New Toro w/Kubota Diesel ?????

Discussion in 'Lawn Mowing' started by Bull, Sep 18, 2005.

  1. Bull

    Bull LawnSite Senior Member
    from NC
    Messages: 308

    Does anyone have any information about a Toro ztr coming out soon with a 23 hp Kubota diesel? I would like to know as much as possible about this unit. Thanks
  2. South Florida Lawns

    South Florida Lawns LawnSite Platinum Member
    from usa
    Messages: 4,783

    they should know some specs and maybe have a brochure. The Toro website doesn't show this mower yet so you might have to wait a while.
  3. John Gamba

    John Gamba LawnSite Fanatic
    from ct
    Messages: 10,812

    It will probably be the XS.

  4. Bull

    Bull LawnSite Senior Member
    from NC
    Messages: 308

    My dealer said that he will have one in October. They always set up a booth at the fair and said that he will show it there. He does not have any info on it however at this time. It is supposed to be a three cylinder which my understanding is you can get the same amount of work out of a smaller horsepower engine if it is a diesel as with a larger gas engine.

    WREBELMACHINE LawnSite Bronze Member
    Messages: 1,089

    not enough power in my opinion!
  6. Texas Mower Parts

    Texas Mower Parts LawnSite Senior Member
    from Texas
    Messages: 472

    It's a 25 Kubota diesel, just like the new 06' Exmark.
  7. mowtech

    mowtech LawnSite Senior Member
    Messages: 252

    If you have an interest in moving to diesel engines from gas my word of advice is to demo the diesel machines before discounting the lack of horsepower. There are several reasons for this.

    First, diesel engines are generally rated more conservatively than gasoline engines. Instead of the horsepower look at and compare the engine’s displacement and you will see this.

    Second, diesel engines normally run lean, this means that whenever it is overloaded it can actually increase torque by adding additional fuel. A gasoline engine cannot. Because of this, diesel engines will out lug a gas engine allowing you the operator time to adjust to overloads while a gasoline engine will generally stall. This means you want more and more horsepower on your gas machines to overcome this stalling. Diesel engines can be sized closer to the required load because they are harder to stall.

    It will take at least a 30 horsepower gasoline engine to perform as well as a 23 horsepower diesel engine.
  8. fool32696

    fool32696 LawnSite Senior Member
    Messages: 993

    I agree with mowtec. Personally I'd take a 23hp diesel over a 30hp gasser any day of the week. The diesels run more efficiently (use less fuel). They are generally built much stronger (to handle the high compression ratio) and this leads to very long engine life. I've heard of Kubotas run into the 10000hr range in tractors. Also you can run off road diesel in them which I think runs about 50cents a gallon cheaper than on road diesel. Everyone here mowing with gassers is paying road taxes for cutting grass. As far as power goes, cutting grass is all about torque and that is what diesels do best. I would be willing to bet that the 23hp diesel makes more torque than the 30hp gas. It wouldn't surprise me if it made A LOT MORE TORQUE than the gas motor. The only bad things about a diesel are up front costs and heavy weight.
  9. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    Diesels make their torque at lower rpm. Horsepower is calculated as a function of torque and RPM withe RPM having an exponential effect on the HP rating.

    The long and short of this is that a 26HP diesel makes MORE torque than a 26HP gas engine.

    Have a great day,
  10. mowtech

    mowtech LawnSite Senior Member
    Messages: 252

    Careful, Horsepower = Torque*RPM/5252. This shows a linear relationship between rpm and hp, not exponential!

    When discussing diesel engines versus gas, make sure you don’t confuse the automotive application of engines to equipment such as mowers. In a mowing application the engines run at constant speed (you don’t push on the gas pedal for more power). Today on mowers, engine speeds between gas and diesel are comparable. At the same speed an engine with the same horsepower produces the same torque per the formula. On the other hand, a diesel that runs slower than a gasoline engine rated at the same horsepower would have to produce more torque to deliver the same horsepower, again per the formula. When we talk about torque in the fixed speed application; however, we generally are talking about “pull down torque”. A fixed speed engine slows down under load. This is because it can only produce so much horsepower so when it is asked to deliver more it can only slow down to compensate. Again this is per the formula. This is called droop. In a diesel as it droops under load the torque actually rises while a gasoline engine the torque remains flat. This torque rise will allow the diesel to lug longer and not stall. This is the performance advantage the diesel has in mowing applications and yes, the peak "pull down torque" under load of a 26 hp diesel is greater than a 26 hp gas engine and that greater diesel peak torque is at a lower speed.

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