US Patent 7685993 Low cost variable swirl

Variable swirl for internal combustion engines. In one aspect, an apparatus includes a first intake valve controlling air flow from a first intake port to a piston cylinder of the internal combustion engine, where the first intake valve has a first lift profile. A second intake valve controls air flow from a second intake port to the piston cylinder, where the second intake valve has a second lift profile different than the first lift profile. The combination of first and second lift profiles causes a variable swirl of air in the cylinder as a function of engine speed.