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Underdrive Crank/Alternator Pulley Question

This is a discussion on Underdrive Crank/Alternator Pulley Question within the External Engine forums, part of the LSx Technical Help Section category; If I opt to install an underdrive pulley on my LS1 2000 Z28 will I see an increase in RWHP? ...

  1. #1
    Member 89LX's Avatar
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    Underdrive Crank/Alternator Pulley Question

    If I opt to install an underdrive pulley on my LS1 2000 Z28 will I see an increase in RWHP? Is it woth the $$$ and which do you consider the best. Thanks

  2. #2
    Senior Member mrr23's Avatar
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    you will see about 8-10 rwhp out of an under drive pulley set up. is it worth the money?? up to you. do you want to get all the hp you can? then, yes. is $100/hp a good buy? not really.

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    Member 89LX's Avatar
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    Good point on the $$$ to HP ratio. I have a lid, smooth bellows, K&N filter and Hooker CB. I was attempting to add a little extra without going internal or changing up my exhaust. Thanks for the reply.

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    Member ProwlerZ's Avatar
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    Maybe I'm off, but isn't an underdrive pulley only like $200? And if that is the case, you'd be talking about $20/hp. Not the greatest deal, but once you're maxed on bolt-ons and too poor for power adders or cam/heads, it doesn't look too bad.

    Btw, there's still a list of things to do before you hit serious money. Headers (which aren't cheap) should be a priority, ported TB with coolant bypass, gears, and a tune will all help, some a lot more than others.
    Last edited by ProwlerZ; 06-09-2006 at 05:20 PM.
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    Slow'er'Ass Mr. Luos's Avatar
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    If you gain 8-10 RWHP for a $200 pulley...you aren't doing bad in my opinion.

    I did the ASP underdrive pulley (crank only) on my stroker. No idea what gains it gave me. Didn't have a before/after dyno.
    I do know I had enough power to require a solid tensioner with that pulley though.
    2008 Trailblazer SS
    Yank PTB3600, Kooks 1 7/8" LT's, 4" intake, E-fans, Magnaflow, Sonnax kit, tranny cooler, tune.
    Lowered, HID's, tinted.

    1999 Pontiac Trans Am WS.6 #1747 SOLD
    531.1 RWHP 481.3 FT/Pounds all motor.

  6. #6
    Senior Member mrr23's Avatar
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    Quote Originally Posted by ProwlerZ
    Maybe I'm off, but isn't an underdrive pulley only like $200? And if that is the case, you'd be talking about $20/hp. Not the greatest deal, but once you're maxed on bolt-ons and too poor for power adders or cam/heads, it doesn't look too bad.

    Btw, there's still a list of things to do before you hit serious money. Headers (which aren't cheap) should be a priority, ported TB with coolant bypass, gears, and a tune will all help, some a lot more than others.

    i was using a for instance on the dollar/hp thing.

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    and that's pretty much the ratio for headers.
    $600/~20HP = $30/hp

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    Senior Member ninobrn99's Avatar
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    even if you dont notice a big gain in hp, you will notice faster revs...that helps out alot. You should only see 8-10 yes, but again, with these motors its not about what one mod does, but what the combination does

  9. #9
    ILL SKEET IN YUR EYE
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    I HEARD GOODTHINGS ABOUT THE SLP PILLEY 25% UD CUZ IT HAS EXTRA MATERIAL ON IT SO THE BELT WONT THROW. IM GONNA GET THIS ONE SOON. IVE HEARD MANY TIMES OF OTHERS WITH LS1 UD PULLEYS LOSING BELTS. F THAT ESPECIALLY IF YOUR OUT OF TOWN WHEN IT GOES. THAT WOULD SUCK

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    Senior Member Street Lethal's Avatar
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    Quote Originally Posted by breakparts
    I HEARD GOODTHINGS ABOUT THE SLP PILLEY 25% UD CUZ IT HAS EXTRA MATERIAL ON IT SO THE BELT WONT THROW. IM GONNA GET THIS ONE SOON.
    SLP makes a great pulley!

  11. #11
    Senior Member MadSeason's Avatar
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    I use a march pulley and saw a 2mpg increase in fuel economy on the HW

  12. #12
    Member 89LX's Avatar
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    SLP Underdrive Pulley

    Ordered a SLP F-Body Underdrive Pulley (P/N SLP100221) from http://www.ls1speed.com/ for $213.16 and no S&H. Best buy I could find and a savings compared to other sites. Found the Gates belts on Amazon.com for $53.97 to the door.

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