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Old 03-06-2012, 03:13 PM   #1
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Converting a Classic to CNG

What do you think about converting one of these moho to CNG? The average price for a Gallon Gas Equivalent of CNG is 78 cents in this country. The conversion on a Chevy 454 is not that hard and there seems to be ample room under my 350LE to install a CNG tank. I would keep the gas tank and have a switch to toggle between fuels. I could fill it up at home if I installed a cng filling station/compressor. I know cng has less power but Iím not sure if I would notice it all that much. Any thoughts?

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Old 03-06-2012, 03:29 PM   #2
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Very interesting idea. I was just wondering the same thing after reading about converting gas gensets to propane.

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Old 03-06-2012, 03:39 PM   #3
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I had a conversion to propane on an 80's Chevy pickup. There was substantially less power than with gasoline. Also had issues with the throttle plate beneath the carburetor burning out.

I would also think re-fueling while on the road would be difficult with CNG.

Not sure how my experience with propane compares to CNG, but would like to follow this thread to hear other's experiences.
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Old 03-06-2012, 05:54 PM   #4
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Where will you fill it up and how much will it cost?

I found a web site, CNG CNG stations and Prices for the US, Canada and Europe showing locations and recent prices at public CNG stations. For example, there are only four in the state of Ohio--two in Columbus--and recent prices are shown around $2.00 per GGE (gallon of gasoline equivalent).

Increasing number of local delivery companies are switching to CNG for their vehicles, but they maintain their own private filling stations.

Rather than convert vehicles to run on compressed natural gas and build thousands of CNG filling stations to service them, it would seem to me to make more sense to build a few large plants to convert natural gas to synthetic gasoline and diesel fuel and then distribute that through the existing distribution channels. The technology to do this is not new; Nazi Germany fueled its war machine in WW II with fuels produced by the Fischer-Tropsch process, and the South African company, SASOL, has several successful coal-to-liquid and gas-to-liquid plants.

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Old 03-07-2012, 11:53 AM   #5
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Standard conversion over here in England is propane. Nashfuel do the kits. IMPCO is the way to go.
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Old 03-07-2012, 12:27 PM   #6
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I've driven and owned both propane and CNG powered vehicles. Both have less power when operating on the alternative fuel. The CNG was significantly under powered compared to the propane one. The excessive heat was also an issue requiring more frequent oil changes.
The biggest difference between them is that CNG is stored as a vapor and propane is stored as a liquid. This meant that the CNG powered vehicle had a much shorter range than the propane powered unit requiring frequent fill ups. I was lucky that I had several convienient locations to fill from but I wouldn't consider it for any long distance driving.
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Old 03-07-2012, 07:13 PM   #7
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Originally Posted by SteelyDan View Post
Very interesting idea. I was just wondering the same thing after reading about converting gas gensets to propane.
If you have an Onan, the propane conversion may still be available. Ours runs clean and mean on propane.
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Old 03-08-2012, 02:35 PM   #8
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Sure - propane gives you a little less power, but then the 454 is capable of dealing with this for most classics. I know several people who have run the 454 with the proper IMPCO conversion for many many years without problem; the upside is that is broadly halves fuel costs in Europe
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Old 03-09-2012, 11:24 PM   #9
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CNG Conversion

Interesting idea, but not feasible for a motorhome due to the high cost of conversation, CNG tanks and limited range. To come close to your gasoline engine range, you would likely need four large capacity CNG tanks - which cost approximately $6,000+ each let alone the cost of conversation. Fueling off a home system, at the capacities needed (3600psi) is also not feasible at it would take a few days to fuel. CNG works well for fleets that travel many miles each day and return to a central yard where they can be fueled by a slow-fill (overnight) or fast-fill compressor plant. Compared to gasoline and diesel, natural gas is very inexpensive as a vehicle fuel, provided you have the right kind of vehicles, maintenance capabilities and a properly sized fueling plant.
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Old 06-23-2012, 11:53 PM   #10
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$6k+ for CNG tanks??? Maybe if you are talking a large size & the most expensive type 4 fully wrapped composite liner nonmetal tanks. Type 2 or Type 1 are much much cheaper, 3600psi and DOT approved. The only downside is they're some what heavier. I thought i remember reading type-1s have a longer useable lifespan too, but don't quote me on that.
I don't know what your space/weight constraints are ..but you could probably accomplish your goal using a bank of 3-5 type-1 tanks. Here's a place I found with a quick around I've seen them actually cheaper than this place. CNG Tanks, CNG Cylinders and Natural Gas Storage Tanks

Since you are keeping your gasoline tank/system intact as a bi-fuel setup, you can switch over to gasoline when the CNG is exhausted, this actually enhances your total range.
Also we are talking about an RV here....soooo you won't be home most of your trip. It seems like a moot point to mention anything about slow filling "home" fueling apparatus.
Public and company fill stations are FAST-fill and take about the same time as filling with gasoline. If you look at the link mention previously CNG Western routes 40, 60, 70 & north route 95 seems like you could find enough stations. If you go due south maybe not.

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