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.

  1. oldvet53

    oldvet53 New Member

    Oct 21, 2012
    277
    79
    0
    Disabled/Retired
    N.E. Arkansas
    Ratings:
    +79 / 0 / -0
    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

    Jun 4, 2009
    19,069
    9,616
    113
    Retired old fart
    Hooterville Ohio USA
    Ratings:
    +10,886 / 2 / -0
    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
    Supporting Member

    May 4, 2009
    8,726
    2,501
    113
    Bend, OR USA
    Ratings:
    +2,600 / 0 / -0
    ^+1

    Get the proper sized crank puley.
     
  4. jiminni

    jiminni Well-Known Member

    May 7, 2009
    1,592
    260
    83
    Ca.
    Ratings:
    +260 / 0 / -0
    8.7% underdrive crank pulley? You sure about that? Never heard of such a thing. Most people use 2% OVERDRIVE crank pulleys :Thumbsup:
     
  5. Dave.0

    Dave.0 Helix & RMW Powered
    Lifetime Supporter

    May 4, 2009
    25,023
    13,489
    113
    Burbs of Philly, PA
    Ratings:
    +14,635 / 10 / -4
    I would only run the stock size.
     
  6. jiminni

    jiminni Well-Known Member

    May 7, 2009
    1,592
    260
    83
    Ca.
    Ratings:
    +260 / 0 / -0
  7. jiminni

    jiminni Well-Known Member

    May 7, 2009
    1,592
    260
    83
    Ca.
    Ratings:
    +260 / 0 / -0
    And why is that?
     
  8. Crashton

    Crashton Club Coordinator

    Jun 4, 2009
    19,069
    9,616
    113
    Retired old fart
    Hooterville Ohio USA
    Ratings:
    +10,886 / 2 / -0
    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.
     
  9. oldvet53

    oldvet53 New Member

    Oct 21, 2012
    277
    79
    0
    Disabled/Retired
    N.E. Arkansas
    Ratings:
    +79 / 0 / -0
    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.
     
  10. Crashton

    Crashton Club Coordinator

    Jun 4, 2009
    19,069
    9,616
    113
    Retired old fart
    Hooterville Ohio USA
    Ratings:
    +10,886 / 2 / -0
    I understand the confusion since both are listed. Good to know Way sent you the one you wanted. :Thumbsup:
     
  11. BlwnAway

    BlwnAway Well-Known Member

    Nov 24, 2011
    474
    290
    63
    Ratings:
    +314 / 0 / -0
    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
     
  12. Kavs

    Kavs New Member

    Nov 22, 2011
    13
    0
    0
    Ratings:
    +0 / 0 / -0
    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%.
     

Share This Page