i want to get underdrive pulleys but i heard if u get one for your alternator u can run a high output system is this true

 

From my LIMITED experience i'd say its not a good idea to combine the two, either one or the other. From what i understand a new pulley gives more power to the drivetrain and less to the accessory system (radio included)...

I've seen it rob a system of power in one car so far, but only one so i'm not passing a solid judgement yet

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http://www.tcnj.edu/~esposit3

• '89 Trans AM, 305 TPI, 5-spd
• '86 Firebird, 2.8, Auto

 

I have the power and amp pulley set by March in my 88 IROC and I don't have any problems. Well, I shouldn't say that. The worst thing that has ever happened to me is at night if I am sitting at a light, my headlights dim if it is cranked pretty good. Other than that, I have no problems with it and my battery is always charged. Just a side note, I am usually running a 600 watt amp, but sometimes it is at 1100 watts. Neither seems to make a huge impact. Good luck

Matt

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irocet@hotmail.com

drive.to/Stang_Kilr

88 IROC-Z -- 350 L-98, 700R4, Flowmaster, K&N, MAF Sceens Removed, Airfoil, March Pullies, Comp Cams Magnum 1.6 Roller Rockers, Bosch Platinum Plugs, Accel 8.8 mm Wires, Hypertech Cap & Coil, Hypertech Chip, Hotchkis Strut Tower Brace, One Loud Stereo!

 

The purpose of underdrive pulleys is to run the accessories slower in order to give a bit more power to the engine. The alternator counts as an accessory, so you'll be taking from your alternator and giving to your engine. You can make it work, but it's not a good idea if you have any kind of system.

 

They are right about it changing speeds and developing more horsepower. If you are really wanting to put them on (they actually made a noticable difference on my car) then do it. If you do, make sure you get the power and amp set, because that set has a pulley for the alternator that lets it run more where it is supposed to, unlike the two piece set that doesn't change the alternator. Just my thoughts. If you are doing a big system, you will need another (bigger) alternator anyway, but I see no reason why on a good system that they wouldn't work, they do fine for me.

Matt

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irocet@hotmail.com

drive.to/Stang_Kilr

88 IROC-Z -- 350 L-98, 700R4, Flowmaster, K&N, MAF Sceens Removed, Airfoil, March Pullies, Comp Cams Magnum 1.6 Roller Rockers, Bosch Platinum Plugs, Accel 8.8 mm Wires, Hypertech Cap & Coil, Hypertech Chip, Hotchkis Strut Tower Brace, One Loud Stereo!

 

what if your get the pulleys, and you get a 145 amp alternator and one of those capacitors either .5 or 1 farad? would it matter then?

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87 IROC-z 305 TPI 5spd Borg warner 9-bolt 3.45 posi 4 wheel disc,8.8 Accel wires , bosch platinum +4 plugs,gutted air box,TB coolant bypass ,polyurethane tranny and torque arm mounts, k&n oil filter,synthetic oil 10w30, futura GLS super sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works

 

I would bet that caps would help with the setup you are talking about since they help sustain power draws without relying on the alternator/battery in the first place.

But the underlying question is just how much stereo power do you plan on pushing?

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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

I had the pully on my 105 AMP alternator and my Car sucked at charging so i poped out 300 bucks to summit raceing and got a 140 AMP Alernator figuring hey that will fix it guess what it didnt do 1 damnd thing. So i ended up takeing the pully off and now my car charges fine but my volts are still low when BASS his i nd a cap maybe someday. The alternator pully is only worth 1HP and when i took it off my car i didnt notice a difference. MOSt the gain is from the crank pully.

 

Been there. Done that.

If your alt is undersized, a cap will be useless, and may in fact make the problem worse.

For a street car with a big stereo, from experience, i would recommend not using power pulleys.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 3/14/01)

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