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Converting to Propane


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19 replies to this topic

#1 dap

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Posted 16 September 2006 - 01:42 PM

I love my 1997 Outback but the gas prices for my commute to a property 400 km away is killing me. I have found a propane conversation place that says I can do it (duel fuel system), but another place I called says I shouldn't. Has anyone out there had any problems with it?

#2 ericem

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Posted 16 September 2006 - 01:50 PM

I would not use propane, natural gas i would think is good. Propane is to hot isnt it?

#3 dap

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Posted 16 September 2006 - 02:09 PM

I guess I'll ask my Subaru maintence people about that. Thanks!! (Wish I knew how cars worked! I just drive...)

#4 Megell

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Posted 16 September 2006 - 02:24 PM

I love my 1997 Outback but the gas prices for my commute to a property 400 km away is killing me. I have found a propane conversation place that says I can do it (duel fuel system), but another place I called says I shouldn't. Has anyone out there had any problems with it?


I have performed several gas engine to propane conversions in the late seventies and early eighties when I used to work for a high altitude, high performance propane dealer. First concern is where do you store the LP tank in an OB. Inside is out of the question Due to expansion/saftey issues. Outside would be "interesting, if you like pontoons". Most of my conversions were performed on pickup truck types and not fuel injected as all of todays cars and trucks are. Fuel tank location were mostly either in the bed of the truck and/or underneath the driver/passenger front door between the frame rail and body, tucked underneath the door.
Also consider that you loose about 20 to 25% performance without modifying the engine to compensate.
One other nice thing about burning LP is that there is almost no fuel contamination in the engine, which means longer life of the oil and the engine in general, especially if you use synthetic oil, and water vapor is much of the exhaust vapors, so LP is more earth friendly in that way.
Mike

#5 dap

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Posted 16 September 2006 - 03:18 PM

Thanks so much for responding. The guy I took it to said that there are two option, both inside the car. They now make donut shaped tanks that fit where your spare tire goes. The other is to put a 14" cylinder behind the back seat (losing access to fold down cargo). I don't know where your from, but here in Vancouver (Canada) propane conversions/duel systems are very common. Especially now with gas over a dollar a litre. I would have to do a duel because of the fuel injection system (I'm a girl and that sounds pretty impressive talk to me!!) and there would be a switch that would allow the engine (or manually) to switch fuels. He said with whatever gizmo they have now that it actually doesn't affect performance anymore. All the stuff I've read so far says that propane is actually safer than gasoline.

I'm calling another place (large propane company)that does a lot of car conversions on Monday and see what they say too. They use a German system (went on the German site and they showed an implemention on an Outback using the "donut" tank in the tire space). I'll talk to my Subaru dealer too. Otherwise I'm going to have to get a Jetta TDI! (oh no, I've had Subaru's since 1986). Thanks again.

#6 porcupine73

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Posted 16 September 2006 - 04:51 PM

Well first I would make sure you can make the 'business case' for this conversion. You must accurately calculate over the lifetime of the vehicle or how long you plan to keep it what your savings will be to go to propane vs. just stay with gasoline. Don't forget the time value of money at whatever percentage you think it is; you have to shell out cash up front for the propane conversion.

Propane conversions usually require a vaporizer tied in somehow to the engine coolant system so it doesn't freeze up. Not a big deal; your conversion would include one if it's needed.

Dual fuel propane is popular on diesel engines because of increased hp. Natural gas can be a little more tricky because the pressures in the tank could be like 3000psi as it doesn't liquify at relatively low pressures like propane does, thus making LPG. I would absolutely love to convert my vehicles to NG but haven't found a reasonable way to do it.

I tried a little propane experiment, just routing a little propane from those small camping cylinders into the intake just to see if there was a mileage incrase, sort of a synergy experiment. :banana: :)

#7 dap

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Posted 16 September 2006 - 06:11 PM

It's going to cost $4500 including federal tax. We get a provincial tax exemption for converting here. I'm self-employed so I'll write off a good portion of it. I plan to keep the car as long as it runs (currently has 160k) or until Subaru gets their act together and comes up with fuel efficient cars. I have a property in the mountains and ski all winter so need an AWD. Trade in value is only about $8000 maybe get $11000-12000 if I sell privately. Other cars eg. Jetta Wagon TDI with similar or lower milieage cost anyware from 17000-23000 (used) so this is my preferred way to spend money (or get a face lift). Cars up here in "Canada" are very expensive compared to the US (as is gasoline). Also a huge motivation is trying to be "environment friendly.

Thanks so much for taking the time to respond!

#8 porcupine73

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Posted 16 September 2006 - 06:21 PM

Sounds cool. What kind of self-employment do you do? What are the environmental advantages of running propane vs. gasoline? I don't think Subaru mpg is all the bad for being awd vehicles; there's lots of vehicles that are worse and of course lots that are much better like honda civic MT.

#9 Subarupusher

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Posted 16 September 2006 - 07:14 PM

I have used a government truck (GMC Sonoma with 5.0 Liter engine) with gasoline/propane for 10 years and 100K mileage. Engine seems as strong as the day they delivered the truck. There is a definite power drop off when running on propane and my city mileage averages about 15.

It did take a few tune ups for the first two years to get the engine to run the same on either fuel. It seemed like that it would either run rough on regular or propane depending on how they tuned it. Has not been a problem for years.

The tanks are easy on pick ups because they mount in the front part of the bed and have a cage around them. There was also a new tank developed in the 90s that allowed more than 20 gallons of storage. The first generation of propane tanks for our motorpool only had 10 gallon capacity and drivers would not switch over to propane since it seemed like they had to fill up almost every day.

Our motorpool is also not converting trucks anymore for propane probably due to the cost of the initial conversion and tune ups and getting the drivers to quit burning regular because it is more convenient.

#10 dap

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Posted 16 September 2006 - 08:09 PM

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Environmental benefits

Propane burns more cleanly than gasoline or diesel fuel. Its use produces fewer greenhouse gas emissions that contribute to climate change. The use of propane as an alternative fuel in factory-built vehicles can reduce greenhouse gas emissions by 20 percent in light-duty vehicles on a life-cycle (well-to-wheel) basis (compared with gasoline). Emissions reductions resulting from converted vehicles vary and are normally not as high as for vehicles built specifically to run on propane.

Propane also contains fewer toxic pollutants. For example, because propane has extremely low sulphur content, it does not contribute to acid rain. Furthermore, propane is a pressurized fuel that must be contained within a sealed system, right up to the time it enters your vehicle, so it is less likely to escape into the air, soil or water through careless handling, spills or evaporation. (From Environment Canada)

There you go. We're pretty environmentally conscious up here in Caanaadaa.

#11 Zefy

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Posted 16 September 2006 - 09:05 PM

my old auto teacher has all of his cars and trucks running on LPG... including the school drag car...

i quite like the system and i might also think about converting when i have the time and money...

so if you got a tank that goes in the spare tire spot, then where does your spare tire go?:rolleyes:finding a good spot for the tanks is kind of a challenge it seems... if you find a good way please tell us all... i would like to know!:)

and hey, if you do deside to get a TDI (i personally wouldn't do it!) come on down to westminster VW in Coquitlam... i work there...;) tell them Greg told you to come down... they like it when i do that...:rolleyes:

i stil say go for the LPG though!



#12 nipper

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Posted 17 September 2006 - 12:28 AM

Aside from fuel sotrage, this is a common comversion. Just realize that your "fuel" milage will not be the same as gasoline. But if the cost is right it may not matter.

http://www.cleanener...Quickfacts.html


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#13 Cougar

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Posted 17 September 2006 - 02:51 PM

I commend you DAP on your concern for the environment and if that is your priority I can see why you would want to do the conversion. You stated you are concerned also about costs of fuel to your pocketbook. By doing the conversion you will get less mileage from the car and have some high up front costs to do the work. I would have to wonder how many miles you would have to drive in order to just break even with the costs of conversion. How many liters would $4,500 dollars buy you? Even with tax breaks and less fuel costs included. It seems to me it will take you years of fillups to recover the costs of conversion. There are the added benefits of a cleaner engine and less oil changes though.

#14 Megell

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Posted 17 September 2006 - 03:18 PM

Well first I would make sure you can make the 'business case' for this conversion. You must accurately calculate over the lifetime of the vehicle or how long you plan to keep it what your savings will be to go to propane vs. just stay with gasoline. Don't forget the time value of money at whatever percentage you think it is; you have to shell out cash up front for the propane conversion.

Propane conversions usually require a vaporizer tied in somehow to the engine coolant system so it doesn't freeze up. Not a big deal; your conversion would include one if it's needed.

Dual fuel propane is popular on diesel engines because of increased hp. Natural gas can be a little more tricky because the pressures in the tank could be like 3000psi as it doesn't liquify at relatively low pressures like propane does, thus making LPG. I would absolutely love to convert my vehicles to NG but haven't found a reasonable way to do it.

I tried a little propane experiment, just routing a little propane from those small camping cylinders into the intake just to see if there was a mileage incrase, sort of a synergy experiment. :banana: :)


The "vaporizer" that you mention, I think, is called a "converter". It's job is to convert LPG to gas vapors (if memory serves) before it enters the "mixer" (carburetor) to feed the engine. It has two diaphrams and one side has engine coolant running through it to heat up the LPG gas which is then vaporized and sent into the other diaphram chamber which controls the "demand" before it enters the carb. or "mixer". The system also incorporates a "lock off valve" inline so that when you turn the ignition on, it allows fuel to the mixer.
It's been said that propane is safer than gasoline and I won't argue that point except that if/when it does ignite when it's not supposed to, it is much more explosive than gasoline. It also has a high specific gravity meaning the when propane leaks from a storage system it will fall to the ground instead of rising into and dissapating into the air, therefore making it more dangerous. I've seen RV mechanics loosing most of there hair and wind up with third degree burns just from the amount of propane in the line and ignite it just from laying on the carpet on the inside of a motor home. Static electricity WILL set it off. Again, my experience is a few decades old, so I don't know how much things have changed regarding conversions, but I can only assume that technology has advanced some of the systems.
Mike

#15 rverdoold

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Posted 18 September 2006 - 12:52 PM

Hi all, well sure America has a lot to learn form Europe about driving on Propane (or LPG).
In holland we drive on Propane or LPG for years without any problems. My dad's 05 OWB 2.5 has been built in with a LPG installation. The spare tire is replaced by a ring tank (65L) and an aditional meter is placed near handbrake or elswhere on the dash.

The installation is made by Koltec (http://www.teleflexgfi.nl/) using a Sequential injection system.
In italy subaru sells cars with an in-factory build in LPG system or CNG.

#16 grossgary

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Posted 18 September 2006 - 01:12 PM

i've heard other "gas" alternatives are escalating in price too, making conversion less cost friendly in the U.S. propane and NG varies wildly across different areas/regions. i know nothing about these conversions but have read alot about it. it's something i'd like to do but don't and will never have the time to learn it. i'd only do it myself for the learning aspect of it.

#17 cookie

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Posted 18 September 2006 - 02:53 PM

I've had a fair bit of propane, lpg, and dual fuel experience on fleets. I'm sure they must have licked the refirigerator problem we used to have heere at SFO. With the fog and cold at the airport if you did no high idle until it was warm the fuel system would freeze up like a propane refrigerator. I'd pop the cab and the engine would be invisable under snow.
More power to ya but except for the environmental benifit I doubt this will pencil out on such an old car. If you plan on moving the system to yur next car you might win in the end.
Just for interest CARB called Friday and offered me a hydrogen van for my shuttle program. We are getting a hydrogen station here in San Carlos and another at SFO. We are having a couple small busses converted to dual fuel, gas and hydrogen.
I've driven the hydrogen Toyota and the hydrogen Mercedes, they feel like a Prius.

#18 robm

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Posted 18 September 2006 - 04:14 PM

The price of propane is close to that of gasoline, when you look at the caloric value. Here in BC, about all we save is some taxes, maybe 20 cents/liter. 800 km round trip, at about 8 l/100 km approx., the savings would be about $12 per trip.

That saving can be eaten pretty fast if the propane mixer is not as efficient as the fuel injection system it is replacing. I don't have a good idea of the current state of the art. In the days of carburettors, propane mixers were at least as efficient, but I don't know if they have kept up to the mark. Are they feedback systems now, adjusting the mixture depending on the O2 sensor?

This reflects directly on the environmental aspects. If the mixer is less efficient, it will less environmentally friendly than gasoline fuel.

20 years ago, propane was cheap and just as efficient a fuel as gasoline, and conversion made a lot of sense. It is much harder to justify now, on any basis.

#19 cookie

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Posted 18 September 2006 - 04:30 PM

If you recall the 1974 fuel crisis (some folks may not have been born) we could get propane a lot easier. We already used it in forklifts as it was much cleaner in a warehouse environment so we had some experience with the fuel.
I can't recall if it is CNG or propane they are using in taxis in Kiwi, (perhaps a Kiwi will comment), but the drivers reckoned it saved them a bundle.
I seem to recall we lost 10% mileage unless we raised compression. Saving the environment is a noble cause and this should give you a lighter footprint.

#20 LPGsuperchargedBrumby

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Posted 20 September 2006 - 01:37 AM

there are alot of taxis running LPG here in Kiwiland...and i've got a brumby/brat running dedicated LPG with no dramas

the Outbacks are running about 10 to 1 compression so LPG should run quite well in it as LPG tolerates high comp ratios very well (its roughly comparible to methenol in its comp ratio tolerance)

as for comment i saw early'r in the thread that LPG runs hot...it don't if it tuned right. LPG works reversed to petrol when it come to tuning rich or lean...as in the richer an LPG A/F ratio is the hotter it burns..the leaner it is the cooler it burns and LPG can be run rather lean before you notice a drop in power

with a well tuned system on a 10 to 1 motor i would be expecting about a 15% drop in MPG when running on LPG




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