[Diy_efi] RE: Diy_efi Digest, Vol 1, Issue 506

[Mike]

We had a chap here in perth who did a CNG conversion for a Ford 
StationWagon and IIRC used bosch methanol injectors from a gas
pressure regulator. The tank ran at something like 2000psi so no
fuel pump needed. With CNG being mostly methane, there was no
evaporator but high pressure tank in back of wagon which could only
hold enough for half the normal cars distance, ie. Wasnt deemed
legal to have a large 2000 to 3000psi tank of methane so a smaller
one was used that was just within fire/legal limits. I think he works
for the local gas company - trouble is we couldnt do that as we
only get CNG piped from 100psi main to 0.5psi at the home, bugger
the politics ! They absolutely refuse to remove the 0.5psi combo 
regulator/meter and put in a 100psi flow recorder/meter instead.
That makes it woefully uneconomic to pump up from 0.5psi to 2000+psi
to make it viable. Also the fed gov. wouldnt get their excise on
CNG as they cant tax for use but have to tax for product etc hence
problematic delineation between home heating/cooking and fuel given
we pay about 50% per litre 'tax' for parity pricing etc.

rgds

mike


At 11:06 PM 1/11/03 -0700, you wrote:
>I wonder how well the GDI injectors would tolerate LPG... That could make
>for a mighty fine motor.
>
>Chris
>
>>surely you'd need much bigger injectors as your spray time per
>>engine cycle is less, or will you raise pressure or also spray
>>a little when the inlet valve is closed ?
>>
>>rgds
>>
>>mike
>>
>>
>>
>>At 05:35 PM 1/11/03 EST, you wrote:
>>>well im no EE but ive been working on a AVR based injector controller that 
>>>takes a ecm pulse and converts it into a sqeautnaily timmed pulse. im a
long 
>>>way away form having it built. but it can be done. and alot of CDI engine 
>>>desiels and the mitsu stuff are in fact rail controlled fuel pressue. but
>>its 
>>>more in the head return. the point of CDI isnt to spray fuel directly into 
>>>the cylinder. its to take advantage of the vaporazation from the heat of
the 
>>>chamber/and being able to time the fuel to stave off detonation with hgih 
>>>compresion ratios. a hot injector pintle will really help to atomize the 
>>>fuel. this will inturn make it easier to ignite of very lean mixtures. yet 
>>>again any GM ecm could be use with a bit of hardware development. then
again 
>>>for all the trouble it might actually be easier to just scratch build 
>>>something or use a design similar to the efi332 project. 
>>>
>>>  its all subjective. there alot of way to skin the cat. 
>>>
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>>
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>
>
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