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Discussion in 'Technical and Troubleshooting Torque' started by boxman, Jan 26, 2009.

  1. Can somebody please explain to me what the hell this is?
    Have heard and read about it for ages, and I can have never cared about what it is. It's time I found out.


  2. It's a phrase that typically applies to any motor that has a "peaky" power delivery, meaning one that feels like it isn't making a whole lot of power until the revs get within a certain range (band) and then the motor starts making a lot more power. Rev it too high though and the power drops off again fairly quickly.

    ie. there is a "band" or "range" of engine speeds for which the engine quite markedly makes a good deal more power than at other engine speeds.

    Most typically this applies to 2-stroke engines as the harmonic waves that occur in the exhaust system become ideal for extracting exhaust gases and sucking in fresh air-fuel mixture. Above and below this ideal harmonic range the engine doesn't "breath" as well, and so lacks power.

    Some 4-stroke engines do exhibit a form of "power banding", but this is more due to poor design than any real legitimate reason for why it should be so.
  3. If you look at the dyno graph of an engine, you will see that it is a line of engine power vs rpm.

    the gearbox on any vehicle means that the engine covers a certain rpm range when you shift.

    the powerband is the greatest "area under the curve" within the certain rpm range that a gearbox allows.

    max power need not be near redline.
  4. Thanks- can sleep easy tonight
  5. You can get fully adjustable powerbands here.
  6. Not going to disagree, but thats only half the point.

    The 2-smoker's exhaust shape will setup up a bow wave which will push back against the exiting gas and squeeze it back into the cylinder. This enables the air-fuel mix to get squashed back into the engine and produce slightly more power. Since this happens at a narrow band in the rev range, this is typically called the powerband.

    Wiki watch the animation - it explains it.
  7. Hahaha.. that site is a crack up :LOL:
  8. That is totally piss funny

    :p :p :p :p :p :p :p :p :p :p :p :p