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Helmholtz resonance airbox design?

  1. Jul 14, 2010 #1
    I have an airbox on a motorbike and want to find its frequency. I have two formulas:

    f = w / 2pi = 160 sqrt( 116.5 A / VL )
    f = ((343m/s) / 2PI) * SQRT( A / VL)

    A = Area of intake neck = 5.67cm^2 or 5.67x10^-4m^2
    V = Volume of airbox = 2500cc or 2.5x10^-3m^3
    L = Length of intake neck = 10cm or 0.1m

    I get the answers 26Hz for the first equation and 82Hz for the second. Which equation is correct?

    The first formula is from http://www.calsci.com/motorcycleinfo/Airboxes.html
    and the second is from wikipedia.
    Last edited: Jul 14, 2010
  2. jcsd
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