Dyno results Underdrive pulleys

Discussion in '2005 - 2009 Specific Tech' started by JTGrant, Jan 6, 2007.

  1. Anyone have just results from a dyon with the only change being underdrive pulleys? I am about moded out as far as bolts-ons are concerned. I would like to add a cam but the prices are to high right now. Thanks
  2. no dyno sheet, but the engine revs MUCH faster now. very noticable gain on my car. even my wife noticed the difference the first time she got in. :)
  3. Have you experienced any negative effects?
  4. nothing yet...
  5. how many miles to you have on your car since the install?
  6. i didnt look at the mileage, but i think only about 1000. give the thread a few days and others will chime in with more miles on the clock.
  7. Get the pulleys!!! I was worried about the negative effect on the water pump, but since I am running the 4.10s that turns her a little faster to compensate.

    +1 on the faster reving.
  8. Any change in coolant temp or alternator output that you notice?
  9. Do you need to tune for the pullies? I had to on my 05 f150.
  10. Why would you need a tune for pullies?
  11. They said they had to bump up the timing and also it helped had idle with the a/c running:shrug: Thats what they told me when I had it done.
  12. No timing adjustment needed. Dyno's have been from around 5-10hp and around 10lbs of tourqe if you google it and hunt for a while. I noticed a differance when I had Steeda's installed about 6 months ago. MM & FF's most recent magazine comes with a DVD on a 05 GT piece by piece install and dyno per part. They got 10hp on the dyno with BBK UDPs.
  13. I don't think your mechanic knew what he was talking about.
  14. Besides, U/D pulleys don't increase HP ? they free it up by slowing down your belt driven accessories such as your water pump and A/C which have nothing to do with the computer's stock tuning files... therefore no computer re-flashing is necessary.
  15. I have had underdrive pullies on my 88 Vette for over 100,000 miles with no negative effect. They will be going on my GT in the near future.

    There is absolutely NO tuning necessary when changing to underdrive pullies.
  16. :shrug: maybe its different for f150's cause the guy is a pretty big online programer on f150online.com:shrug:
  17. A bump in idle speed is generally required to maintain alternator charging levels. Side effects of going with underdrive pulleys include:

    Reduced A/C output in low speed driving
    Reduced power steering assist in low speed driving
    Reduced alternator charging at idle

    Bumping the idle speed UP will only reduce these side-effects. I've used the Steedas on my 4.6 2V for about 20,000 miles and eventually just went back to the stock pulleys.
  18. I did experience some negatives with them on a 95 Mustang GT. They caused my headlights to brown at idle and significantly contrbiuted to an overheating problem that I had when stuck in traffic. I realize that our cars are completely different than that Mustang, but can definitely see why someone would ask the question before purchasing & installing this mod.
  19. Marine One:

    You brought up an excellent point. On my 00 Vic (4.6 2V V8), the headlights did dim at idle and got worse when I had more accessories on at the time (HVAC blower, Air Conditioning, stereo, and turn signals).

    I'm never going to try underdrives again in any vehicle, but that is just me. :SNSign:
  20. I share your viewpoint.