Results 1 to 19 of 19

Underdrive Pulley Question

This is a discussion on Underdrive Pulley Question within the External Engine forums, part of the LSx Technical Help Section category; For the guys who are running underdrive pulleys, Are you running an overdrive pulley on your Alternator? Do you have ...

  1. #1
    JMAC Racing WS6ICK's Avatar
    Join Date
    Aug 2005
    Location
    Kentucky
    Posts
    535

    2000 Trans Am WS6 LS6
    2006 GTO LS2

    Question Underdrive Pulley Question

    For the guys who are running underdrive pulleys, Are you running an overdrive pulley on your Alternator? Do you have any charging issues? Its going on my 2000 Trans Am, WS6, A4.
    2010 Camaro
    2006 GTO, LS2, 1 of 475
    2009 Chevy Silverado


  2. #2
    Member
    Join Date
    Aug 2005
    Location
    Northern Virginia
    Age
    54
    Posts
    464

    BLACK
    2000 Camaro SS

    Running an ASP underdrive on my 2000 SS M6, stock alt. pulley. Idle speed set to 650, no charging issues.

  3. #3
    JMAC Racing WS6ICK's Avatar
    Join Date
    Aug 2005
    Location
    Kentucky
    Posts
    535

    2000 Trans Am WS6 LS6
    2006 GTO LS2

    Some say that I should run a overdrive pulley on my alternator because its an A4.

  4. #4
    Member
    Join Date
    Aug 2005
    Location
    Northern Virginia
    Age
    54
    Posts
    464

    BLACK
    2000 Camaro SS

    I would try it without it first since the alternator overdrive pulley partially negates the benefit of the underdrive pulley. If your system discharges too much at idle and you spend a lot of time at idle, then get it later. This of course assumes that an overdrive pulley does not require a different sized belt. I don't know about that one.

  5. #5
    Member NaviDyn's Avatar
    Join Date
    Dec 2008
    Location
    St Louis
    Age
    44
    Posts
    115

    Tan
    2002 GMC Yukon

    I ran underdrive pulleys on an old 5.0. I didn't change the alternator pulley for obvious reasons. But even with the much smaller crank pulley, it charged fine. On a motorcraft.

  6. #6
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    I had the underdrive pulley on my 02 SS. I didn't care for it much and it didn't yield me any performance that I could measure so it came off.

    Mine is also an automatic. I never did install an overdrive alternator pulley, I felt that it had the opposite affect of what I was trying to accomplish with underdriving everything. I did set the idle speed up a tad to help but I still had dimming lights at night when idling,,,and if the A/C was on it was worse. That was more of a bother to me, didn't have any dead battery issues. What I did have that I could not tolerate was the fact that it turned the water pump so slow that while idling around town the fans would constantly run and struggle to bring down the engine temp. Especially if I were running the A/C... Even with fans only set on 185 degrees they wouldn't shut down unless I was moving at a constant speed with higher engine rpms,,,idling was just too slow for the pump to cool the motor. Once the stock crank pulley was reinstalled,,,,like magic the fans would cycle as they should and cooled the engine no problem. This was while living in Ohio. Now that I'm in Arizona I could only imagine that problem being even worse.
    Last edited by Firebirdjones; 12-15-2008 at 12:47 PM.

  7. #7
    Member cuzimoto's Avatar
    Join Date
    Feb 2008
    Location
    Newport Beach
    Posts
    407

    Black
    99 Formula

    have had the ASP underdrive for 6 years, no charging problems at all.

  8. #8
    Junior Member wildbanshee's Avatar
    Join Date
    Apr 2008
    Location
    florida
    Posts
    68

    pewter
    2000 camaro

    slp underdrive...no problems..actually i would say it made a bigger difference on my car than slp air lid...

  9. #9
    Junior Member wildbanshee's Avatar
    Join Date
    Apr 2008
    Location
    florida
    Posts
    68

    pewter
    2000 camaro

    if that means anything...

  10. #10
    Junior Member
    Join Date
    Mar 2008
    Location
    Pittsburgh
    Posts
    78

    Black
    2001 Camaro Z28

    Quote Originally Posted by WS6ICK View Post
    Some say that I should run a overdrive pulley on my alternator because its an A4.
    i have an asp on my car and its an a4 and i dont have any problems - it goes to the "begining of the red" when @ idle butother than that nothing. I dont have the alt. overdrive either. I heard that should be used for things requiring more amp draw like a bigger stereo etc.



    hope this helps,

    Bill

  11. #11
    Member Bouvers's Avatar
    Join Date
    May 2006
    Location
    Canada
    Age
    31
    Posts
    857

    Blue 1997 Trans Am(Sold)
    Pewter 2001 Trans Am Vert

    Plenty of people have ran it without the Alt. overdrive pulley and have been fine but if you're running more accessories then you should.


    my beef is on my dd my alt. was screwed and it was charging 25% less then it should... which is exactly what and underdrive pulley will do... so kind of leads me to go with an alt. overdrive pulley... just my .02$

  12. #12
    2 SS's are better than 1 Jays00ss's Avatar
    Join Date
    Jun 2007
    Location
    Lathrop, Missouri
    Posts
    2,479

    NBM / Silver
    00 SS / 71 SS Elcamino

    No chargeing issues with my powerbond. 3 rwhp increase but you can really feel the difference in how fast you reach your powerband. Very good mod and I would highly recommend it.
    2000 SS Camaro Heads, Large cam, Fast 90, 9"w/430's and locker, yada yada yada... you get the picture

    1971 SS ElCamino 402 Big Block 550HP

    2006 Silverado 2500HD 496 cubic inches of pure muscle

  13. #13
    Senior Member karpetcm's Avatar
    Join Date
    Oct 2008
    Location
    Tujunga, CA
    Posts
    1,646

    White
    01 Camaro 6speed

    Which is the cheapest pulley and do they all work just the same ?
    Last edited by karpetcm; 12-20-2008 at 05:38 PM.

  14. #14
    Senior Member SS02's Avatar
    Join Date
    Dec 2006
    Location
    ...
    Posts
    2,819

    None
    ...

    I have pulley set with the Alt over pulley, it might have
    been in my head... Yet I swear it made a diff at pedal!

    Not probs at all.

    I had that dynod with other mods so not sure on the HP increase?

  15. #15
    Member slpdablueZ28's Avatar
    Join Date
    Sep 2008
    Location
    brooklyn
    Posts
    403

    blue
    2002 Camaro Z28

    what do overdrive and underdrive pulleys do exactly and wats the difference between them?

  16. #16
    Member
    Join Date
    Aug 2005
    Location
    Northern Virginia
    Age
    54
    Posts
    464

    BLACK
    2000 Camaro SS

    Quote Originally Posted by slpdablueZ28 View Post
    what do overdrive and underdrive pulleys do exactly and wats the difference between them?
    The main "underdrive" pulley replaces the stock pulley that is attached to the end of the crankshaft. It has a smaller diameter than stock, which means for any given engine rpm, it causes the belt to travel less distance, which in turn causes all the belt-driven accessories (alternator, water pump, power steering pump) to turn slower, thus soaking up a lower percentage of the engine's power.

  17. #17
    Member Justin93's Avatar
    Join Date
    Oct 2007
    Location
    CANFIELD, OHIO
    Age
    31
    Posts
    654

    PEWETER METALIC
    2002 CAMARO Z-28 M-6

    I have the powerbond 25% UD Pulley and have zero alternator issues. It revs faster. Also I have a red top optima under the hood so i've noticed no drop in voltage
    Last edited by Justin93; 12-21-2008 at 12:10 PM.

  18. #18
    Member slpdablueZ28's Avatar
    Join Date
    Sep 2008
    Location
    brooklyn
    Posts
    403

    blue
    2002 Camaro Z28

    Quote Originally Posted by mbrownin View Post
    The main "underdrive" pulley replaces the stock pulley that is attached to the end of the crankshaft. It has a smaller diameter than stock, which means for any given engine rpm, it causes the belt to travel less distance, which in turn causes all the belt-driven accessories (alternator, water pump, power steering pump) to turn slower, thus soaking up a lower percentage of the engine's power.
    ah ok thanks

  19. #19
    JMAC Racing WS6ICK's Avatar
    Join Date
    Aug 2005
    Location
    Kentucky
    Posts
    535

    2000 Trans Am WS6 LS6
    2006 GTO LS2

    ok. I will wait to see what it does when I install the UD pulley before buying a OD pulley for the alt. Thanks.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Underdrive pulley install question
    By KDZRGROWN in forum External Engine
    Replies: 4
    Last Post: 10-19-2008, 12:24 PM
  2. Underdrive Pulley-Does It Need OD Alternator Pulley
    By Eddie 70 in forum External Engine
    Replies: 16
    Last Post: 10-01-2007, 09:23 AM
  3. Underdrive Crank/Alternator Pulley Question
    By 89LX in forum External Engine
    Replies: 11
    Last Post: 06-20-2006, 08:07 AM
  4. Underdrive Crank Pulley Question
    By 89LX in forum External Engine
    Replies: 2
    Last Post: 06-10-2006, 09:52 AM
  5. underdrive pulley install question
    By tx77015ls1 in forum General Help
    Replies: 4
    Last Post: 05-09-2006, 09:06 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •