Fosnot

iTrader: (15)

So I'm looking at replacing my stocker, as months ago the voltage would flicker in the 13s as if my system was hitting hard and fast (really quick voltage fluctuation) but nowit will rarely get the voltmeter to 13, usually sitting in the 12.5 to 12.9 range with no extra load on it (just engine running, stereo off, etc, etc)
I found several threads in here saying a 2000-2003 truck alternator, 4 pin, 145 amp. If there is a bigger one, OEM, that'd fit I would be interested in that as well.
Anyone in here have a list of alternators (or trucks that would have them) so I don't sound like a when I go in there.
Or worse yet, pick up the wrong part...
(Already did the big 3, so exciter wire issues won't be a problem.)
Thanks!

wssix99

iTrader: (5)

Do you have any accessories that demand a larger alternator? The truck alternator is larger - not more durable, so if you don't need the juice, it will just suck more power from the engine to make electricity that will never be used.

Fosnot

iTrader: (15)

Thank you for answering my question... with a question.
Yes I have an 1100w (Rms) amp among other things.

And I'd beg to differ on it being more durable.
Does anyone have an answer?
I also heard a 145amp off a 2006 Cadillac ESV would work?

sjsingle1

iTrader: (1)

the truck alt is bigger........therefore has bigger bearings.......and a bigger rectifier.......i would qualify it as being more DURABLE

Fosnot

iTrader: (15)

And bigger diodes
But seriously, any confirmations? I need the bird back in comission.

safemode

iTrader: (1)

I have two amps that add up to more rms than what you have and my stock alt never budges. My guess is that the alt was on it's last leg for a long while (maybe due to charging too many depleted batteries in it's life) and finally kicked it. I dont think the stock alt would not handle your stereo.. 1100w rms is decent but music rarely hits that high and when it does it's momentary (which the cap you should have takes care of).

Larger alternators dont produce electricity you dont use. They only produce as much electricity as needed, when they are spinning fast enough to. That last part is the downside to larger amp alternators. They dont produce as much electricity at low rpm so you may have idle performance suffer.

They get around this by using a smaller pulley. This is why they usually have bigger and better bearings and what not. Of course, it's not a "positive" when compared to stock because it's spinning faster, so any benefit of having them is negated. So higher amp alternators aren't generally going to outlast lower ones. In fact, the higher heat caused by them (assuming you need the added current) will reduce it's life faster.

Fosnot

iTrader: (15)

Had to go to ls1.c
KG3 4 pin from a 2003 2500 chevy...

safemode

iTrader: (1)

an alt with bigger bearings isn't going to outlast a stock alt unless you change the pulleys (or they happen to be the same already)....and then you may have issues with idle power. You wont know till you try as it would be vehicle/alt/idle rpm specific.

A good rule of thumb is that the higher output the alternator, the higher the idle rpm has to be to make the same power as stock at idle.

ie, you may be able to run all your accessories at idle with the stock and maintain full charging voltage. With a 200amp alt or something you probably barely make charging at idle (if the pulley is the same) with no accessories on, or maybe just one.

Using the smaller pulley fixes that, but makes the whole point of getting something bigger and more "durable" moot.

99Bluz28

iTrader: (35)

When looking for a HO Alt. always find out it's turn on rpm, and amperage at engine idle before making a purchase. FYI, if you idle is below 800rpm you'll probably need to blip the throttle to turn it on after starting the car.

wssix99

iTrader: (5)

There is a difference between HO (High Output) and HD (Heavy Duty).

Rather than cannibalizing another car, I'd suggest figuring out what you want for output amperage and longevity. You can even get higher output and heavier duty parts on the stock alternator! AlternatorMan has enough options that you can get whatever output and duty you need in whatever package you want:

http://www.youtube.com/user/alternat...end=2&ob=1#p/a
http://store.alternatorparts.com/cs1...lternator.aspx

IMO its a lot easier to go with an upgraded version with better internals than to deal with mounting a different design on the car. If you call this guy up, he should be able to provide you with recommendations.

Fosnot

iTrader: (15)

This has already been discussed in other threads the KG3 alternator bolts right up to the LS1 block, 145amp off a truck, HD parts, etc etc.
Its not really cannibalizing it if its from a wrecked out truck at a junk yard.

And for 40$ this ain't bad.