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Downside to an underdrive pulley?

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Old Aug 4, 2008 | 11:45 PM
  #21  
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I ordered a powerbond pulley kit from Byunspeed today, $215 for pulley, two belts and the GM crank bolt shipped. They are a ls1 tech sponsor. The powerbond/slp's have the higher ridges so you are unlikely to throw a belt. Some a4 guys have charging issues, some don't. I didn't buy the overdrive alt pulley, I was going to wait and see if I experienced charging issues.
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Old Aug 5, 2008 | 12:49 AM
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Originally Posted by gymratt
I ordered a powerbond pulley kit from Byunspeed today, $215 for pulley, two belts and the GM crank bolt shipped. They are a ls1 tech sponsor. The powerbond/slp's have the higher ridges so you are unlikely to throw a belt. Some a4 guys have charging issues, some don't. I didn't buy the overdrive alt pulley, I was going to wait and see if I experienced charging issues.
you're probably going to end up getting that pulley later on because they made that alt pulley specially for a4s.

my pulley is an asp 25% udp and I race it, daily drive it, do burnouts every now and then, hit the track and run the **** out of it, and I've never had 1 problem out of mine. From my research the asp one gives the most power. I believe it weighs the least of all the underdrive pulleys too. I think when belts start flying that's a good sign to get a new tensioner.
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Old Aug 5, 2008 | 06:21 AM
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why would a 6 speed be different from an auto???


If you've got a 6spd as I do, then you won't need the overdrive pulley for the alt and your electronics will be just fine. My underdrive pulley only added to my lack of traction. I just bought another "fix traction issues" mod recently though I should be able to put my full bolt on power down on the track nicely now[/QUOTE]
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Old Aug 5, 2008 | 06:51 AM
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Summit here for a couple of weeks and so far it is great. No charging issues and quality piece. I did feel a difference and all 25% underdrives should give the same gain.
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Old Aug 5, 2008 | 12:33 PM
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good info
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Old Aug 5, 2008 | 12:57 PM
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No charging issues here. With my cam I idle about 950. Subtract 25% from that and my alternator is spinning about the same as when stock at 700.
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Old Aug 5, 2008 | 06:17 PM
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Originally Posted by 9secondsflat
why would a 6 speed be different from an auto???


If you've got a 6spd as I do, then you won't need the overdrive pulley for the alt and your electronics will be just fine. My underdrive pulley only added to my lack of traction. I just bought another "fix traction issues" mod recently though I should be able to put my full bolt on power down on the track nicely now
[/QUOTE]

because an a4 in gear will idle at about 500rpms which is often not fast enough to keep the alternator charging like it should unless the rpms are kept higher with an underdrive pulley. An M6 always idles at roughly 800rpms which is always fast enough for the alternator even with an underdrive pulley.
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Old Aug 6, 2008 | 12:21 AM
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I have the SLP UD pully, A4. Yeah charging sux at night wth head lghts on but what bothers me the most is my coolant temps rise fast when sitting still, drop pretty fast once moving again though. Knowing what I know now, probably wouldnt do it again.
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Old Aug 6, 2008 | 12:50 AM
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are there any effects on the cooling system?
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Old Aug 6, 2008 | 12:54 AM
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Originally Posted by thebulgd
I have the SLP UD pully, A4. Yeah charging sux at night wth head lghts on but what bothers me the most is my coolant temps rise fast when sitting still, drop pretty fast once moving again though. Knowing what I know now, probably wouldnt do it again.

Yep..... Nobody talks about this but it is part of the reason I am now dropping big bucks on a better radiator hot especially with the A/C on!!!!!! SUX but it is the price we pay for more power.
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Old Aug 6, 2008 | 05:36 AM
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Well, get the 160F thermostat and tune your cooling fans to turn on earlier(180F or so), problem solved, I dont have any problems with my cooling system, the t-stat helps alot
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Old Aug 6, 2008 | 06:38 AM
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Yea I have the 160 but fans haven't been adjusted yet. The dummy light reads really no different than before.
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Old Aug 6, 2008 | 09:26 AM
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i have an m6 and a 180 stat. the fans are set lower and my autometer guage reads no more than 190-195 no matter how hot the day or how bad the traffic! i do have a little issue at idle though when the sub is cranking you just watch the volts bounce with it.
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Old Aug 6, 2008 | 03:22 PM
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Originally Posted by Ironxcross
are there any effects on the cooling system?
NO! thats that
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Old Aug 7, 2008 | 02:08 AM
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dimed lights is the only thing i had problems with....spins alternator alot slower then the stock pulley...so if you need radio, wipers, high beam/lights all at the same time you gonna hav dimed lights bad....i put my stock ones back on...not worth the trouble in the long run..save the money and invest in a bettr mod
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Old Aug 7, 2008 | 02:11 AM
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ps...i gained more by removeing my powersteering and ac..and it was free, just depends if you still want all that stuff lol...i can live without it..now i just hav crank/alternator/water pump
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