I don't remember seeing the topic here and my search didn't reveal anything.  I'm interested in opinions on converting a tow vehicle to run on natural gas.  I have two Ford F-350, one a 6.0 diesel and one an 86 460 gasoline engine. 

Why would you want to use NG?  The range of such a vehicle is very low since the fuel even if liquified or compressed isn't energy dense.  Fueling stations are far and few...

Well, Hosspuller, that's part of my question.  The reason for considering it is the economy of the fuel.  I think there is a considerable savings on operation cost, but don't know that for certain, of course - I saw 30 percent at current rates.  Natural gas should continue to get cheaper and diesel and gasoline will continue to get higher.  The one place I read about the conversion was a 7.1 Ford and there was an automatic switch back to diesel when the natural gas tank was empty.

Maybe it's not worth investigating - I've just been hearing more about it recently and remember when it was popular a few years ago.  I know of a big city in India that changed all of its buses and commercial transportation.

I think the basic problem of NG is physical ...  Here's a table of energy density

http://en.wikipedia.org/wiki/Energy_density

Compared to diesel, LNG is about a third less energy per gallon than diesel.  Go to Compressed NG and the reduction is 2/3 less.  NG is best used in a fixed location or as in your example a fixed route that the fuel supply stays within.

If the fracking opponents win, NG will go back to expensive.

Wish I had a gas well in my back yard ... 

Here in Utah, they are pushing for more Natural Gas filling station. The state in partnership with Questar Natural Gas installed some 15 station last year, bringing the state wide total to 39 righ now. One filling station is about 10 blocks from my home. They play some games in measurements, But it seems the common quote is for a "Gas Equivalent Gallon". Meaning you are buying the same amount of energy as a gallon of gas. I don't know what that equals in gallons or lbs of natural gas. But supposedly the same number of btu's.  And that is currently selling for $1.48.  Which is less than half of what gas cust and 35% of what diesel fuel now cost. So it is definitely more cost effective to use vs driving on gas.  IF you can get the conversion done for a reasonible price. And it has stayed constant almost the entire year. No up and downs in pricing like we see at the gas pump.

Because the filling station is close by. I have several neighbors that have purchased Natural Gas vehicles from several manufactures. A Ford F150, another has Honda or Toyota  that came from the factory already set up to run on NG. It cost a couple of thousand more to buy the factory vehicle that way,But they are saving big time every mile they drive. For them commuting into Salt Lake City each day is very cost effective.

There are conversion for older diesel that allow the diesel to run on 2:1 up to 4:1 ratio of Natural Gas to Diesel. These makes your cost per mile go down. You still need to have some diesel fuel in combustion chamber to start the combustion process. Since diesel engines don't have a spark plug to ignite the gas. But with the conversions you can run extremely lean, especially once you are up to highway cruise speed. Unfortunately, I have not seen any of these conversions for the newer diesel that came out after 2007.  Seems the 2007 emissions requirements made modifying the newer engines impossible.

The biggest problem with CNG is the tank. They need to be designed to hold 3000psi. Which makes for an expensive tank. Most conversions usually put in smaller tanks, Both because of the cost and the space required. Which means the converted vehicle has a smaller range than a similar vehicle with a normal gas tank. Instead of filling up your tnak once a week, you are filling up 3 times a week. So you have to factor in something for what your time is worth to be involved in more frequent fill ups.

The benefit of the diesel conversion was that you still had to have diesel in your tank and if you ran out of CNG that you running at 4:1, your truck just automatically reverted to running 100% diesel.

Mr Truck did a review on his conversion several years ago. I suspect it is still in the other forum if you did a search for it.  It was in his review forum.

His Review

http://www.horsetrailerworld.com/forum/thread-view.asp?threadid=11486&posts=1

I appreciate all of the information.  The links are very helpful, too. 

It seems that mostly people talk of converting diesel engines.  Gasoline engines can be converted, too, can't they?

I had two things in mind when I posted this; one for a tow vehicle and one as a possible replacement SUV for my driving car.  I want rugged 4wd that can handle seriously bad 4wd roads and wanted improved mileage on that. My little old 4Runner is just not quite rugged enough and I was thinking of making a change.  I'd take a little more risk on that than on my truck! 

Great information.  Thanks!

My neighbor that drives the F150 works for Questar Gas. So as a gas employee, I'm not surprised to see him drive a natural gas vehicle.  He refuels at work, so cost is on the company's dime and since he is in the parking lot daily, I suspect that it's no inconvience, it's not like he's looking for refilling station.

The tanks for CNG conversion are the real cost. Tanks that are certified to hold 3600 psi of pressure are not cheap and they are somewhat bulky. Since most vehicle retain their factory fuel tanks, Any CNG tanks are usually an add on and it often takes a truck or larger SUV to have room to hold the tanks.  The gas vehicles that are converted at the factory, usually are not bi-fuel and so the primary gas tanks are removed. Leaving the vehicle totally dependant on CNG

There is a farm in Tennessee that we often buy from that has 400,000+ miles on their truck. They are West Wind Farms (on web and Facebook). You could ask them about theirs. They drive from East Tennessee to West Tennesee, and down into Georgia every single week and pull a trailer making deliveries.

From their FB picture: Our 2005 Compressed Natural Gas GMC Sierra delivery vehicle just rolled over 400,000 miles yesterday & is still in perfect health. Pulled a loaded trailer over 70% of those miles. My work horse is as dependable as they come!

I noticed that they have a tank in the bed of the truck...

Just a thought.

West Wind Farms and local CNG...

How about a brand new truck ??

http://articles.philly.com/2012-11-25/news/35348913_1_cng-vehicles-cng-option-civic-gx

Fracking has a lot of positives for this country...

This is all such great information.  I appreciate all of the valuable information, opinions and ideas.

Well, the second one is a bit severe!  The first one isn't clear to me.  What were they putting in the tank with the nozzle?  Why was the trunk open?