Underdrive Pulley 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.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
i got an A4 and i didn't order the alt pulley. my idle is slightly higher from a cam tune though and i have no power hungry electrical accs either. i will let you know my results bc my UD is still on the table in the shop. ha ha.
I have no power hungry stuff either, I even removed the A/C. The car is not a DD and see's track only. I have HPT so I can idle it down a little. How about cooling? Does a underdrive pulley affect cooling?
Your water pump is going to spin slower with the under drives. They are what, a 10% or 15% under drive? I couldn't say if that is going to reduce the flow so much that the system can't recover. On your signature I don't see any reference to 160 degree thermostat or tuning that would lower the cooling fan settings. You say track only but do you trailer to the track? If you do trailer it, I wouldn't worry about it. If you drive to the track...45 minutes of stop and go with a 100 degree day, hard to say.
Its a 25% underdrive pulley. Yes I have a 160 thermostat and my fans are set lower. Theres not enough room for me to list everything on my sign. Thanks for your input.
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I've used an SLP 25% underdrive pulley on my '06 GTO for over 36k without one issue. No alternator pulley change. It's an A4, has a 160 t-stat, stock water pump, fans set to come on at lower temp, sees about 75 passes at the track a year.
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Joined: Jun 2008
Posts: 2,585
Likes: 3
From: Edmond, OK
i have an A4 and plan on getting both the ASP underdrive crank and underdrive alt. pulleys. i removed my a/c and powersteering so my question is should i have any charging probs with both the underdrive crank and alt pulleys? considering the only accessory im turning besides the alt is the waterpump
