greg
If you know ours are HCCIs we are half way . As for vaporization I think it has been UNDERSTATED.. In a two cycle HCCI with cranckase circulatio I strongly feel that fuel ha to be vaporized ENTIRELY around the conrod, since ONLY a 10% diluition of the lubricant will reduce at half its useful viscosity. So no way with bios and similar, they are rod destroyers since NO bearing can work without sufficient viscosity lubricants.
Now to the combustion "chamber", I guess none did conceive any HCCI with a chamber with a 20:1 diameter to height ratio, a monster of thermal inefficiency. Going to this tiny space possibly droplets collide on on the internal surfaces. They vaporize or coalesce before compression rises adiabatically the temperature up to the ignition. In this way it could be that unburnt fuel going out is simply what "washed" by coalescing the inner cylinder, another cause of wear, I guess. So I advocate a fuel that VAPORIZES as soon as possible, also if this could lead to a small reduction in volume efficiency . But it should be a little effect, if you assume a less than 1 to 10 weight ratio of the fuel to air, and remember that fuel vapour has a molar weight higher than air.
ugo