transmission

[Boydskyking]

I was looking at some transmission the other and ran into the writing on some of the trans that they were chilled casting or die casting without armature. Does anybody know what this means?
Thanks

[Dave at Pelican Parts]

I don't think any regular 914 transmissions had those inscriptions on them. Regardless, I will try to answer your question without going into too much depth.

Chill casting generally means that part or parts of the mold are cooled to ensure that the cooling proceeds in the way that the metallurgists want it to, in order to make sure of specific material properties. (Strength, hardness, grain structure, etc.) Sometimes the "chill" is part of the casting itself, not the mold, but the idea is the same.

Die casting means that there is a metal form for the molten metal to go into in order to make a shape. Without armature probably means that there isn't excess metal stuff inside the form to make the shape stay put.

I think that most Porsche transmissions and crankcases are die-cast. Some early ones are sand-cast (there is a form made out of a special kind of sand that the molten metal is poured into to make the shape) but I believe most are die-cast. I believe that die-casting is generally less expensive than sand-casting when making large numbers of things.

I don't know which if either would be better for engines and transmissions.

--DD