The Stovebolt Site Forums The Shop Area Engine Shop Gas to Propane- is it worth it?

To all us truck diehards,
Saw an older post where propane system was added so the truck could owner could swith from gas to propane or propane back to gas. With the cost of gas at $4 plus who has any views on this as an alternative, and how easy it it to set up?

Eric

Propane was used in the 50's and 60's because it was dirt cheap and burned so much cleaner. However, it really was low power. I remember a fleet who ran Intl R190's with RD450 engines converted some of them. They took the propane off because no one would drive the converted ones for lack of power. If a 450 cu in engine has lo power with LP, what would one expect from a smaller engine. Up until the 80's or so propane distributors used LP powered delivery trucks. Now they are almost all use diesel. Must be a reason.

If you raise the compression of the engine to take advantage of it, propane can make plenty of power, but in an engine designed for gasoline it is going to be down on power.

Its probably worth it right now, I saw propane at $2.40 a gallon this weekend and it takes 1.35 gallons of propane to equal one gallon of gas in energy content.

First, take a look at the cost of conversion.

Now, figure as to the reduction in fuel economy, and calculate how much you MIGHT save per 1000 miles under the very best possible ideal conditions using the highest propane figures.

Now, calculate how many hundred thousand miles you will have to drive just to break even.

Having lived with a factory equiped dual fuel vehicle (gasoline/propane) and its associated issues (difficult cold starts, difficult hot starts, lack of power, constant fill-ups, hot stalling under heavy load, etc.), I honestly would prefer a bicycle REGARDLESS OF COST!

Our factory equiped system would do 9.5~10.5 MPG on gasoline; less than 4 MPG on propane. Absolutely impossible to obtain 100 miles on a 40 gallon propane tank!!!

But others may have differing opinions.

Jon.

Ditto, Jon! I ran the maintenance shop for a sand & gravel company that ran a lot of their equipment on propane. The fuel conversion was a pretty primitive affair that used a liquid-to-vapor converter, and ran the vapor through a conventional carburetor housing. Displacing enough air to get sufficient fuel vapor through the venturi was responsible for the power loss.

Propane is 104 octane, so an engine can be boosted to 11.5:1 compression or higher, but that kills the dual-fuel capability. If someone could design a system to inject liquid propane at the intake port, a lot of the power loss could be avoided, but the cooling effect of -70 degree fuel evaporation would turn the intake manifold into a block of ice. Besides- - - -it's still a byproduct of petroleum refining, so where's the cost savings with $100.00+/barrel oil?
Jerry

Another issue that comes to mind: how much propane can you put in an empty tank??

One who knew nothing about propane would assume that if one has a 40 gallon tank, one could fill it with 40 gallons of propane. Right? NO, WRONG!!

How much propane may be placed in the tank is a function of the ambient temperature. This you find out when you have the tank filled with propane.

This may explain my previous post where I mentioned that we got less than 4 MPH on propane, but could not get 100 miles from a 40 gallon tank. You cannot put 40 gallons of propane in a 40 gallon tank!!!

Jon.

I have heard of propane injected into diesel engines as a power boost. This doesn't sound right to me but someone told me that trasctor pullers do it. Does anyone know anything about this? I've wanted to get straight on this for a good while.

Dave - propane with diesels is a fairly common topic on some bus forums - here's more than you wanted to know about it

Bill

I used to maintain a fleet of trucks that they converted to propane in spite of my advise not too. These college grads sitting in there plush offices know more then a dumb mechanic. The systems were unreliable. We had a lot of valve jobs from valve seat recession. They were clumsy to fuel & with the short range they had to be towed back to the warehouse to fill up. A dual system would solve that problem but then it is more complex.

i'm to young to know a whole lot about it but i know back in the 50's and 60's alot of farm tractors ran on propane, you can easily tell which ones were propane cause of the large round tank buldge out of the hood never knew anyone that had one but one year when i was doing FFA corn drive one farmers place we stopped at had a Minneapolis Moline LP tractor and me being one who is interested in old tractors/cars/trucks i looked real close at it (from a distance) and he had it setup with a fuel line that when to a LP tank that you would use for a house he just had the tractor parked on a cement slab and it was hooked up to a corn dryer (stationary use) i thought it was a pretty cool idea

Nate

Another consider is fuel tax. Every state is different but when lp is delivered into motor vehicle it becomes subject to motor fuel tax. I think right now the Federal government first collects .20 and then allows a .50 tax credit but it is a lot of paper work. I have been a fuel distributor and interstate trucker for over 40 years and if it were not part of my business, I wouldn't mess with the paper work. And the propane tanks have to be so large that you can't hide them.

A friend of mine has a finished '55 Chevy pickup that runs on propane. I almost never see it anywhere but at his house. I see his unfinished gas powered '57 panel all over.

In addition to all the above comments which which I also agree, there is also the safety factor to consider. Propane is heavier than air, which means that if it leaks, it will pool in low areas and is an extreme hazard. The system needs to be installed by someone certified to do the installation ( if you want insurance ) and needs to be inspected regularly.
Bob