qwikz28

iTrader: (12)

like the title says... i'm doing heads and cam on my car but i'm worried about the power draw cause i have an aftermarket stereo system. i'd rather not do the pullies but am i leaving a tremendous amount of power on the table? opinions?

btw- my car is strictly a street car and only sees track time for my own curiousity

ShevrolayZ28

iTrader: (4)

You can get an alternator overdrive pulley to compensate for the crank underdrive pulley and you'll be good.

jmm98LS1

iTrader: (28)

+1 on the alternator pulley, should alleviate any charging problems so long as your alternator is up to the amperage requirements of your stereo. It's been said that normal gains with pulleys are around 5-10rwhp (~ a tenth at the track).

qwikz28

iTrader: (12)

sweet... i hope its not too hard to install

thanks guys

ShevrolayZ28

iTrader: (4)

You will need puller tools and a longer bolt to install the crank pulley. No biggy. Good luck.

lsx24

iTrader: (45)

I wouldn't say crutial but it sure does help a lot, 10 rwhp is 10 rwhp, but not quite as much with the overdrive alternator pulley. If you are that worried about it I would pass, what's another 7-10 rwhp when you have the piece of mind you are drawing a bigger charge than your alternator can handle.

orangeapeel

iTrader: (18)

I dont have one on my SS.


Also. Don't get an overdrive for your alternator and an underdrive for your crank. They are gonna cross cancel each other. Think about it.

orangeapeel

iTrader: (18)

Bottom line is don't run a UD if you feel that you really want to keep your system at a decent charge. It may also be just fine too. You said yourself that it rarely sees the track. Don't waste money on it if you ask me.

lsx24

iTrader: (45)

That's the idea, but just for the alternator, as the other accessories will still take advantage of the 25%.

qwikz28

iTrader: (12)

money isn't so much the issue cause i already bought it... i am worried about the installation and whether the positives will outweigh the negatives. an overdrive pulley on the alternator and a underdrive pulley on the crank almost sounds retarded.

jimmypop13

iTrader: (17)

it may sound retarded but people do it! Is there actually a good reason for it? Or do they really completly cancel out each other?

lsx24

iTrader: (45)

read my post #9.

qwikz28

iTrader: (12)

they won't cancel each other out per se... i would lose some of the benefit of the 25% underdrive by installing a slightly larger alternator pulley. i would still see benefit, but not enough for my lazy ***. had this been a race car of some sort or had i actually cared enough about my dyno numbers then maybe i would... but in my case its just retarded to do that and pick up another 5-7hp. this is what i derived from this thread and thats my conclusion... thanks again guys

jimmypop13

iTrader: (17)

i agree

kawasakiklx

iTrader: (8)

Think about this... say the crank was 25% UD, that is a large difference considering the size of the crank.... that being said - even if the Alt. was OD it's such a small pulley that even if it was a 60% OD it probably still wouldnt cancel out the UD. It's all about ratios my friends.

+ dont make me feel stupid... I did it. I believe the pulley was actually smaller to make the alt spin faster... that would only effect alt. wouldnt it?

ShevrolayZ28

iTrader: (4)

That's the idea. You gain from underdiving the other accessories, but the alternator still spins fast.

DuronClocker

iTrader: (25)

Under load the alternator is one of the hugest parasitic accessories. Although the power gained from the combo may not be noticeable (though possibly measurable), it is still going to reduce the RPMs of the other accessories, and make them last longer. I know a lot of people have problems with the power steering pump, and making it spin slower will only help that system.

I installed my motor with the UD pulley and new water pump and power steering pumps. Within a few weeks, my alternator went bad. I knew it was going to happen because it would've been 5 minutes of work with the motor out, and I didn't do it then. Keep in mind mine also had 110k miles on it, so I wasn't too upset.

I went and bought an Alterstart 200A alternator to replace it. 110A at 800RPM engine speed. My car idles around 950-1000. 25% UD pulley puts alternator speed at an effective 700-750RPM (engine speed)...if I explained that well enough, I shouldn't have any problem running 50-100RPMs below what it makes 110A at, as it is still plenty more than the factory alternator. Spent a little over $300 shipped including the alternator and the 4-guage charge wire that I hooked in parallel with existing wiring.

Hype

I don't think you can say that. Running things slower than they are intended can often times lead to problems.... for example, I'm sure you've heard of a black out.... but have you heard of a brown out? At least with electricity running things below spec can sure cause some problems.

Now I'm not saying UD pullies are bad, just that I won't be doing it

Grimes

iTrader: (3)

I agree that you can't make a blanket statement, but the power steering pump really does suck on our cars, and I too am convinced the ud pulley helps it and the other accessories live longer, happier lives!

S99TA

I say ditch the stereo system its extra weight slowing you down