Yeah, freedom of speech applies to all... so who gave you the authority to question why he's posting?
I see exactly what he's saying... the small size of the squish area, combined with the average motility of even the largest fuel molecules, combined with pressure being higher than the condensation point of some of those fuel molecules, combined with the relatively cooler surfaces of the liquid-cooled head means some of the fuel will condense on the surface (probably not just the head... most likely also on the cylinder wall above the top ring... which, if you'll remember, is a significant contributor to UBHC emissions).
By injecting water vapor, which has a lower condensation point than the fuel, the water will condense on the surfaces before the fuel will. When the fuel condenses, it's sitting on top of the water molecules. As the water flashes to steam due to the advancing flame front, it pushes that unburnt fuel back into the flame front, thereby burning it.
In fact, that's exactly what I've been thinking. I'll be dropping a new ECU into my bike to control water heating and injection to test this, after I get the new ceramic-coated head and piston in, which will take place directly after I get done putting the new hybrid ceramic bearings and taller rear gears in.
As for his stating that most of the fuel burning takes place after TDC, he's yet again correct. Most of the fuel burning (and hence expansion) takes place after TDC. If it didn't, there'd be no available power. Or weren't you aware that engines are specifically designed such that maximum expansion takes place from 20 to 45 degrees ATDC (depending upon the engine), to maximize the mechanical efficiency of the pressure pushing against the piston? That
is, after all, why pressure peaks ATDC.
Think about it... if, say, 55% of fuel were burned BTDC, and hence 55% of expansion took place BTDC, the engine would have to extract flywheel energy to overcome that expansion... it's not contributing to driving the flywheel in the correct rotational direction.
The last 45% of fuel burn (and hence expansion)
would contribute to driving the flywheel in the correct rotational direction... except you've now got a 10% energy deficit at the flywheel.
Perhaps if you unblinded your eyes and learned simple math, you'd realize these things... and hence you'd not feel compelled to question those such as Peter who apparently have a firmer grasp upon the basics of combustion than you. And you'd not be so nasty to them that you then ran them off the forum.
Perhaps it's you who should go... do apologize to Peter and invite him back when you do so.
HTH, HAND
Oh, look:
MOTOR Magazine Article | MOTOR Information Systems
"Heat transferred to the induction charge should be enough only to improve evaporation of the
fuel to avoid
condensation on the bore walls."
Oh, look:
Cylinder head design
"The wedge-shaped combustion chamber tapers away from the plug which is at the thick end of the wedge. The valves are in line and inclined from the vertical. This design usually has a smaller surface area than the others, with less area where
fuel droplets can condense. Less fuel is left unburned after combustion, which reduces hydrocarbon exhaust emissions."
Seems someone owes someone an apology for being too dense to understand what someone was talking about, instead lashing out and driving away an innovative thinker from the forum.
Of course, Peter not only showed you the graph of fuel burn rate per degree, he also did the math for you to show you why fuel molecules can condense... and you still didn't get it. So I expect you'll try kicking like a mule again.