Fuel vaporization has long been since carburators first emerged. Some designs used electronic fuel evaporators located between the carburetor and the intake manifold to heat the air-fuel mixture to insure vaporization at start up during cold weather. These vaporization systems only ran for about two minutes to allow for leaner choke calibrations.
Since the advent of fuel injectors, vaporization has been replaced by atomization of fuel by forcibly pumping it through a small nozzle under high pressure. The difference, according to Bushnell, is that vaporization uses heat instead of pressure to expand the volume of the atomized fuel mix--the key to reaping simultaneous fuel economy and lower emissions.
Bushnell's first task was to discover the limitations of previous fuel-vaporization designs. What engineering teams missed, according to Bushnell, was the increased volume associated with using superheated air. Instead, previous fuel vaporization techniques merely super-atomized fuel mixtures so they used less fuel, but increased emissions by burning too lean.
"Previous vapor fuel technologies have been based on the lean-burn approach," said Busnell. "But that creates a problem with oxides of nitrogen--NOX--which is one of the emissions that the EPA tests for and strictly limits."
Vapor Fuel Technologies' approach, on the other hand, avoids lean burning by instead heating both air and the vaporized fuel to near the point of spontaneous combustion, called auto-ignition, "which is a faster more powerful combustion event," said Bushnell. "So you can put less fuel in, and get the same performance by improving the combustion event, which is one of the big differences between our performance versus previous vaporization efforts."
The same fuel mixture enters the engine, but because hotter air occupies more space and provides more power, it enables a simultaneous savings in fuel economy and lower emissions.
"We have figured out a way to thermally reduce the amount of fuel in the mixture, rather that just put less fuel and more air. We heat the air and thermally expand it, so it literally occupies more space per pound--another way of putting less fuel in the engine, but without creating the lean burn problems." said Bushnell.
Besides offering retrofits for existing vehicles, Vapor Fuel Technologies is also negotiating with U.S., European and Asian automobile makers that plan to license the technology to increase the fuel efficiency of new vehicles. The company estimates that its technology can be added to new vehicles for less than $100.