Underdrive pulley consensus

[phoonTy]

So I have/had a complete underdrive pulley set on my Ty. A month ago, my alternator died, and, having a complete mental lapse, didn't take the alternator pulley off before exchanging my core. Now I'm without the smaller alternator pulley, and experiencing serious voltage drops at idle sitting at stoplights, especially with the headlights on.

i have the stock pulleys in a box at my parents house. is there any benefit to having underdrive? or should i avoid the $78 for a new pulley and go back to stock?

i ran a search, but didn't find much other than keep stock.
(pulley topic)

 

[phoonTy]

16 views, two votes. :-? everyone gone for the holidays already? i'm still digging with the search, be we all know how that goes. just wondering if anyone has had direct experience with the good/bad of underdrive pulleys.

 

[cloneman315]

i DID A TEST 2 DAYS AGO LOST AMLOST 2 VOLTS AT IDLE GO BACK TO STOCK 4 SURE

 

[Loeryder]

Go back to stock.

It will be harder on the alternator and what you gain in mechanical load you lose in electrical load.

Another voltage at idle concern may be if you have a high amp alt.
They actually put out less power at idle than the stocker, but as they spin up is where they make their amps.

 

[90stangGT]

Im generally opposed to underdrive pulleys as there are a million different ways to increase power. I don't feel it worth the minor gains considering the possible loss of charging capabilities at idle, depending on what other electronics you may have on board and what alternator you have.

 

[Captain Morgan]

i have never heard anything good about underdrive pulleys on SyTys

 

[phoonTy]

i tried a stock alternator, and my amps weren't even close, so i went with a 140amp powermaster, but even that's not enough with the pulleys.

thanks for the advice guys, looks like i'll be saving a few dollars and putting in a little wrench time. always fun to work on the truck, haven't donated blood to it in a while. haha.

 

[sy2207]

Re: Underdrive pulley consensus

Now I'm without the smaller alternator pulley...

You mean the larger pulley, right?. A larger pulley will spin the alternator slower.

 

[MotorMouth]

I am pretty sure that the idea behind underdrive pullies is to reduce paracitic loss due to accessory drag at high RPM (and sudsuquently free up some HP). Since these motors don't rev all that teribly high I don't believe they are worth it. Pluss they slow down the accessories at low RPM wich means less juice at and off idle. I had them on my LT1 camaro and did't notice a huge differance except at higher RPM (but that was almost 8,000 RPM).

Brian

 

[Sy Guy 0024]

I have one on my LT1 Hawk, too. The only real difference I noticed was the battery discharging when sitting in idle for extended periods. Not real fun when you're stuck in traffic on the freeway :-? I'll not use them on my Sy. I'd say go stock.

Corbin

 

[phoonTy]

Re: Underdrive pulley consensus

Now I'm without the smaller alternator pulley...

You mean the larger pulley, right?. A larger pulley will spin the alternator slower.

no, the stock pulley is larger than the underdrive. when you go to smaller pulley's, a small ratio to large ratio causes the alternator to spin slower, thus creating less amps. that's why i need another smaller pulley for the alternator or to go back to stock, which is what i'm doing as soon as my stock pulleys arrive from my parents house.

 

[bigtime]

I have them on mine and they suck. No charge at idle!

 

[phoonTy]

I have them on mine and they suck. No charge at idle!

that seems to be the consensus. definitely going back to stock now.

 

[msheller]

Re: Underdrive pulley consensus

can we get liteweight stock spec pulleys forour truks?

Thank u

matt

 

[2kwik4u]

Re: Underdrive pulley consensus

can we get liteweight stock spec pulleys forour truks?

Thank u

matt

Depends on how much you want to spend. I'm sure there are a couple guys with the talent to get them machined if you have the cash to make it worth thier time.

They don't make an off the shelf set that I'm aware of.

 

[ViciousV6]

Re: Underdrive pulley consensus

I have underdrive pulleys on my truck, left stock pulley on Alternator, underdrive on the rest, i also have 200 amp alternator powermaster to run all my electrical stuff.

Ralph
ViciousV6

 

[E-Rue]

Re: Underdrive pulley consensus

simple question, and here is a simple answer. if you greatly change the RPM range of the motor, and are willing to idle at 900rpm then by all means go with the underdrive pulleys. they will perfectly complement your motor. i usually use a crank pully only, with good success, but another good option for a more stock build, is a kit with an underdrive crank pully and an over drive alternator pulley.

i recently learned the hard way about alternators.....

aftermarket alternators especially powermaster alternators are the worst things in the world. complete and total garbage. if you think your getting an increase in output you are sadly mistaken. if you need a larger alternator do the reasearch and find the GM make and model of car that uses a similar style/mount but higher output. then go buy that alternator. the aftermarket alternators are nothing but fools gold.

e

 

[TYRODD]

Re: Underdrive pulley consensus

i recently learned the hard way about alternators.....

aftermarket alternators especially powermaster alternators are the worst things in the world. complete and total garbage. if you think your getting an increase in output you are sadly mistaken. if you need a larger alternator do the reasearch and find the GM make and model of car that uses a similar style/mount but higher output. then go buy that alternator. the aftermarket alternators are nothing but fools gold.

e

Yeah, powermasters are terrible, mine lasted 2000 miles :roll:

 

[SY2455]

Re: Underdrive pulley consensus

I have the underdrive crank pulley only and all I needed to do was raise the idle up to 900rpm in park. The truck been like this for years with no problems.

 

[Christian Dionne]

Re: Underdrive pulley consensus

I had a 140a Powermaster fail after 2k miles as well....turns out you need an underdriven crank pulley to not overspeed it. The rpm limit is 18k, which is exceeded with stock pulleys and 6k rpm big buildup. I sent it to Powermaster and they fixed it for free, then I installed the underdrive crank pulley.... no problems since then.