LT1-LT4 Modifications 1993-97 Gen II Small Block V8

underdrive pulley question

Old 09-26-2006, 03:17 AM
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Default underdrive pulley question

does brand matter?


why does it show 3 here -

http://www.car-stuff.com/performance...9&skipped=true


and 2 here -

http://cgi.ebay.com/ebaymotors/March...spagenameZWDVW
Old 09-26-2006, 03:54 AM
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for these piggy back ones, the brand really doesn't matter. Piggy back, meaning, the stock dampener is bolted on top of the pulley. I think the cheapest one is Performance Specialty's. I know people say they are about worthless for power gains, but the increased PS/AC pumps life is where the real benifit is. the ALT pulley(the small pulley) is a good idea if the idle is stock. I donno whats going on in the fist pic. I think one is for the A/C, but I can't really tell.

Also, since you have 3.73's, I personally think it is a god idea to have an underdrive to slow stuff down, mainly cuz it is always reving higher, vs the stock gears. Some say moving the dampener outward can make it less effective, and put extra strain on the bearings. I have seen no proof in either direction.
Old 09-26-2006, 05:13 AM
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so is this a waste of money?
Old 09-26-2006, 05:35 AM
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most will say yes, but since your already to the point of not having alot of ways to improve(meaning you have just about every mod except a cam and compression boost) why not? I was gonna get one and do some testing at the track. I could prolly change it in the staging lanes on a busy night. for what $50? your not gonna see huge gains, maybe $25 per HP. Take a look at this. The peak # could fall within the dyno error's. but you be the judge. http://www.ws6.com/mod-2.htm
Old 09-26-2006, 06:10 AM
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now i cant find where to buy the hypertech power pulley
Old 09-26-2006, 06:59 AM
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http://store.summitracing.com/partde...5&autoview=sku
Old 09-26-2006, 09:16 PM
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Depends on what reduction you have. I have a 34% Underdrive.
Old 09-26-2006, 11:26 PM
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What kind of Serpentine belt is needed with that pully i am assuming the stock one can no longer be used. Thanks
Old 09-27-2006, 07:06 PM
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sorry, no idea. i would THINK, the way to calculate the belt you need is by measuring the circomferance of both pulleys, then use the percent of amount the belt goes around the pulley. Meaning, if it goes 3/4 the way around, shorten the belt 75% of the difference between the pulley circomferance's. see what I mean?
Old 09-27-2006, 08:40 PM
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I have a 34% underdrive, and needed a 60" Belt.
Old 09-27-2006, 09:18 PM
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how would i know what % underdrive im gonna get with one of the sets?
Old 09-27-2006, 09:30 PM
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Most of them say what they are.
Old 09-27-2006, 10:42 PM
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Make sure you save the original. IMO its a waste of money unless the car is mainly a strip car most of the time and you are not running any kind of stereo. I actually threw mine away after 2 weeks because I didn't think it would be worth the hassle to try and sell it and have someone else disappointed. I run a dual optima system and had issue with it charging at idle and sometimes on the highway. Put the old one back on and the issue was resolved. This was just my experience others have had better.
Old 09-28-2006, 09:19 AM
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You must be sucking some juice if it's having trouble on the highway..lol
Old 09-28-2006, 07:06 PM
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Originally Posted by ToxicTA
Make sure you save the original. IMO its a waste of money unless the car is mainly a strip car most of the time and you are not running any kind of stereo. I actually threw mine away after 2 weeks because I didn't think it would be worth the hassle to try and sell it and have someone else disappointed. I run a dual optima system and had issue with it charging at idle and sometimes on the highway. Put the old one back on and the issue was resolved. This was just my experience others have had better.

im running some kind of stereo, and ive already done everything but a cam, i figured why the hell not
Old 09-28-2006, 07:13 PM
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I ran the auto speciaties set. Well I didn't install the alt pulley so with the high beams on or the fans on high(I'm running a manual fan switch) it would dim for a second until the revs came back up.

So I would def. install the bigger alt pulley if you have a stereo that draws more than factory.
Old 09-29-2006, 09:51 PM
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not sure what the prices are on others, but i ordered the BBK U/D pulley. i think that was 60ish shipped from summit.
had it on the car for almost 2 years now. had to get my idle bumped up 75 rpm at idle, and have went through 2 batteries. that i beleive were due to the pulley.
personally i couldnt tell much, if anything i felt the revs go up quicker during normal acceleration.
Old 09-29-2006, 11:30 PM
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Originally Posted by camzaro28
not sure what the prices are on others, but i ordered the BBK U/D pulley. i think that was 60ish shipped from summit.
had it on the car for almost 2 years now. had to get my idle bumped up 75 rpm at idle, and have went through 2 batteries. that i beleive were due to the pulley.
personally i couldnt tell much, if anything i felt the revs go up quicker during normal acceleration.
You felt the revs go up quicker during normal acceleration? I think your trying to pull my leg now.
Old 09-30-2006, 01:47 AM
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I don't see how the underdrive pulley would kill the battery. If the under drive is not charging enough, go with the OD alt pulley. if you already have it, I'm very confused... it may drain the battery, but Kill it, so it won't hold a charge?
Old 09-30-2006, 11:29 AM
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Don't get a POS piggy back pulley that just adds weight. If you get one, do it right and get the ASP 23% pulley, it replaces the stock ballancer, its not a piggy back one.

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