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under drive pully yes or no

This is a discussion on under drive pully yes or no within the External Engine forums, part of the LSx Technical Help Section category; i have a 1999 ss a4 with american raceing headers to slp lm1, slp lid ,jet pcm,smooth bellow, port and ...

  1. #1
    Member SSMOKEshow's Avatar
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    Feb 2008
    in the world

    1999 Camaro SS

    under drive pully yes or no

    i have a 1999 ss a4 with american raceing headers to slp lm1, slp lid ,jet pcm,smooth bellow, port and pollished tb.umi lower control arms and panhard bar. should i get on under drive pully and what brand

  2. #2
    I would say wait till you get a cam, if your ever going to get a cam. becasue since you have to take it off anyway when putting in a cam but therwise I think its too much of a hassel just to replace the pulley.

  3. #3
    Member hoss 2000 z-28's Avatar
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    Apr 2006
    Jeffersonville, Indiana

    Monterey Maroon Metalic
    2000 Z28

    If you are in between big projects (H/C vs FI) or you have some money burning a hole in your pocket, it sure wouldn't hurt. It's certainly not a "must do" mod though. I agree with Rapter though, if you plan to do a cam it would be best to do it then.

    I bought a Powerbond pulley (they make the SLP pulley) and got a Goodyear Gatorback serp. belt. Been using it for the better part of a year with no ill effect. The only negative effect is that my amp meter at idle is barely in the red during idle. Once the car is moving again it quickly jumps back into the safe operating zone. I have never had my battery fail.

    Not sure if you have read up on UDPs or not but this may help...

    A UDP is no power adder. There is no seat of the pants benefit that I could feel but physics says the smaller pulley is lighter and less massive than the stock one so it revs up faster and reduces parasitic power loss. So on paper it makes your car a little more efficient.

    The only concern in using an underdrive pulley is if you have a large electrical demand on your car (amps, subs, tv's, etc.), the smaller pulley won't turn your alternator as fast and your battery could go dead in a hurry. But they do offer alternator pulleys that offset the underdrive crank pulley so your charging won't be affected compared to stock.

    TexasSpeed offers packages for UDP, Alt pulley, new crank bolt, and belt for a reasonable price. You can also shop around and have parts delivered separately but it's nice to get everything all at once.

  4. #4
    2 SS's are better than 1 Jays00ss's Avatar
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    Jun 2007
    Lathrop, Missouri

    NBM / Silver
    00 SS / 71 SS Elcamino

    underdrive pulley takes maybe 45 minutes to put on. With the proper tools that is. Its a great mod to do and really gets you up to your powerband a lot faster. Good For a tenth or 2 at the track. I gained 4 rwhp with mine and it pushed me over the 400 hp mark.

    As far as brand goes. I got a Powerbond and they are excellant quality as well as price. They are the company that supplies them to SLP but without the SLP price.
    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

  5. #5
    Moderator Firebirdjones's Avatar
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    May 2006
    I used an underdrive pulley on mine for about 6 months. Ended up taking it off just recently.

    Not a real big fan of them. I did back to back comparisons with it. It yielded absolutely nothing at the track for me,,,,no ET,,,no MPH improvements at all. I noticed nothing as far as the engine reving up faster as some claim.

    I noticed for the most part that voltage was low if the rpms were below 1,000,,,,,so idling caused the headlights/dash lights to dim. Even kicking the idle up a pinch really didn't help matters.

    But,,,the last straw for me was the fact that it ran the water pump so slow that the engine would get up to temp,,,fans would kick on and stay on while in traffic or parked. The only time I could get the fans to kick off would be if I clicked up to neutral and held the motor at 1,500 rpms,,,,to circulate the water fast enough,,,the fans would then shut down in about 30 seconds.
    But as long as I idled,,,the fans would run continuously due to a slow moving water pump. And it was only 85 degrees outside. I would hate to think what it would do in hot desert conditions....which I will be seeing soon,,,(another reason why it came off).

    This was annoying enough for me, coupled with the fact that it yielded no ET or MPH gain so it came back off to sell it.

    Some people like them and some may even find improvements. I found it was good for a door stop and the worst $300 I spent on the car.

    I personally would save the money and put it towards some tuning software,,,,,or better yet,,,another good best bang for the buck with your auto would be a nice converter.

  6. #6
    Member Empatho's Avatar
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    Jan 2007
    San Diego

    02 Z28

    I have one on my z28 and it improved my throtle response, and like said before if you plan on getting a cam then wait until then.

  7. #7
    JUISSED Midnight02's Avatar
    Join Date
    Feb 2007

    Navy Blue Metallic
    2002 Camaro SS

    Like the others have said, it is worth doing if you're planning a cam swap or need a few extra hp to meet a personal goal. I can't really speak to true dyno gains, because mine was installed during my cam swap.

    If you decide to get a pulley, be sure to get one of the models with the higher retaining walls....this will help keep your belts from slipping off. I also went with the Powerbond/SLP pulley and have been pleased with it thus far.
    2002 Camaro SS M6, 2.5 PRC 5.3L heads, TFS 228/230 cam, FAST 92, bolt ons + a 10 lb bottle in the back.

    1989 Corvette L98, A4, Full bolt ons, etc.

  8. #8
    Join Date
    Apr 2006
    Chowchilla CA

    2001 Z28

    An underdrive works best with an electric water pump. These pumps run at a constant speed. However, they do have longevity issues.

  9. #9
    15 sec. Oh yeah, its fast UTVols98's Avatar
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    Apr 2007
    Forest Lake, MN

    2000 Z28

    Yes, get one when you get a cam. It'll let you build up the RPM's much faster, especially when you need to get into your powerband. Made a difference with my cam.

  10. #10
    Member Fran D's Avatar
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    Aug 2005
    Washington Crossing, PA
    I've been running an ASP pulley for about 60K miles and 4 years. I've never had a heating or charging issue with it. As mentioned, it takes less than an hour to swap one.

    Is it a must do? No. It's in the category of every little bit helps. Aside from the track gains (~1 MPH), I also threw it on for whatever MPG benefit there may be to reducing parasitic losses.

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