What's the appeal of an aluminum engine block?

[Phx Mike]

Originally Posted by RodKnock

It begs the question. Why isn't there a single new FE block anywhere? Was there a run of purchases (demand outstripped supply) and sellers were caught off guard? Are there manufacturing problems at every foundry? Or are the foundries really not interested in making 50-100 blocks per year when they have other larger orders that are higher priority because of size and fixed contracts.

From Brent's remarks, the lack of blocks has been a year long problem. These really are just rhetorical questions, but if I were building a Cobra, Mustang, Fairlane, I'd be a little upset because 352's, 390's, 427's and 428's just wouldn't do it for me at the prices these engines sell for.

Aluminum sand castings are difficult - period. The weight saving benefits due to the superior strength to weight ratio of aluminum vs iron makes it an essential element in a modern car (fuel economy). But the big guys (OEM's) are able to spend a lot of time and money optimizing the part designs and casting processes to improve the yield of the parts. They have to do this in order for the economics to work (you can't survive the cost impact otherwise). It is more than just the alloy used - aluminum is poured at much lower temps than iron or steel or titanium castings and it cools quickly. If the mold designs and temp and the pour process are not perfect, you get splashing, asymmetric cooling and all kinds of other issues that result in voids. Some times you don't detect these voids until you start machining the casting and get a break-out. I see this in the aerospace industry also. Sometimes you can get 100 good parts in a row and then something very subtle changes and you can't seem to get a good part. Very stringent process control in the foundry is needed to minimize this. It is hard to justify this when you are making a few hundred parts per year.

None of this is the fault of or can be controlled by the engine builder. The foundry processes and basic part design are the drivers.