SmokeySS

iTrader: (7)

I see there are two popular sizes for underdrive pullies available and want to get a 25% as it would free up more power. However, will I have a problem at night with headlight dimming or anything negative like that? Or, should I want to run the a/c during the day, will it bog or anything? Is it also necessary or recommended to get a new serpentine belt for the installation? If so, what size?

00454sscamaro

if you buy a underdrive pulley most likely it will tell you the belt size(as mine did) and no there are no adverse affects from them unless you arleady had or have a eletrical problem before installing one, or a huge eletrical draw much greater then stock.

SiL3NtXWS6

iTrader: (17)

yes, you need a new belt. Thunder racing has part numbers listed on their site

you should not have any electrical problem unless you have a big sound system

warp10

iTrader: (5)

25% UD here and no electrical problems. Idle at 750 RPM and lights on, no problems.

FastKat

iTrader: (10)

Gotta dig this one up... is ATI the only one with a 10% underdrive? It seems like everyone has a 25% underdrive and I wanted something a little milder... maybe 10% or 15%. Any suggestions?

(btw, I have a Corvette pulley and F-Body accessories so I need a new pulley one way or another)

NEGEN@SDPC

iTrader: (9)

this is chris with sdpc.. i have both the 10 and 25 instock. pm me if you want one. i also have the belts just let me know....
thank you.
chris
1-800-456-0211 ext353

Ragtop 99

iTrader: (7)

I have seen overdrive pulleys for the altenator. That allows you to underdrive the waterpump and A/C, but have close to normal electrical.

lsx24

iTrader: (45)

ATI is the only one I know about with the 10%, but I like better the underdrive 25% overdrive Alt pully.

Cobra4B

iTrader: (9)

FWIW I run HPDEs w/ my car so I wanted the best damper available... I have a 10% underdrive ATI on the way from SDPC.

jimmypop13

iTrader: (17)

i have a pretty powerful stereo setup in my car, would something like this be a bad idea, even if I got the overdrive pully for the alternator?
-Chris

Grimes

iTrader: (3)

I would do the 25% and get the alt overdrive. I have a decent stereo - sub and 2 amps, and I have a 25% ASP. Admittedly I'm a M6.

lsx24

iTrader: (45)

No... with the overdrive alternator pulley you will be fine.

FastKat

iTrader: (10)

I just went with a brand new stock balancer... got it for $40. I would be reluctant to go all the way to 25% UD with my forced induction setup. FI cars often have cooling issues as it is, and I didn't want to slow the water pump down that much. If the 10% pullies weren't $200+ I probably would have bought one... I'd have paid about $125 but that's it.

vettenuts

iTrader: (4)

I spent a lot of time talking to ATI at Carlisle when I bought mine, the reason they don't offer a 25% under drive (or at least didn't, they were considering making one when I spoke with them) was their in house testing show that it wasn't nearly as effective damping the crankshaft harmonics, which is its primary function. I went with the 10% under drive ATI and pinned it, very high quality piece. If you are FI, did you consider the 8 rib ATI that is made for FI setups?