After a 1,500 sound system being on my (I believe) stock alternator, it's quickly wearing out after 3 weeks or so...
I found a local guy on CL selling a 4.6 alternator, which I've heard are better than the 5.0 stockers. Will it swap on directly, and what's the amp rating on those? 130 or 160?
It probably won't have the output you're looking for. Some of the smaller case alts actually can have less output than a big case 3G (our alts can put out ~160 amps stock)
What makes you think it's the system eating the alt's? How are they failing? Or is your stocker getting ready to take a dump? It could be that it was marginal before (maybe it had already dropped a diode) and now the system is finishing it off.
I'd look at aftermarket 160 - 200 amp 3G alts, or just get a parts store stock replacement with a lifetime warranty (Shipping an alt out for warranty work is a pain). One considerating: with aftermarket stuff, they often have near 100 amps of output near idle. A parts store version might not (at least not without overdriving it).
Well for one, saying "4.6" alternator is being vague since the 4.6 had no less than 3 different style alternators from 96-present.
Now, while the later 4.6's use a 6G style aternator which is more effiecient, it still only puts out 130 amps. And the 96-98's used the same exact 3G that our cars came with (different mounting setup for 4.6 alts).
And I agree with JT, your stock alternator was probably on it's way out before the sound system was installed.
I think the stocker may have been on its way out to begin with, IMO. The car would idle funny at times and a/c and accessories messes with with idle a good amount. Clicking on my headlights would cause the battery guage to drop a tiny, tiny bit.
As for a 130 being enough... I've got a friend of mine who currently is running a 3,000 watt system with 2 15 inch subs in his Ranger. The guy's a genius when it comes to sound/electrical systems. He works more wiring magic with cars than I've ever seen. He says a 130 amp alternator should work fine for what I have. A 160 would be good, but the 130 will work fine.
The system's on its way out in the next couple weeks anyway. I've got a friend who has been in the process of doing a TT swap on his 300zx, and the system's from his car, which he's loaning me until his car is up and running.