CNG/LNG

[Seth Allen]

Hi all, I am a student at Western Washington University's Vehicle 
Research Institute. I joined this mailgroup to hopefully learn how to 
build an EFI system for gasoline, but the discussion seems to be EFI for 
gaseous fuels.  That's cool too...  we have a Chrysler Neon here that 
runs on CNG. It has a filament wrapped carbon fiber CNG tank. good for 
3600 psi maybe 4000, but we don't (can't) pump it that high.  It also 
happens to be an electric hybrid...  We ran 14.4:1 compression last year, 
but NOx emissions were high so we have stock pistons now. Right now we 
are "fooling" the gasoline EFI brain.  It goes tooo rich on full 
throttle enrichment and displaces air in the intake ports.  (We think). 
A fun idea would be to add Nitrous oxide.  Not too practical though. 
Having trouble with a gasoline O2 sensor on CNG and the heat required 
to run it.  It is a 3 wire O2 sensor, but the preheater isn't enough at 
idle.
  We are currently looking for a liquid fuel injection setup for propane for our 
propane minivan.  The current strategy is impco carbs.... Vialle didn't 
want to donate any propane EFI equipment, and it was unclear that they had 
an adaptable unit.

If anyone has any input or questions, just ask, or tell.

Thanks for the bandwidth,

Seth Allen

WWU, Bellingham WA, USA


> > While on the topic of CNG/LPG... > 
> There is a fleet of port injected CNG taxis running around in Brisbane, 
> Australia as well as some in New Zealand.  For our single fuel application, 
> the compression ratio was raised from about 9:1 to well over 15:1, and the 
> resulting peak efficiency increased from about 30% to over 40%.  Natural gas 
> in Melbourne is relatively consistent (but not available in CNG form) with 
> a RON of 140-142.  In Brisbane and NZ the methane ratio can be as low as 90% 
> lowering the RON to about 130.
> 
> To test various methane / propane ratios, we recently installed a second set
> of gas injectors with an adjustable pulsewidth proportional to the base 
> injector pulse from the Ford EECV ECU.  Could this be the ultimate dual fuel
> combination?
> 
> The project was set back a little last week when the dyno drive shaft flex
> coupling decided to let go and hurl itself through the bell housing and
> steel safety cover, across the lab, through a window and into the car park
> onto an unoccupied Nissan.  Luckily no one was hurt, but the mechanical
> casaulties include the drive shaft, engine crankshaft, dyno shaft,
> bell housing (now lots of little pieces of aluminium) and safety cover.
> 
> LPG in Australia can have as much as 50% butane which lowers the octane rating
> to just under 100.  Unfortunately this is little better than the leaded fuel
> that about half the cars on our roads still use.
> 
> rambling on...
> Robert
> 
> -- 
>     Robert Dingli   r.dingli at ee.mu.oz.au
> Power and Control Systems    (+613) 9344 7966
> Thermodynamics Research Labs (+613) 9344 7712
>      University of Melbourne, AUSTRALIA 
> **  he who dies with the most toys, wins  **
>