[Diy_efi] LPG vapor injection with gasoline injectors:calculatingfuel requirements

Gary Spooner automotivelectronics
Sat Jun 10 03:49:00 UTC 2006


It would be difficult to create conditions within the engine for combustion 
of gasoline vapors (manifold injection). The problem is vapor point of 
gasoline versus propane. Here is a suggestion that would work. High pressure 
direct injection of fuel into a combustion chamber pocket exhausting into 
the area above the piston. Have ignition occur slightly late of the point of 
injection to allow combustion of the spray being localized at that point and 
preventing the conditions for unstable combustion which do occur where fuel 
ratios/temperature are not always consistent Flame travel and peak cylinder 
pressures are a factor with this design because of the latency of total 
combustion (piston outruns flame).  Just a few thoughts about the mechanical 
side.

Design a high pressure fuel system and maintain head pressure. Step up fuel 
pressure @ point of injection to further increase atomization the theory 
behind that is simple. Expose the fuel to as much oxygen as possible paying 
attention to flame color. This is where the next version of computer 
controls comes into play.

Drop the 02 sensor. This technology offers after the fact opinions of what 
is going on inside the combustion chamber. I have never appreciated the 
parallel feed of multiple combustion chambers into one pipe and sticking a 
02 sensor to sample a boundary layer of exhaust. I suggest have the computer 
verify combustion by analyzing light emissions generated within the 
combustion chamber during the combustion process. Each chamber fitted with 
the device and the computer given the ability to correct injection pulse 
width for each chamber. Imagine the diagnostic capabilities for this design.

Code P0387564 (lol) #3 cylinder irregular flame front travel observed..


The chamber temperatures would increase making it a requirement to maintain 
EGR but that is okay. OR! Even variable valve timing to lower peak cylinder 
pressures before compression. Hell with it, lets go 2 stroke!

G.Spooner/rpm-research.com

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