thanks for all your inputs. I thought creep might have been an issue, but i didn't think that it kicked in until 260 degrees celsius. I might have been using the wrong numbers though.
What are the main problems with using magnesium for cylinder heads? It is much lighter than aluminum, and has a thermal expansion close to that of aluminum. Aprilia has made a cylinder head out of magnesium, but no one else seems to want to take advantage of the much lighter weight.
