Question about Vance and Hines quiet baffles

Discussion in 'Sportster Models' started by Elias, Oct 18, 2008.

  1. Elias

    Elias New Member

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    First of all i want to say a big hello to all.
    I'm a new member from Greece and found this forum very interesting.
    I have a Sporster XL883 2008 Model and replaced the sock exhausts with Vance & Hines Straightshots HS Slip Ons.
    The problem is that they are too loud!
    So i ordered a pair of Vance & Hines quiet baffles.
    Could you somebody tell me the difference in noise (in Db) before and after insatlling the baffles?
    Your help would be very helpfull.
    Thanks in advance.
    Elias
     
  2. Elias

    Elias New Member

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    Thanks for your reply!
    How many Db are the pipes without the quiet baffles?
    The bike's licence state that with stock exhaust pipes it will be 96Db,which is legal here.
     
  3. Elias

    Elias New Member

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    Hi,did you checked them?
     
  4. docsledge

    docsledge Active Member

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    Elias,
    Don't know if you've got everything resolved yet, but here is something.
    Hobbit is on the right trail. Measure sound pressure levels at 1 meter from source to get accurate reading. Probably should be more toward the back instead of just to the side. Done at idle (warm) and maybe 2500rpm.
    Another site had one guy who measured V&H big shots without baffles (104db from 6ft), with stock baffles (98db at 6ft), and quiet baffles (92db at 6ft).
    This was done on Vulcan Nomad, probably the 1500cc model.
    I used to work in underwater sound propagation (AntiSubMarine Warfare Acoustic Analyst) while flying with the Navy. All that means is we hunted Soviet Nuke Submarines for a living.
    Underwater 3db increase or decrease means a doubling or halving in sound level.
    In the air use 4db up or down for the doubling or halving.
    As Hobbit stated, sound levels are not linear (wish they were), but are logarithmic on a scale of 3db or 4db. For our bikes sake, I would prefer to use the air reading.
    I just put a set of big shots on my dyna and I'll probably be getting the quite ones. Seems a bit loud to me. Maybe I'll get used to them. Also, putting in the quiet baffles is supposed to help the low end and mid range torque some. Little more back pressure.
    Now all I have to do is figure out how to remove the old (from new set of pipes) baffles.
    good luck,
    doc
     
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  5. Elias

    Elias New Member

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    Hello Doc!
    Thanks for your reply.It was very helpfull.
     
  6. docsledge

    docsledge Active Member

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    Elias,
    No problem and glad to use what little knowledge I've got.
    doc
     
  7. phoenix

    phoenix New Member

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    Just read this & very helpful thanks.I have just done actually the same well nearly I will fit the new Q-baffles on weds but will also be wrapping the pipes black for the old skool look.
    cheers fella