Another gas/diesel question

Discussion in 'Lawn Mowing' started by bob, Jan 13, 2001.

  1. bob

    bob LawnSite Platinum Member
    from DE
    Posts: 4,254

    Doesn't torque dictate towing capabilities? I'm talking about JD 6 x 4 Gator engines. The 2 cylinder gas, 18hp, water cooled, 37.7 cu. in., 32.5 lbs-ft, has a towing capacity of 1200 lbs and a hauling capacity of 800lbs. The 3 cylinder diesel, 18hp, water cooled, 40.2 cu. in., 28.9 lbs-ft, has a towing capacity of 1400 lbs and hauling capacity of 1000 lbs. The gas engine has more torque than the diesel, but a lower payload. The 2 vehicles are built identical. Could the real question be a 2 cylinder vs. a 3 cylinder?
     
  2. Kent Lawns

    Kent Lawns LawnSite Senior Member
    from Midwest
    Posts: 870

    More ci diesel has LESS torque than a smaller gas engine?
    ~doesn't seem right.

    It has to do where the torque comes in: The diesel has more lower end torque for sure and that makes the real difference in towing.
     
  3. Eric ELM

    Eric ELM Husband, Father, Friend, Angel
    Posts: 4,831

    I could be wrong, but the torgue on a gas engine is measured at peak RPM. This torque rating drops big time as you drop the RPM's. The diesel is rated at any RPM and also runs at a lower RPM than a gas engine. In other words, a diesel is rated at constant torque and gas is at Peak Torque. If you lower the RPM's of a gas engine down to what a diesel is running, the gas engine would have less torque.

    An example is, I can engage double blades on my diesel JD 60" at an idle and it has an electric clutch. A gas engined 60" with double blades, it would kill the engine at an idle.
     
  4. Kent Lawns

    Kent Lawns LawnSite Senior Member
    from Midwest
    Posts: 870

    All engines have a torque and HP curve. If you look in the back of a Auto brochure where the engines are shown, you'll see them.
    The torque given is the maximum torque that engine produces.

    The flatter the torque line is, the better. The more torque at low RPM's the better.
     

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