Announcement

Collapse
No announcement yet.

How to calculate percentage of total horsepower?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    How to calculate percentage of total horsepower?

    I’m new to this idea but I’ve recently viewed a post - I think by Smitty - saying to keep your engines below 60% (maybe it was 70%) total horsepower for maximum longevity of your engines. I originally thought that meant 60 or 70% of maximum rpms, however I don’t think that is correct. Would someone - please explain how to calculate percentage of horsepower? Thank you in advance.
    Todd, Lenore, Ryder and River
    1994 3888
    210 Hino’s with Hurth 630’s
    Cruise Inn

    #2
    Here is some info from the web.

    Mathematically, horsepower equals torque multiplied by rpm. H = T x rpm/5252, where H is horsepower, T is pound-feet, rpm is how fast the engine is spinning, and 5252 is a constant that makes the units jibe.

    So, all you have to do is find your engine manufacturer's torque vs rpm chart and use the above formula.

    Good luck!
    Retired, computer expert / executive
    Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
    Live in the Bay Area, CA, USA, boat in Turkey
    D-Marin @ Turgutreis in Bodrum/Turkey
    [email protected]
    [email protected]

    Comment


      #3
      Zentodd, not exactly sure what engine you have but according to this chart for the W04C-T1 th HP curve is clearly visible. 60% of the available 210HP is 126HP which equates to about 2200 rpm.

      https://www.marinepartssupply.com/me...vicemanual.pdf Click image for larger version  Name:	6587A56B-F3B3-4544-80E6-E49BF120BE63.png Views:	0 Size:	805.6 KB ID:	645929
      Jim Gandee
      1989 3888
      Hino 175's
      Fire Escape
      [email protected]
      Alamitos Bay, SoCal

      Comment


        #4
        You guys are awesome! Thank you both!
        Todd, Lenore, Ryder and River
        1994 3888
        210 Hino’s with Hurth 630’s
        Cruise Inn

        Comment


          #5
          Except you have no idea what torque is being produced when you're running at a given rpm on your boat. The torque vs. rpm chart just tells you the maximum torque the engine can produce at that rpm. So you can likely run at a higher rpm and still be under that magic 60% power number. Or depending on your boat, if you're running at 2200 rpm and plowing a huge wake, the engine fuel governor may be dumping the maximum fuel load into the engine to put out the max torque as it struggles to maintain that rpm and it could actually be a worse operating point than going faster and getting on plane at a higher rpm but lower torque.
          Brad
          Lake Union, Seattle
          1987 Bayliner 4550 "Ark Angel"
          Hino EH700T / MG-502 / Cummins Onan 7kw
          Seattle Yacht Club

          Comment


            #6
            Purdue, I agree with your assessment. However, pending any other published data specific to the vessel in question I think the Hino performance curve is about as close as one could get.
            Jim Gandee
            1989 3888
            Hino 175's
            Fire Escape
            [email protected]
            Alamitos Bay, SoCal

            Comment

            Working...
            X