Transform combustion to maximize output while minimizing pollution.

For engines, the licensing cost to manufacture intakes is $100 U.S. for each liter of engine capacity or $100 x (liters of air per minute at maximum output / 2500 liters of air per minute) for other uses such as furnaces.  The first ten manufacturers to adequately publicize comparative results get the first $100,000 worth free.

Variable.  One gets a saving right away from not having to utilize pollution abatement devices such as catalytic convertors. Depending upon how close to optimum the output is otherwise the fuel savings can be considerable.

    No.  Though it is better for any variance to be towards a lean mixture which wastes a bit of energy heating air that does not assist in producing energy than to have the less efficient rich mixture which exhausts carbon monoxide and can have soot build up requiring more frequent maintenance.  [I do note that sometimes the additional power from producing two CO molecules instead of one CO2 may be needed despite the decreased fuel efficiency and increased pollution.] 

The length of the intake required depends upon the vaporization characteristics of the fuel used and the temperatures of the fuel, the air and the intake.  Heating the intake may be recommended.  Very light fuels may only need a short intake and no heating, whereas the heavy bunker fuel used for ships and large stationary power plants may require a very long intake as well as the fuel and/or intake be heated quite a bit to insure vaporization of the fuel. 

Nearly all combustion devices utilizing liquid fuels and gaseous air can be throttled using the clean exhaust resulting from maximized combustion resulting from fully vaporized and mixed stoichiometric fuel to air.  Solid fuels 

  As vaporization is affected by temperature, the colder it is the longer the intake must be to insure full vaporization.  This can be ameliorated by heating the intake (perhaps having exhaust heating the intake wall).  Note that the colder the fuel-air-recycled exhaust mixture is, the denser it is, allowing more of it into the combustion chamber.  Water injection will cool the mixture, helping to produce more power. 

 Having fully vaporized the fuel before the combustion is over and by having enough oxygen to combine with the fuel the exhaust does not contain clumps of partially burnt carbon (soot).  Instead the exhaust is 'clean' consisting only of nitrogen; carbon dioxide; water vapor; argon and the minor traces of other things that came in with the air and fuel.  Thus no carbon to deposit. 

 Yes,. Having an intake filled with a mixture of fuel and air IS a danger.  Proper design, construction and maintenance will prevent it from being ignited before getting in the combustion chamber...but things do happen.  Thus it is strongly recommended that not only the throttle valve be designed to close and block any sudden backfire from passing fire past it into the intake, but that the intake be designed so that if there is such an ignition in the intake the force of the explosion be directed in safe directions. 

  The setting for the mixture (delivered by carburetor or injector) can be adjusted for air flow depending upon the reading given by a mass air flow sensor for incoming air or by an oxygen or other sensor checking the exhaust for proper  combustion constituents.   

  Yes.  The intake should be designed to properly handle the heaviest fuel it will use and the fuel-air mixture should be adjustable based on the incoming fuel. 

  Theoretically none, if properly designed and built.  This would require using sensors to calibrate a prototype.  While this would work for lawnmowers and smaller engines, for larger engines it is suggested to have sensors that measure intakes and/or exhaust  to insure optimal stoichiometric fuel to air ratio.