[Diy_efi] LPG injection

[sy2th]

Well, maybe I need correcting also, but that makes absolutely NO sense to 
me.  "Freeze" meaning ices up?  Where does the water come from?  It would 
have to be in the gas for that to happen, and lots of it.  Nitrous comes 
out of the nozzle every bit as cold as propane, never heard of any 
'freezing' problems.  The LPG systems I've seen draw vapor from the top of 
the cylinder, not liquid from the bottom as nitrous systems do, so what 
gets cold is mainly the tank & the delivery line.  Remove the nozzle from a 
propane torch & open it, aimed @ your hand - not real cold at all, but the 
tank chills.  Now, invert the tank, so's liquid comes out - - bit of a 
different situation, no?  Somehow, I don't think so, Al.....

Barry - Sy#26  -  (but, hey, I'm no expert.....)
Bangor, MI

At 10:19 AM 11/18/02 +1100, you wrote:
>Glynne,
>         I stand to be corrected, but from what I understand there is one 
> major hurdle which has dogged the concept of LPG injection. And that is 
> the "Latent Heat of Vaporisation" of the LPG. The reason is that liquid 
> fuels are injected as microfine droplets, but still a liquid however when 
> you try to inject LPG it submilates, IE it turns directly from a liquid 
> to a gas. To do this it absorbs heat from the surounding structure(metal, 
> air, etc) - large amounts of heat - much more localised cooling than the 
> waste heat into the area from the combustion chambers - and tends to 
> freeze the injector - literally freeze it solid (either open or closed!) 
> - thus end of control, BIG problems! This problem may have been solved, 
> but to my knowledge has not yet been. This is obviously a much more 
> fundamental issue to resolve before considering an ECU!
>Regards
>Bill W


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