What about the casting process?
Terms like Sand, Investment and Permanent describe the types of casting processes. The investment cast process can produce a great "cosmetic finish," but control of critical metal cooling rates in the investment process is more difficult than with the other processes and, if the cooling rate is not controlled, undesirable properties can result. The Hard Fact is that this more expensive investment cast process does not result in a better product. Any suggestions that it eliminates porosity and cracking are just plain false.
Continental uses a special combination of sand castings and permanent mold castings more accurately called "semi-permanent mold casting." The geometry of the cylinder head makes it a natural for this process and using it actually results in better material properties in critical areas of the cylinder head. The permanent mold tool in the critical internal dome area is water cooled to allow control of the aluminum cooling rate during casting. Exceptional material elongation and strength result in the most needed area. In addition, the rougher surface texture formed on the exterior of the cylinder by the sand mold process promotes more effective cylinder cooling.