Horse power versus revs

Discussion in 'Diesel Engines' started by Mik the stick, Dec 19, 2012.

  1. michael pierzga
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    michael pierzga Senior Member

    Perhaps. The local water supply has been cut for road works and since the holiday is upon us the bar will be closed till the new year.
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    FAST FRED Senior Member

    IF you can shake one loose from the engine mfg , or marinizer ,the chart you want is the fuel map.

    This looks like a series of clouds , a small one, then larger and larger around the others.

    This will show the rpm on one leg and the HP on the other.

    Inside each cloud is a specific fuel consumption at those rpm/load variations that fit in that cloud.

    Set up for the closest you can to the center (lowest fuel burn) cloud for cruise , don't worry about consumption at flank, most boats don't spend much time there.

    They are REALLY hard to obtain for specific engines, as folks would use them to select the "best" engine for their application.

    The fuel burn on the usual HP/RPM chart is for a theoretical math model propeller , NOT YOURS! (or anyone's)
  3. rubenova
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    rubenova Junior Member

    Question for Ad Hoc post #7, that's an interesting formula, what units are used?

    I'm familiar with (Torque in lb/ft * RPM)/5252=Horsepower
  4. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    If it doesn't matter who replies - the units have to be consistent. It means either all-SI, or all-British.
    So, either:

    1) SI: Torque (Nm), Power (W)
    2) Brit: Torque (lbf ft), Power (lbf ft / sec)

    If you need to get the HP value, it is calculated as follows:
    1) HP = Power[W] / 746
    2) HP = Power[lbf ft / sec] / 550


  5. Ad Hoc
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    Ad Hoc Naval Architect

    what he said :)
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