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Underdrive Pulleys

Discussion in 'GM Powertrain' started by Jarrett, Feb 18, 2010.

  1. Jarrett

    Jarrett Rockstar 100 Posts

    I've heard recently that underdrive pulleys supposedly significantly decrease the strain on your motor, and help make more horsepower and torque. Has anyone heard anything like this, could it actually be as good as it sounds? Any help would be appreciated.
  2. JennaBear

    JennaBear Rockstar 100 Posts

    They can free up some power but the gains aren't huge.
  3. Silverado Junkie

    Silverado Junkie Rockstar 4 Years 500 Posts

    JennaBear is right, the gains arent huge but they're there. But idd go for 'em because a littlebit here and there adds up after a while and then becomes a big overall improvement in your performance.
  4. corvetteforlife

    corvetteforlife New Member

    well i did all kinds of work to my 06 6.0L and i ran a dyno number at 625hp and 680 ft lbs. then all i did was put under drive pullys on and numbers came in a 636hp and 688 ft lbs. so ya they do help a bit
  5. JennaBear

    JennaBear Rockstar 100 Posts

    Was that on a load bearing dyno?
  6. Jacqson

    Jacqson Rockstar 100 Posts

    Underdrive pulleys will also make your alternator and any other belt driven items like the fan turn slower so at idle your probably going to get less amps from the alternator and less airflow through the rad. Mind you if you don't do a lot of idling or city driving in weather that puts a strain on your alt or rad then it's not really a big deal.

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