Recenty I had the opportunity to get the old 2-burner Coleman gasoline stove out. You know how the kind you pump to pressurize? Well, the fuel line runs over the burner so that the gas is vaporized prior to burning. Before it heats up sufficiently, you turn a valve UP (to mix in air); after its good and hot DOWN to run on straight gasoline.
Always burns with a clean, blue flame; generally takes soot OFF pots and pans.
I also remeber hearing here that the big pollution issue is undissolved aerosol gasoline; IC engines that run on propane or natural gas have virtually no pollution.
Putting 1 and 1 together, why not pre-vaporize the gasoline by passing it inside the exhaust manifold? You’d (seemingly) get the pollutions benefits of CNG without conversion and fuelling issues? (I APOLOGIZE that this site does not allow me to input paragraph breaks ?!?)