US Patent 7533641 Poppet valve and engine using same

One embodiment of the present invention provides a poppet valve offering an increased valve area, comprising an outer valve head comprising an outer valve port and an inner valve head comprising an inner valve port. The inner valve head is rotatable relative to the outer valve head to align the inner and outer valve ports to open a path through the poppet valve, thereby increasing the effective valve area of the poppet valve. The path created by aligning the inner and outer valve ports can be designed to mix air flowing into a combustion chamber.