In the recent Race Engine Technology article on valves, there was some discussion of the merits of hollow valves, and indeed the subject has been covered by Anne Proffit and I in these Monitor articles in the past. We should briefly restate here the reasons for hollow valves. The first and more obvious reason is mass reduction in cases where a reduction in stem axial stiffness does not compromise the proper action of the valve or present problems through lack of bending stiffness. The...

There is little doubt that, in many ways, steels have improved markedly in recent years. Fatigue properties in particular have seen a large improvement owing to better steel cleanliness. However, it is not only the cleanliness that affects fatigue behaviour, but the processing of the steel, and this processing introduces anisotropy into the steel. Anisotropy is the effect whereby mechanical properties vary according to the direction in which they are measured. By the use of directional...