http://seattlepi.nwsource.com/soundo...ommentID=31674
Comment to review:
Yep, looks like they shot Atomic Dog all right, Cap'n...

Been running propane for six months now, and it feels good. No
difference in the Jeep's power,and gas mileage (so to speak) is
slightly worse as propane has a lower energy content.

When I first start the car, it runs on gasoline. This is so it can warm
up the engine enough to evaporate LPG (Liquid Petroleum Gas - mostly
propane, some butane, pentane, etc). Part of the conversion kit is a
"converter", which takes the liquid propane in, uses the car's radiator
coolant to phase-change it to gas, then regulates the pressure of the
propane gas going out, and senses when pressure is low. (out of
propane) The gas then goes through a filter, and to the propane
injectors, which shoot it in next to the gasoline injectors, at the
right times.

The LPG computer monitors and controls everything, including the
signals from the Jeep computer controlling the gasoline injectors. The
propane computer puts up a whole charade for the Jeep computer, to make
it think that everything's OK and it's still running gasoline, when in
reality it's running propane. This way, the Jeep computer doesn't get
upset and fault. Since the Jeep's computer cuts out the gasoline
injectors and controls the propane injectors using the gasoline
signals, all the factory power curves are used, and all Jeep
compensations made, as for altitude, cold weather, etc. The LPG
computer also fools it into advancing the timing by 20 degrees, as
propane burns slower and the flame-front must be allowed time to
propagate fully.

Anyway, when the engine gets warm (~2 minutes), the LPG computer cuts
everything over automatically,and there's no detectable change in the
running engine. As long as the engine's warm, I can start/run on
propane the rest of the day. When I run out of propane, the LPG
computer senses this and automatically cuts me back to gasoline, and
beeps a warning. I can be on the freeway at speed when it cuts over,
and not even feel it in the engine. I have three 10 gallon forklift
tanks in the back, manifolded together, so 30 gallons capacity; plus
the original 20 gallons of gasoline. Although I never fill gasoline
beyond 1/4, as:
- I use so little it would go bad;
- Don't want the extra weight.

As I know some electronics, I've added a relay so that when on
gasoline, my dash gauge reads that, and when on propane, the gauge
reads that. Only problem is, the Jeep computer's anti-slosh software
causes a delay of ~15 minutes in updating the gauge when it switches.
It thinks my fuel switch is just the gasoline sloshing around, so it
delays updating.

I could get more technical, but this may be more than you wanted to
know in the first place, and I'm sure I've already bored others to
tears.

As you know, the conversion kit costs $2,500, but with propane over a
dollar less than gasoline now, it will pay off quicker than I thought.
And when I'm done with this car, I'll remove the kit and put it on the
next car; the old car still runs gasoline. At Autogas in Burnaby, I saw
trucks running on propane kits that were 20 years old. Exhaust was so
clean...

I have pictures, but can't post them here.

Here's the system I have:
www.prins-lpg.com/en/products/vsi/index.
html

And here it is installed by a German guy on his car (please bear with
the hilarious machine-translation):
babelfish.altavista.com/babelfish/tr?lp=
de_en&url=http%3A//www.njumaen.de/t4tt/l
pg.html