1st Gen R53 Cooper S Question concerning underdrive pulleys

Discussion in '1st Generation: 2002–06 R50, R53 & 2004–08 R52' started by oldvet53, Feb 5, 2013.

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  1. oldvet53

    oldvet53 New Member

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    #1 oldvet53, Feb 5, 2013
    I'm getting ready to do a 15% WMW Supercharger underdrive pulley and a PRW Fluid Crankshaft Damper Pulley that I also got from WMW and did some checking and it is a 8.7% underdrive pulley. My question is what should I expect from this combanation, will there be low output charging problems with the alternator being underdriven at slow speeds like around town?:confused5:
     
  2. Crashton

    Crashton Club Coordinator

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    #2 Crashton, Feb 5, 2013
    No experience, but yes the alternator is going to spin slower. Your supercharger is going to spin faster. You got a 15% pulley to be safe over a 17%. Now you are going to be somewhere near the same as the 78%.

    If it was Me I'd call Way & have him swap you a stock sized PWR damper for the undersized one. You have plenty of time to make the exchange before your pulley install.
     
  3. ScottinBend

    ScottinBend Space Cowboy
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    #3 ScottinBend, Feb 5, 2013
    ^+1

    Get the proper sized crank puley.
     
  4. jiminni

    jiminni Well-Known Member

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    #4 jiminni, Feb 5, 2013
    8.7% underdrive crank pulley? You sure about that? Never heard of such a thing. Most people use 2% OVERDRIVE crank pulleys :Thumbsup:
     
  5. Crashton

    Crashton Club Coordinator

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    #5 Crashton, Feb 5, 2013
  6. Dave.0

    Dave.0 Helix & RMW Powered
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    #6 Dave.0, Feb 5, 2013
    I would only run the stock size.
     
  7. jiminni

    jiminni Well-Known Member

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    #7 jiminni, Feb 5, 2013
  8. jiminni

    jiminni Well-Known Member

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    #8 jiminni, Feb 5, 2013
    And why is that?
     
  9. Crashton

    Crashton Club Coordinator

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    #9 Crashton, Feb 6, 2013
    For me it would be turning the supercharger too fast. I went with a 15% pulley, because I intended to use my MINI on the track occasionally. From what I had read it was recommended to go with a 15% for that use. The 17% was said to be fine for street use, but not so fine on the track.

    If I remember correctly the OP said in another post that he wanted a 15%, because it was safe. His MINI is high mileage so I agree with his thoughts.
    Going with an under-drive crank pulley will turn the Supercharger faster than just the 15% with a stock sized crank pulley would.
     
  10. oldvet53

    oldvet53 New Member

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    #10 oldvet53, Feb 6, 2013
    I talked to Way and he confirmed that the Crank Damper pulley was the stock size, I had looked on the PRW site and it said it was a underdrive pulley. Thus the confusion so I'm good. I should have just talked to Way first.
     
  11. Crashton

    Crashton Club Coordinator

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    #11 Crashton, Feb 6, 2013
    I understand the confusion since both are listed. Good to know Way sent you the one you wanted. :Thumbsup:
     
  12. BlwnAway

    BlwnAway Well-Known Member

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    #12 BlwnAway, Feb 6, 2013
    Glad it got sorted, I couldn't see a reason for it either, wonder if it was designed for a different veh. & just happens to fit our engines so they cross advertise it that way.

    Under Size Crank Pulley = Slower Accessories
    Under Size Accessories Pulley = Faster Accessories
     
  13. Kavs

    Kavs New Member

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    #13 Kavs, May 23, 2013
    If you tell me diameter of crank pulley I can suggest to you exact pulley size which will match to your mods and wishes. A big range of pulleys is from -11 up to -20%.
     

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