DEVELOPMENT OF VVT TECHNOLOGY

Honda broke the ice when the NSX debuted in 1991 as the first production car with a variable valve timing system. Honda's VTEC (which sort of stands for Variable valve Timing and lift Electronic Control) system, which has basically remained unchanged since then, is still one of the most effective systems for making ultra high specific output. Ferrari has a really neat way of doing this. The camshafts on some Ferrari engines are cut with a three-dimensional profile that varies along the length of the cam lobe. At one end of the cam lobe is the least aggressive cam profile, and at the other end is the most aggressive. The shape of the cam smoothly blends these two profiles together. A mechanism can slide the whole camshaft laterally so that the valve engages different parts of the cam. The shaft still spins just like a regular camshaft, but by gradually sliding the camshaft laterally as the engine speed and load increase, the valve timing can be optimized.