building a new truck, pondering propane/gasoline
 

Hello everyone, my name is Lee, im a truck addict, apparently. i've got something like 12 trucks currently ( hard to keep track) but the one involved with this conversation is a 1992 Ford F250. the truck is a clean southern truck, a reg. cab longbox 2wd, with a blown up 351W and an automatic ... so its currently getting torn down for a fresh engine, suspension work (getting a few inches lower) and some other helpful mods.

I plan on driving this truck for years when its finished, as in for the rest of my years that i'm driving. i stack on plenty of miles, and love to travel the country. it was brought up to me by some friends to look into running both propane (for my daily driving duties, etc) and running gasoline as a backup ( for when im in the middle of nowhere and can only find a gas pump)

Is this a feasable option? what would all be involved? is it as cost effective as it sounds??

Welcom to the DIESEL forum...............

You posted in the wrong forum for the help your looking for. I'm moving it to the proper forum....

thank you sir ... much appriciated ....

As long as you are willing to give up the load space for the tank, its not that complicated. The real question I have is how much does propane cost in your area? Here, it makes no sense at all due to the price. Natural gas is cheap here, but converting a truck for that is complex and expensive. Propane systems, as I understand them, just put a vaporizer in front of the throttle body and it flows on demand while the gasoline injection is switched off.

The one thing you cant have with dual fuel is raise the compression to take advantage of the higher antiknock index of 105. Also a gallon of propane only has 74% the energy content of gasoline. Keep that in mind with cost calculations, expected mpg, range and tank size.

Curious where to read about the natural gas conversion issues? e.g. does it have the anti-knock advantage as well, & is the energy conversion similar to lp? What accounts for the cost & complexity - is it simply the higher pressures in the storage tanks and their cost?

i decided, due to the cost and complexity, that it would not be worth the trouble for the minimal savings in fuel costs.

I guess you could add water/methanol injection to a dual use setup if you
wanted to up the compression...

Yes, Methane (CH4) is 130 Octane (research and motor). Energy density is even lower, 25% of gasoline by volume, due to it being a compressed gas, not a liquid. You are right, the cost and complexity is due to extremely high pressures, up to 3600psi. Also, for a given range, the tanks have to be much bigger.

Since you should have multiport EFI on your 92 F250, the simplest conversion (both LPG and CNG) is to use an injection conversion - all are dual fuel. These work much better than mixer-based conversions and cost about the same. Although it is true that propane has about 74% of the energy of gasoline on a volume-basis, a propane injection conversion typically gets better than than 80% of the truck's gasoline fuel economy. Since CNG is advertised in terms of gasoline gallon equivalent (GGE), a CNG conversion should get about the same miles per GGE as the gasoline mpg.

Instead of giving up load space in the bed, there are tanks available to mount underneath the bed in place of the spare tire. You can either mount a manifolded LPG tank (eg 26.2 LPG gallons - 2 x13" tanks, 32" long) or pair of 6.7 GGE (15.2" dia x 35.4" L) 3600 psi cylinders.

Some gas utilities have CNG compressors available to rent. In Ontario, Enbridge has the Fuelmaker C3 available for $90/month and this CNG costs less than $2/GGE, all in. Public CNG stations are usually cheaper but aren't often on your way home. If you use less than 13 gallons/day of gasoline, this type of CNG setup might make economic sense.

If you have a bulk propane supplier nearby, I would check to see what kind of deal they can offer you on a motor fuel account (minimum 1000 gallons/year). This propane consumption is about equivalent to 1350 gallon/year of gasoline. You lock in an annual price during the summer when the propane market is low.

If you want to use your truck to travel the country, a propane conversion makes more sense as propane is more widely available. The parts (underhood kit, tanks, etc) for propane conversion will run $2000-$2500.

decided to drag this thread out of hibernation

The 92 F250 i spoke of in the first post is still not finished. funny how life has a way of getting in the way like that. plans changed, its getting bigger, better things. and maybe propane, still havent decided with that one.

so right now im working with my 1993 F350 2wd. big old 4 door longbox, 351W, 5 speed. Ive been shopping around for propane kits for it. What im wondering is who has seen or done propane tank mounting that mounts inside the drivers frame rail, where the side mount tank used to live? it would be an ideal spot, i would still be able to retain my rear fuel tank, and i would still have full bed use. Anyone have any info on that?

Otherwise, what would be the largest tank i could fit in the bed that would stay in front of the wheel wells and fit underneath my roll top tonneau cover?

I have a propane tank on the frame rail where the original gasoline tank was, 95 litres. And another tank in the back, replacing the rear gas tank, that's 110 litres. I've had it like that for 28 years. It's been a great set-up for me running on propane only.

hi oldblue ... nice to see another local guy (i am in new west).
i have a similar set up, except mine holds a total of 160 litres.
i would never mount a propane tank in the bed, simply because i use my truck as a truck.