I know this seems to be popular in Canada (don't know why it's not here) and I'm intrigued. Has anyone here converted a gasser to run on propane or CNG?
I like my veggie benz, but I could do a propane or CNG-powered Grand Wagoneer......
Man, that AADD is striking again!
Never done one myself, but there was a guy local who had an AMC Matador wagon that ran on propane. It had a really large cylinder, probably close to the size of a 60 gal compressor tank.
That cylinder was mounted on the roof. 
It was terrifying to see it doing 75 down the highway with a bomb on the luggage rack.
There are all kinds of CNG systems available for forklifts, a lot of those used what looked like a Ford/Motorcraft 2bbl carb. That would make doing a Wagoneer easy.
Back in the 90s Dodge sold Ram vans with CNG, just have to start searching C-list.
I had a converted CNG Chevy Pickup.
It was underpowered, and got terrible fuel economy. The fuel was more expensive than gasoline, the bed was half full of the compressed gas cylinder, and it was inconvenient trying to find somewhere to buy fuel.
Other than that it wasn't a bad truck.
I work in the forklift industry, and although ICEs are not my specialty, I see enough of them to have a firm opinion about LPG fuel systems. They are great for forklifts and even better for forklift mechanics, but would suck for cars, unless you were driving your car inside a warehouse at low speeds all day.
The main reason that LPG & CNG are in use as motor vehicle fuels is for reduction of HC CO & NOX emissions. Its not a cheap or convenient fuel, its combustion temperature is higher than gasoline which leads to burnt exh valves in some engines. Also not all LPG fuel is the same. LPG fuel for use in motor vehicles needs to be HD5 spec, the stuff sold for BBQ grills and home heating is different, with a lot more impurities in it that will ruin LPG fuel systems parts alarmingly fast.
NOX emisions NNOX
It hasn't been popular here for 25 years or more. There used to be tax incentives associated with it, but propane got expensive, and that pretty much killed it. Natural gas took over in the 90's, but it's mostly gone too.
I had a 1989 Toyota 4X4 I bought new and converted to dual fuel a few months later. The place I had it done financed it through fuel purchases; they continued to charge me for propane, but at gasoline prices, with the difference going toward the conversion cost. I think it took me around 18 months to pay it off. I could change seamlessly between gas and slowpane, and I did save a lot of money on fuel at the time. I would usually drive on slowpane and if I hit a hill I would just flip over to gas for a minute. It was a 4 cylinder, and it took to propane really well, but the v8s at the time needed to be built for propane, with higher compression to see any benefit. There is less energy in propane, but you can run crazy compression if you dare, so you get some of the lost power back. I think here in BC, there was a government push to get people to use propane(local resource) and then as it became more popular the price of course went up until the cost per mile was close to the same as gas. I remember vicious propane price wars and I once went to Seattle for the Supercross with 3 friends in my pickup (4 hrs each way) and the trip cost me 5 dollars. I think I filled up at 5 or 7 cents a liter on my way home.
We had a bunch of full sized Chevy trucks at work that ran on propane. There is still one little Diahatsu with it. Sucks. In winter the gas compresses and it's a bitch to get a vehicle started. The only place to refill the tanks is five miles away.
YMMV.
Drove a CNG Crown Vic about 15 years ago. It was a limited release Ford production vehicle. It drove great...
Rog
Considered it and actually started gathering the pieces to do it. It's got great performance potentials, particularly the propane conversions. That's what I was interested in.
But the very limited ability to find refueling stations, and now the cost of propane. It was the extremely limited refueling ability that forced me to drop the project.
Conversions suck because they are not optimized to the fuel. Propane has the equivalent antiknock rating to 105 octane gas and NG is like 140 Octane (or close to those numbers). You can run big compression especially with NG, but that requires dedicated service - not switchable.
My previous employer had a Cavalier with the old 2.2 converted to NG. It was okay on a multi-lane highway, as a range extender, but your foot was basically in the throttle body. On a single-lane highway pulling out to pass on NG was a life-endangering prospect.
There are no fuels out there that offer the energy density of gasoline. The Cav I mentioned earlier lost half of the modest trunk to a NG tank, yet you might get 150 kms on that tank.
As Zomby said - there used to be big tax incentives in Canada to convert but they are gone. Most NG fueling stations and propane are gone too. So you are SOL for re-fueling.
There's one REALLY attractive reason for CNG.
Natural gas costs $2.70/MMBtu right now, wholesale. A gallon of gas has 120kbtu or so.
Therefore, the same amount of energy as a gallon of gas costs 35 cents. Even if you pay double that retail it's still 70 cents a gallon.
The major advantage for operation is the high knock resistance. The major disadvantage is the volume taken up by the gas. Therefore, any conversion candidate should be turbocharged - as you can really crank the boost up without any worries.
The newspaper I worked for, before they went diesel, had all the local delivery trucks set to run on dual fuel. That made for an easy 400 mile range for a 460 powered loaded down with 12k worth of paper. I even have the whole setup including the 55gal tank they used still..... Now to find the pre 97 460 Ford truck...
I used to have an LPG-converted Range Rover in the UK. LPG conversions are moderately popular in the UK and the Netherlands due to the much lower tax on the fuel so even if you use 10%-15% more fuel by volume you still come out ahead financially.
Given that a Range Rover Classic isn't exactly the fastest thing on four wheels anyway, the slight performance loss was very tolerable. More modern systems do tweak the ignition to make use of the higher octane rating and have a much more efficient injection system than the one on my RR, which makes a big difference to both power and fuel consumption.
CNG is awesome....if you can find a fueling station. The cost is 1/3 the equivalent units of gasoline. The crown vic was a popular dual fuel from the factory.
I used to work on a ton of taxicabs, and around here they were almost all converted to LPG. If you didn't try for the dual fuel, and never left the city, they were perfect. Slight loss of power, which could be compensated for with compression, but the 305 Caprices never wore the engines out. I saw lots with well over 500,000 km, a couple with a million km on the original engines. I had one show up one day with an oil leak- the timing chain had stretched so much it had worn through the timing cover.
Off topic: Why do traditional small block chevs never jump the timing chain until all the teeth are gone? I had a Jeep jump with less slack than a new Chev would have had.
Anyway: Used to be lots of fill stations around here, but the cost of conversion went up when EFI became common, and the economy benefit started to drop, so it went out of fashion.
The Saskatchewan (or was it the National...)Research Council did a lot of work on natural gas, and I know some of those guys. It works ok, but storage is really the big issue. Propane liquifies at fairly low pressure/temp (at -35C, you can carry an open pail of propane) but natural gas has to be stored as a gas, and to get any kind of volume, the pressures are very high- over 2000psi, if memory serves. Ford used to make trucks at the factory with CNG fuelling, but they stopped a few years ago. I have a friend that works for the local gas utility, and they have Chev vans with conversions. They are OK, but not as seamless as the factory installation, and the payback is forever- I think its over $6k for the conversion now.
I'd bet you can find used propane stuff pretty easy, if you want to look around. CNG, maybe not so easy.
Honda has/had a CNG Civic for a few years. Heard that they were/are very popular in either Utah or Colorado as fuel is super cheap, or has some tax advantage in those states.
