US Patent 7658171 Fuel tuned variable valve timing

A system and method for fuel tuned variable valve timing is disclosed. The system includes a plurality of cylinders, each cylinder being further associated with at least two exhaust valves. A first exhaust valve operates according to a first valve lift curve that is tuned for combustion of gasoline. A second exhaust valve operates according to at least two different valve lift curves that are tuned for E85 fuel. The second lift curve is associated with high engine speeds and the modified second lift curve is associated with low engine speeds.