Difference between peak and continuous HP?

Discussion in 'Motorized Bicycle General Discussion' started by virginian, Jun 15, 2011.

  1. virginian

    virginian New Member

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    I have a Tanaka PF3300 that says it has a peak horse power of 1.6 HP and a continuous horse power of 1.1 HP. Which number is most relevant?

    In an explanation that I read, the continuous HP is the power that can be generated when the motor is running at constant speed, and peak HP is what it can generate when it is being forced to slow down (like brake HP).

    So, if I am running at constant speed, the most I can get out of the engine is 1.1 HP? If I am going up a hill and slowing down, I can get the peak HP - 1.6 HP - but just for an instant when the engine iRPM is at the point of peak HP? Is that correct? Does that make sense?
     
    #1 virginian, Jun 15, 2011
    Last edited: Jun 15, 2011
  2. decoherence

    decoherence New Member

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    hmm. i like this question.

    does it give the HP @ different RPMs?
    like 1.1HP @ X.RPM
    1.6HP @ N.RPM

    being my thing is electronics, max wattage is crap.
    in all actuality RMS can be a crap spec.
    "BOSS" makes amps they rate @ 1KW. that could possibly make that once & never again.
    then "ORION" makes an amp they rate @ 1 watt but could shatter windows.
     
  3. virginian

    virginian New Member

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    The datasheet that Tanaka provides has a curve showing maximum HP of 1.6 HP at 8500 rpm.

    Other rpms have lower HP. For example, at 4000 rpm HP = 0.9, at 5500 rpm HP = 1.3, and at 9000 rpm HP =1.5.
     
  4. "the prussian" Shop Dogs

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    A true horsepower minute is a unit of work done over time. Not an absolute.
    There are a lot of factors that play a role . All elec. Motors with out electronics to "soft start" achive full toruqe when power is engaged and in theroy that is the peak H.P. Once engaged and turning there is a slight lag and that power output could be concidered cont. H.P. Most of the bike motors I've delt with have some kind of soft start setup.
    Please remember that these numbers come from people who want to sell motors so they tend to bumb the number up to look more powerful. But I belive you on the right track in thinking about it in a hill climb . On the level your runing at 1.1 and in trans to the climb it runs at 1.6 for extra power ,but only for a few sec.
    And of corse it all depends on how the motor power is reg. Via electronics or reostat or direct wireing?
    Sorry it's not a simple answer ,and I'm sure there are those who will diagree with me .
    I got my education in the service not in an enginering school ,so maybe someone with letters after there name can explaine it better.
    Hope this helped some...
     
  5. decoherence

    decoherence New Member

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    yea, it is hard to say unless you see a graph.
    draw yourself a little graph & plot those two points. being that they gave a HP @ what RPM, I would think they are closer to actual that just giving a stated HP.
     
  6. virginian

    virginian New Member

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    Well, I studied this question by looking at various websites. I am not sure that I got it right, but this is what they seem to say.

    The peak or maximum is stated for the rpm that gives the highest horsepower. The graph for my engine (Tanaka 32cc) gives peak HP at 8500 rpm. With my gearing 8500 rpm is 34 mph, which is a little faster than my actual peak speed on the flat.

    If I look at the performance graph, peak torque is at 5000 rpm (20 mph with my gearing). The horsepower at 5000 rpm is given as 1.1 HP. Perhaps the "continuous HP" means the HP at peak torque.
     

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