aluminum is the superior material to use when you factor in the advantages in weight, machinability ect. And with the advent of thermal barriers being able to be applied to combustion chambers and piston tops, it is unnecessary to have to use cat iron as a material. I did not write a scientific paper on my results, and if I had, I doubt that it would have been accepted by the scientific community at large. All I can relate is my own empirical knowledge gained thru years of hands of experience. I know what I saw when I saw it, so to speak. Does it prove anything.............maybe, depending on your frame of reference.