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60" vs 72" power requirements

Discussion in 'Lawn Mowing' started by tacoma200, Sep 4, 2006.

  1. tacoma200

    tacoma200 LawnSite Fanatic
    Messages: 5,426

    How much more hp does a 72" deck require to mow at the same speed as the same mower with a 60" cut? If I had a 27 hp 60 inch Scag Turf Tiger for instance how much more hp would I need if it were a 72" to cut at the same speed through heavy grass?
  2. rodfather

    rodfather LawnSite Fanatic
    Messages: 9,501

    probably around 5
  3. tomo

    tomo LawnSite Senior Member
    Messages: 660

    hello,thick wet grass
    60 inch 30hp
    72 inch35hp ## Look at all the out front diesels on market all with hp i mentioned
    Even the new breeds of z turn toro 28hp 1.1ltr
    kubota 28hp 1.1ltr
    Iskei 33hp 1.5ltr
    john deere 31hp 1.3ltr
    Diesel is always prefered when heavy cutting. Diesel will always hold your speed better than gas engine in heavy conditions. tomo

    REALSLOW LawnSite Senior Member
    from FLORIDA
    Messages: 668

    I calcualted how much power it would take to make a 72 go like a 60 and I came up with 35 to work like a 60 27 but what the hell do I know I was just figuring how much more grass had to be cut and pushed out the deck and it was alot!
  5. 2manymowers

    2manymowers LawnSite Member
    Messages: 116

    Why is this true? Do diesels produce more torque for the same horsepower engine?
  6. Imow4u2

    Imow4u2 LawnSite Senior Member
    Messages: 377

    Yes sir, they do!

    REALSLOW LawnSite Senior Member
    from FLORIDA
    Messages: 668

    On the average a deisel will produce 1/3 more torque than gas because it does not turn many RPM to make it's HP that is also why they are low HP because they do not turn many RPM.
  8. 2manymowers

    2manymowers LawnSite Member
    Messages: 116

    The problem is very few manufacturers post the torque numbers for their engines. I think my 32 hp Generac gas engine(72" Dixie Chopper Extreme Mowchine) is plenty of power for short or thin grass, but for heavy lush or tall grass it is very underpowered. I now wish I had invested the extra money in the 50 hp turbo diesel that was available in the 2005 models.
  9. kc2006

    kc2006 LawnSite Silver Member
    Messages: 2,443

    Like I said in another post, my 28efi is plenty for my 60" exmark but on a hustler 60" i'd want at least the 30hp kohler (maybe more power, I don't know what kinda power the 30's really have). For a 72" exmark, the 35hp briggs would be plenty, but I'd go diesel for fuel effeciency. For a 72" hustler, all they have is the 30hp and diesel, I wouldn't even think of a 30 on a 72" hustler, that would be underpowered I'd think, i'd go diesel for sure.
  10. olderthandirt

    olderthandirt LawnSite Platinum Member
    from here
    Messages: 4,899

    I don't believe it takes that much more HP. The reason is that most mowers have so much more hp now than just a few yrs ago. The latest fad in mowers is who will put the biggest engine on. I had a Steiner with a 72" deck and a 20 hp onan gas and I had a Kabota with a 60" deck and 21 hp diesel. The Steiner out cut the bota in speed and quality in side by side mowing in long thick grass. This can be attributed to many things including design. But to your question once the blades are spinning it would be hard to bog them down with an extra ft. of deck, thats only 4" per blade. I'm talking about the average diffence between engines in the average heavy grass.
    It was not many yrs ago that a 16 hp on a 54" deck garden tractor was considered a BIG engine

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