S
Scenic WonderRunner
Guest
Great Info..............!
Thanks.............RoundOut!
.
Thanks.............RoundOut!
.
Propane Conversions
- Thread starter articulate
- Start date
articulate
Expedition Leader
kcowyo said:
That's funny about gotpropane.com. I ride my bike right by that place on my way to work and didn't even realize it.
Anyway, about the availability of propane: "refillable anywhere" is probably more of a statement that means you can get it in most towns, certainly any city. Right, it's likely not found on three corners of every intersection like gasoline. But neither is diesel fuel. Except along the interstates. Propane sellers aren't always gas stations, so you have to get creative when on the hunt and - gasp! - may have to ask a local.
And someone mentioned something about propane getting fewer miles, which is not what I read (on the innernet
) I suspect that it depends --- fewer than what? How many MPGs do the beloved 80 series LC get when loaded down for a trip? Something like 10 mpg? Our Frontier pulls in 14-16 mpg loaded to GVW 5700 lbs. I wonder: where would propane fall under the same circumstances?
Westy
Adventurer
The problem with propane is not only finding a place that sells propane, but you have to remember that you need a service attendant to re-fill the tank. No 24hr fill-ups like gas stations/credit card machines, most propane fill ups must occur during 'regular' business hours. At some places, only certain attendants can re-fill tanks, etc...
articulate said:That's funny about gotpropane.com. I ride my bike right by that place on my way to work and didn't even realize it.
Anyway, about the availability of propane: "refillable anywhere" is probably more of a statement that means you can get it in most towns, certainly any city. Right, it's likely not found on three corners of every intersection like gasoline. But neither is diesel fuel. Except along the interstates. Propane sellers aren't always gas stations, so you have to get creative when on the hunt and - gasp! - may have to ask a local.
And someone mentioned something about propane getting fewer miles, which is not what I read (on the innernet
ntsqd
Heretic Car Camper
There is a book published by the SAE called "Alternative Fuels Guidebook"; Bechtold, ISBN 0-7680-0052-1
From it, energy equivalents to gasoline:
Propane:
72% of gasoline.
CNG:
Common storage pressures are 2400, 3000, and 3600 psi. For these pressures the equivalent amount of gasoline energy stored per unit volume is 22%, 27%, and 33%
LNG:
67% of gasoline.
Even though propane's Stoichometric Ratio is leaner than gasoline's (15.7:1 vs. 14.7:1), there will be a net loss in MPG due to the lower heat energy per unit volume.
Were you determined to run off home sourced Natural Gas you would need a re-fueling pump. Nat. Gas is supplied to homes at 11" of H2O or about 0.3974 PSI (roughly, te-he!)
Propane is a "dry" fuel. As such it really wants hardened valve seats on both the intakes and the exhaust valves. Upgraded valves are usually called for too.
One way to gain back some of the MPG loss is to increase the compression ratio. B/c of the higher 'octane' rating the engine will run with higher static compression ratios.
Unfortunately those higher static comp ratios can also increase the NOx emissions due to the higher combustion temperatures. Some research would be needed if this is a concern. I only know that it can happen, I don't know what the limits are.
From it, energy equivalents to gasoline:
Propane:
72% of gasoline.
CNG:
Common storage pressures are 2400, 3000, and 3600 psi. For these pressures the equivalent amount of gasoline energy stored per unit volume is 22%, 27%, and 33%
LNG:
67% of gasoline.
Even though propane's Stoichometric Ratio is leaner than gasoline's (15.7:1 vs. 14.7:1), there will be a net loss in MPG due to the lower heat energy per unit volume.
Were you determined to run off home sourced Natural Gas you would need a re-fueling pump. Nat. Gas is supplied to homes at 11" of H2O or about 0.3974 PSI (roughly, te-he!)
Propane is a "dry" fuel. As such it really wants hardened valve seats on both the intakes and the exhaust valves. Upgraded valves are usually called for too.
One way to gain back some of the MPG loss is to increase the compression ratio. B/c of the higher 'octane' rating the engine will run with higher static compression ratios.
Unfortunately those higher static comp ratios can also increase the NOx emissions due to the higher combustion temperatures. Some research would be needed if this is a concern. I only know that it can happen, I don't know what the limits are.
Last edited:
Martinjmpr
Wiffleball Batter
RE: MPG
If gas was $0.25/gallon, we wouldn't care about MPG (except maybe for long-range trips where we had to consider vehicle range and/or storage of extra fuel.) For most of us, the reason MPG is an issue is because worse MPG = more money spent on fuel and less money for other stuff.
IOW, though we may say "miles per gallon" as a shorthand for fuel economy, what we really mean is "cost per mile." A better MPG vehicle has lower cost-per-mile than a higher MPG vehicle. But, a vehicle with the same MPG that runs on less expensive fuel, also gives a better cost-per-mile.
So, how does the cost-per-mile of propane compare with gasoline? How much does propane cost at a commercial station?
As for the fuel issue, I think it would work but would require more extensive planning. You'd want to get a list of stations, and know their hours of operation. Also, is there any way that you could modify a propane vehicle to run on barbecue-grille-type propane tanks in an emergency? I could see that as being a good standby, if it works (don't know if it would be DOT approved, though.)
Of course, the best thing about converting to propane is that you'd make Hank Hill very happy, I tell ya what!
If gas was $0.25/gallon, we wouldn't care about MPG (except maybe for long-range trips where we had to consider vehicle range and/or storage of extra fuel.) For most of us, the reason MPG is an issue is because worse MPG = more money spent on fuel and less money for other stuff.
IOW, though we may say "miles per gallon" as a shorthand for fuel economy, what we really mean is "cost per mile." A better MPG vehicle has lower cost-per-mile than a higher MPG vehicle. But, a vehicle with the same MPG that runs on less expensive fuel, also gives a better cost-per-mile.
So, how does the cost-per-mile of propane compare with gasoline? How much does propane cost at a commercial station?
As for the fuel issue, I think it would work but would require more extensive planning. You'd want to get a list of stations, and know their hours of operation. Also, is there any way that you could modify a propane vehicle to run on barbecue-grille-type propane tanks in an emergency? I could see that as being a good standby, if it works (don't know if it would be DOT approved, though.)
Of course, the best thing about converting to propane is that you'd make Hank Hill very happy, I tell ya what!
Last edited:
ntsqd
Heretic Car Camper
As a point of reference, an acquaintance of mine up in B.C. has an Early Bronco (well, one part is EB, the rest he built) that runs on propane. He has done extensive trips down into the US south-west with the vehicle. It can be done.
At the time he built the truck Canada was actively encouraging folks to fuel their vehicles with propane and the price of fuel made it very attractive. Last time I talked to him the price isn't so attractive any more.
When I think MPG I'm really thinking in terms of range.
At the time he built the truck Canada was actively encouraging folks to fuel their vehicles with propane and the price of fuel made it very attractive. Last time I talked to him the price isn't so attractive any more.
When I think MPG I'm really thinking in terms of range.
Martinjmpr
Wiffleball Batter
Continuing these thoughts:
Just visited the following web site after a google search:
http://www.eia.doe.gov/emeu/steo/pub/contents.html
Projected propane cost was $2.28/gallon. Now, I don't know if that is propane motor fuel price, or whether that is some other price, and I don't know how closely that conforms to the "real world" price you'd pay if you had a propane vehicle, but with those caveats out of the way, let's assume arguendo that the cost of propane is $2.28/gallon and crunch the numbers:
Now, the other variable is how much of a drop in MPG you'd get from switching from gas to propane. I know the figure previously posted says that propane is 67% as efficient as gasoline. However, does this mean a propane vehicle will have 67% of the fuel economy? Maybe, maybe not, I'm not an engineer and I don't know if the efficiency and the MPG are one-to-one correlations. My guess is that they are not but I don't know.
But let's assume, arguendo again, that this is the case, i.e. that Propane vehicles have 67% of the economy of our gasoline vehicle.
So, here's how it breaks down: If the gasoline equipped vehicle gets 20 mpg (using a round number for easier conversion) then it will need 5 gallons to go 100 miles. At $2.75/gallon for regular gas (about what it is here in Denver) that works out to a total fuel expense of $13.75 to go 100 miles or 13.75 cents/mile.
If the propane vehicle is only 67% as efficient as the gas vehicle, then we can expect that it will only go 67 miles on 5 gallons of gas, which works out to 13.4 MPG. At 13.4 MPG the propane vehicle will require 7.46 gallons of propane to go the same 100 miles. 7.46 gallons x 2.28/gallon = $17.00 or 17 cents/mile, so at those prices the gasoline engine seems to be the better bargain.
But if the difference between the price of gas and the price of propane was more (either because of more expensive gas or less expensive propane), or if the efficiency of the propane engine was greater, it could make the propane engine more economically viable.
Just visited the following web site after a google search:
http://www.eia.doe.gov/emeu/steo/pub/contents.html
Projected propane cost was $2.28/gallon. Now, I don't know if that is propane motor fuel price, or whether that is some other price, and I don't know how closely that conforms to the "real world" price you'd pay if you had a propane vehicle, but with those caveats out of the way, let's assume arguendo that the cost of propane is $2.28/gallon and crunch the numbers:
Now, the other variable is how much of a drop in MPG you'd get from switching from gas to propane. I know the figure previously posted says that propane is 67% as efficient as gasoline. However, does this mean a propane vehicle will have 67% of the fuel economy? Maybe, maybe not, I'm not an engineer and I don't know if the efficiency and the MPG are one-to-one correlations. My guess is that they are not but I don't know.
But let's assume, arguendo again, that this is the case, i.e. that Propane vehicles have 67% of the economy of our gasoline vehicle.
So, here's how it breaks down: If the gasoline equipped vehicle gets 20 mpg (using a round number for easier conversion) then it will need 5 gallons to go 100 miles. At $2.75/gallon for regular gas (about what it is here in Denver) that works out to a total fuel expense of $13.75 to go 100 miles or 13.75 cents/mile.
If the propane vehicle is only 67% as efficient as the gas vehicle, then we can expect that it will only go 67 miles on 5 gallons of gas, which works out to 13.4 MPG. At 13.4 MPG the propane vehicle will require 7.46 gallons of propane to go the same 100 miles. 7.46 gallons x 2.28/gallon = $17.00 or 17 cents/mile, so at those prices the gasoline engine seems to be the better bargain.
But if the difference between the price of gas and the price of propane was more (either because of more expensive gas or less expensive propane), or if the efficiency of the propane engine was greater, it could make the propane engine more economically viable.
Martinjmpr
Wiffleball Batter
ntsqd said:
Neither have I. That was a total, worst-case-scenario WAG (Wild Ass Guess.)
At 10% loss the numbers would probably favor propane.
Martinjmpr
Wiffleball Batter
njtaco said:
I would assume (<---usual caveat applies) that propane sold as a motor fuel is properly taxed. However, propane from some other source (like an RV shop) would think is not taxed which could cause problems.
RoundOut
Explorer
Martinjmpr said:
With propane, there is no "marker" for road fuel vs. BBQ or heating fuel. In the case of diesel, there is a color difference added to the fuel. One is somewhat red and the other is somewhat green. I don't own a diesel engine of any kind, so I don't remember which is which. For propane, one would need a sight glass of some kind to check the color, since it vaporizes at atmospheric pressure.
However, if one is using diesel off-highway, one needn't pay the tax. One example I am aware of is the carnival industry. My sister used to (God, help her please!) ran with a carnival truck driver for a while. When they came to Houston, I went to see her while he was out purchasing fuel for their generators one afternoon. They don't have to pay the tax for that, but it is a HUGE fine if they get caught running it in their trucks.
Does anyone on here know if that applies to our domestic expeditions as well as the average farmer or carnival operator? If we could get off-highway diesel for expedition travel, that would save about $.385 in tax in the state of Texas.
Photog
Explorer
I did some study of properly prepared engines, for burning propane. It was a few years ago; so I am going by memory here.
Propane will operate in an engine designed to run on gasoline, just change the intake and fuel delivery system. But; a gasoline engine has been set up to burn gasoline, as efficiently as possible, not propane. So; if you convert a gas engine to propane, by changing only the fuel delivery and intake, you will get a reduction in fuel economy.
Theoretically, propane should burn more efficiently than gasoline, because it is already a vapor (dry), at temperatures normally found in the USA. Gasoline is a liquid, and must be converted to a vapor, or it will not burn. This transition to vapor from liquid, takes time and heat, in the combustion cycle. This reduces the efficiency of energy output from gasoline. This is not the case for propane. Said another way; you should be able to get more of the available energy from propane than you can from gasoline. You can actually extract more power per gallon from propane than from gasoline.
The engine must be set up to burn propane. The cam timing, lobe spread, valve lift, spark advance, compression ratio, etc., will all need to be changed, to properly burn propane. All the same things that have been done, to optimize an engine for gasoline, have to be redone for propane.
There are no ill effect to the engine; but there are many benefits. There is no sludge, the fuel does not wash the oil from the rings and cylinder walls, there are no residues, etc. All these problems with gasoline cause engine wear.
The last thing to consider. How much will it cost to PROPERLY convert a gas engine to propane? How many miles will you have to drive, to recover your expense, with better fuel economy, and cheaper fuel? If you are having your old gas-engine rebuilt anyway, then set it up for propane, and enjoy the savings.
Propane will operate in an engine designed to run on gasoline, just change the intake and fuel delivery system. But; a gasoline engine has been set up to burn gasoline, as efficiently as possible, not propane. So; if you convert a gas engine to propane, by changing only the fuel delivery and intake, you will get a reduction in fuel economy.
Theoretically, propane should burn more efficiently than gasoline, because it is already a vapor (dry), at temperatures normally found in the USA. Gasoline is a liquid, and must be converted to a vapor, or it will not burn. This transition to vapor from liquid, takes time and heat, in the combustion cycle. This reduces the efficiency of energy output from gasoline. This is not the case for propane. Said another way; you should be able to get more of the available energy from propane than you can from gasoline. You can actually extract more power per gallon from propane than from gasoline.
The engine must be set up to burn propane. The cam timing, lobe spread, valve lift, spark advance, compression ratio, etc., will all need to be changed, to properly burn propane. All the same things that have been done, to optimize an engine for gasoline, have to be redone for propane.
There are no ill effect to the engine; but there are many benefits. There is no sludge, the fuel does not wash the oil from the rings and cylinder walls, there are no residues, etc. All these problems with gasoline cause engine wear.
The last thing to consider. How much will it cost to PROPERLY convert a gas engine to propane? How many miles will you have to drive, to recover your expense, with better fuel economy, and cheaper fuel? If you are having your old gas-engine rebuilt anyway, then set it up for propane, and enjoy the savings.