Valve guides are one of the components in the engine that are subjected to a hard thermal and mechanical stresses. There are 3 specific types of valve guides, and they are :
Mono-metallic Valves - Produced with the idea of hot extrusion process or stamping process;
Bi-Metallic Valves - Make as possible to use the perfect combination of materials, both for the steam and the head;
Hollow Valves - This Valve guide have a particular use that it helps to reduce the weight and also reduce the temperature. Filled with sodium, the shaker effect of the sodium means that heat can go from the valve head to the valve stem, after this the temperature reduction of between 80°C and 150°C can be achieved.