Wikipedia says that the melting point of copper is "1984.32 °F" while aluminum's melting point is "1220.58 °F". (different alloys of either would be different ). Sooo, the question in my mind is would the 700ish deg difference be a problem ? I dunno, but something to think about.
roy
Roy, I would think that if the melting point would be a problem, we'd experience the same problem with the heads, correct?
There's also thermal conductivity that can play some roll in it, from what I understand copper has some 1/3rd better conductivity in hot state than aluminium. And Copper expands much less than Alu that with an alu gasket may impose some creep problem. A fiber gasket can allow a lot more shear movement than solid materials. Multi layer StainlessSteel gaskets can allow shear between the layers without breaking.
I'm not too worried about the heat conductivity, as both the block and heads are water cooled. The added expansion could be a problem, but could possibly work in our favor- if we could get the torque right, the expansion could possibly help with sealing. I think!
I would love to use a fiber, or multi layer stainless gasket, but cannot get anyone to make one for us.
Aluminum is a lot softer than copper-maybe too soft is the issue? It may be that aluminum 'loses it's shape' after being torqued with the o-rings digging into it?
From Wikpedia- lead has a hardness of 5HB, aluminum 15HB, copper 35HB, and mild steel 120HB
So, some motorcycles run aluminum head gaskets, and a lot of cars have aluminum header gaskets. Does anyone know why aluminum isn't, or can't be used for head gaskets?
...Sorry, I don't necessarily always buy into the "if it worked, everyone would be doing it" thing!