75 amp alt. with under drive pulley's

Sonicaceman · Apr 21, 2009

okay the 1st thing everyone is going to say is upgrade the alternator. i know i plan on it, but the funds don't allow it and another $200 this year after a new rear end install would be pushing it. anyway i have the stock 75 amp alternator with under drive pullies and my voltage at 7-800rpm idle is only 12-13 volts max. i want to get the 95amp pa alternator, but i'm wondering if that is enough to bump my voltage up to about 14 at idle. my msd ignition doesn't work right and i believe it was burned up because i was running too low of voltage to it at idle.... my battery after less than two years crapped out too. i don't have any high end stereo, just a cd player, an electric fan, and one toggle switch for some inner lights on my headlights. has anyone upgraded from the 75-95 who has under drive pullies and if so did it fix the voltage problem at idle? there is always the 130, but i know the bracket needs some modifying, it's more money and i'm not running a ton of electronics. what do you guys think?

Funanin · Apr 22, 2009

ok, no matter what the current level of the alt it should read 14.4v or higher when the engine is running unless there is something running pullin a huge draw (like your electric fan). Those fans do pull alot of current so if you have a regular battery and the fan is set to only turn off from temperature and not the ignition key you might want to upgrade to a deep cycle battery or set the fan to turn off sooner/when you turn the ignition off.

As for the high current alternator that is 130+ the modifying of the bracket is SOOO easy, so dont let that discourage you from buying a single wire high power alternator from powermaster or something.

Sonicaceman · Apr 22, 2009

alternator

thanks for the info. i'm probably going to wait and get the 95 amp one when i can afford it, it is working and a local mechanic who specifically works on stangs and has a dyno at his shop said it should be fine. there isn't much of any electrical on my car so for now it should be good. i would get the deep cycle battery but it isn't worth the cost in my eyes, my friend has gone through three of them, so i'm not impressed with them too much, my battery had a two year warranty and i got it replaced for free so i'm not too worried.

Chasinpapa · Apr 23, 2009

To alternate or not to alternate

O.K. gentleman, I'm new here. Joined just a few weeks ago. This seems to be the only site on the net where you can get educated answers to questions about the best cars ever built. I have an '88 5.0 vert with just a few add-ons (Ford Motorsports headers, cold air) because there is not alot that you can do to speed density without going to mass-air, which I am going to do but, probably not this year. So, what is the bottom line on adding pullies? Will my stock alternator be enough? I still have the stock sound system mainly because I'd rather listen to the music only a 5.0 can make. Thanks for any replies.

TRWXXA · Apr 25, 2009

An alternator upgrade is something I think everyone should put on their "must do" list. The stock wiring is terrible (barely adequate for the stock setup), and the 75 amp alternator is overtaxed at idle if you have only a couple of high-draw items turned on -- headlights, HVAC fan, etc.. The stock alternator wiring plugs have a high rate of failure.

If you put on underdrives, at the very least put in a 95-amp unit with a wiring upgrade. You'll recover the electrical output ability lost by reducing the alternator RPM. If you plan on putting in an electric cooling fan, go even bigger.

HISSIN50 · Apr 25, 2009

If going with less than a 130 amp unit, you should also decide to choose either the E-fan or underdrives.

Hit the junkyard and get a couple of 130A 3Gs. Grab donor wiring while you're there or make your own 4 AWG harness.

Chasinpapa · Apr 25, 2009

Thanks guys, much appreciated.

nunly94gt · Apr 25, 2009

WHat car had the 3G? The 5.0 Explorer?

Sonicaceman · Apr 28, 2009

alt upgrade

hmm, a lot to think about. i think i will go with the 95 amp unit next year. i like to buy brand new stuff so a new pa unit should get it done. i like to do most small projects myself, and a 95 will be plug and play, i wont' have to change anything and it should work good. thanks for the input.

HISSIN50 · Apr 29, 2009

Sonicaceman said:
hmm, a lot to think about. i think i will go with the 95 amp unit next year. i like to buy brand new stuff so a new pa unit should get it done. i like to do most small projects myself, and a 95 will be plug and play, i wont' have to change anything and it should work good. thanks for the input.

As TRWXXA said, you still need to upgrade the wiring.

Nunly, your old stang had a 3G (94-95 Mustangs have them).

nunly94gt · Apr 29, 2009

ok, and it will bolt up to the 88 just fine?

DARCA · Apr 29, 2009

I don't know all the specifics but you are going to have to modify the bracket if you use a 3G out of a 94-95 stang.

HISSIN50 · Apr 29, 2009

nunly94gt said:
ok, and it will bolt up to the 88 just fine?

With slight bracket and wiring modifications.
Do a search for 3G retrofit. There's an article in the useful threads sticky as well.

nunly94gt · Apr 29, 2009

Thanks man!

75 amp alt. with under drive pulley's

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