Why do 2 cylinder LP tractors have a higher fuel consumption?
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Thread: Why do 2 cylinder LP tractors have a higher fuel consumption?

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    green and red man's Avatar
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    Why do 2 cylinder LP tractors have a higher fuel consumption?

    I've heard those that own larger 6 cylinder JD LP tractors mention how thirsty the engines are on fuel compared to gasoline and diesel. That's one reason alone that I have been mainly interested in the smaller LP tractors. It wasn't until I started looking at the Nebraska tractor test data on 2 cylinder tractors that I noticed the difference in fuel burned per hour under load with LP tractors. Pretty interesting to also read about the 2 cylinder diesels holding a 27 year record for burning less fuel than other tractors. I can clearly understand the reason the diesels burn less than gas and LP. But am curious as to the technical reason/s behind a 2 cylinder LP engine burning more than gasoline. I've read all about the gas condensing to a liquid when under pressure. Also noticed that the Nebraska tests show that the 70 LP pulled more weight than the gasoline and all fuel models. Wasn't very far behind the diesel.

    Is the fact that LP gas has a higher octane rating the main reason for higher fuel consumption compared with the gasoline 2 cylinders? Just curious if there was more to it.

    When I used LP forklifts a lot, it did appear as though they used more fuel than others.

    Are there any LP experts on here?



    Last edited by green and red man; 10-31-2012 at 12:32 PM.

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    more or less speculation

    Propane weighs about four pounds per gallon gasoline and diesel about seven pounds per gallon. Does the pounds per horsepower hour match up closer than the gallons per horsepower hour.

    Propane without looking it up to be sure formula wise is C3H6. I guess this is the three carbon atoms double bonded kind of in a triangle and two hydrogen atoms hanging off each carbon. The liquid fuels have long carbon chains. Probably more energy in breaking the carbon bonds than in the carbon hydrogen bonds.

    Even the places that deliver propane (from the terminal to folks with 100 gallon or larger tanks) seem to be getting diesel trucks to replace the propane powered ones. My sample is not large enough to be conclusive though.

    fran
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    I always understood the basic differences in fuel consumption between the type of fuels was due to the BTUs contained in the fuel,, rough formula I seen used 8 gal a LP, 6 gal a gas, and 4 a diesel to do the same work,,, think that came from a mid 50s JD book.
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    Quote Originally Posted by js5020 View Post
    I always understood the basic differences in fuel consumption between the type of fuels was due to the BTUs contained in the fuel,, rough formula I seen used 8 gal a LP, 6 gal a gas, and 4 a diesel to do the same work,,, think that came from a mid 50s JD book.
    Quote Originally Posted by fran...k. View Post
    more or less speculation

    Propane weighs about four pounds per gallon gasoline and diesel about seven pounds per gallon. Does the pounds per horsepower hour match up closer than the gallons per horsepower hour.

    Propane without looking it up to be sure formula wise is C3H6. I guess this is the three carbon atoms double bonded kind of in a triangle and two hydrogen atoms hanging off each carbon. The liquid fuels have long carbon chains. Probably more energy in breaking the carbon bonds than in the carbon hydrogen bonds.

    Even the places that deliver propane (from the terminal to folks with 100 gallon or larger tanks) seem to be getting diesel trucks to replace the propane powered ones. My sample is not large enough to be conclusive though.

    fran
    Thank you both for that useful info. Makes sense to me. Thanks




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    It's the BTU's

    Going from memory but propane has around 90000 BTU/gallon, gasoline 124000 BTU/gallon, Diesel 135000 BTU/gallon. Ehtanol by the way has around 70000 BTU/gallon. Any mixture of gasoline and ethanol will result in more fuel consumption for the same amount of work.

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    rgd
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    Quote Originally Posted by edinmo View Post
    Going from memory but propane has around 90000 BTU/gallon, gasoline 124000 BTU/gallon, Diesel 135000 BTU/gallon. Ehtanol by the way has around 70000 BTU/gallon. Any mixture of gasoline and ethanol will result in more fuel consumption for the same amount of work.
    edinmo,I believe it may be btu/lb not gallon . Otherwise the numbers sound about right. I'm in the hvac biz and btu output for propane,natural gas, etc are usually stated in btu/lb. I know my 10 gallon propane tank will last 4 weeks heating my garage in most instances of moderate use
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