Ok, I was sure I was misreading, plus I can't see squat on my phone.

This guy is going in the proper direction. He's building it the way he wants without asking what people think it should be.

I spent some time researching how billet aluminum is made. Most of billet is extruded at very high pressure at a temperature lower than melting point of the alloy. The pressure ensures there are no cavities in the metal. No wonder billet is costly to manufacture! The alloy is forced through a restriction in a continuous process and sections are cut away as it cools. The process is sort of like extrusion honing except its a solid material and much much higher pressure. There are other processes that make billet but all require extreme mechanical pressure. Billet will probably always be very costly.

the cost to get custom extrusion is actually very low as long as you buy a decent quantity. the cost of extruding billets is not signifigant to the cost. Aluminium is expensive because of the process to refine it. the price of aluminium is effectivley the cost of electricity. Aluminium ore is super cheap, and its everywhere, but you use a crap load of electricity to turn it into metalic aluminium. the next cost for billet machined parts is that most of the material goes back to the recycler as dirty scrap metal.

I'm not exactly following all this aluminum discussion....the bottom line is he (or anyone else) will pick up the phone and order a chunk of aluminum with which to make his part. He won't have any say in how it's made or where it comes from.....not when he's buying a few hundred dollars' worth. In using a 7000 Series piece of aluminum, he's not breaking any new ground or inventing anything...it's pretty much the normal material.

While it might well involve the extrusion process, it's a generic chunk of aluminum. Typically, in aluminum production the term 'extrusion' is used to refer to shapes far more complex than the square or rectangle.

The material is the least of his concerns in making a cylinder head. His two main obstacles will be the massive amount of stock removal (in all the right places) and the effort needed to incorporate water jackets.

My thinking was whether a block casting could be used instead of billet for the CNC work. "Probably", is the answer. The billet would be very high quality. Even a simple block cast can have porosity and castings usually don't weld as well as billet. But, if you melt scrap aluminum of a known source you have a good guess of what alloy was used. A local buyer of aluminum pays 20 cents a pound - I can't recall the exact number. But, if I pad $1.00 a pound I could get pretty much the best scrap cylinder heads. Assuming I could cast a rectangular shaped block of aluminum, then maybe 2 of 3 raw castings would be suitable for CNC work. After 25 of these castings were produced, have the CNC shop work on them. Assuming the casting was weldable, then minor defects can be corrected by welding. I'm thinking of how MacGyver might do it. Billet isn't a casting, but a casting can be decent and the finished head could be beefier than an OEM head so it might be less likely to crack and warp without the engineering costs of an OEM head.

That's it..

Be different.

A bronze head......………