1985 se Alternators...Again! (Page 1/1)
AVaill6 APR 27, 06:04 PM
Hey guys,
i know that the information is in the ether of the forum somewhere. Ive been digging for days and I'm still full of uncertainty and misinformation.
Long story short, blew the alternator brushes apart in my 1985 Fiero SE 2.5 4CYL.
No AC.
looking to slap a new one in but not sure what amperage I need/ if I should jam an upgraded one with higher amperage.
if I have retained any knowledge from hours of reading, in the 85s, they ran 78 amps. does it make sense to put that right back in? or am I going to blow that one shortly after?


so, whats the stock amperage?
should I bother replacing with riginal amperage?
do I upgrade ?
any info to ease the mind would be much appreciated!!!
thanks

[This message has been edited by AVaill6 (edited 04-27-2020).]

Gall757 APR 27, 06:36 PM
Don't overthink this.....

Is your car stock? Rockauto shows lots of alternators that will work...from 78 to 94 amps. The year of the car should make no difference. Unless you have installed a big amplifier, the 78 amp is all you need.
AVaill6 APR 28, 09:26 AM

quote
Originally posted by Gall757:

Don't overthink this.....

Is your car stock? Rockauto shows lots of alternators that will work...from 78 to 94 amps. The year of the car should make no difference. Unless you have installed a big amplifier, the 78 amp is all you need.



Thanks, I usually trust rockauto.
All stock, no accesories other than a head unit.
cebix APR 29, 04:07 PM

quote
Originally posted by AVaill6:


Thanks, I usually trust rockauto.
All stock, no accesories other than a head unit.



Yeah the'yre not too expensive so a new one is a good choice I guess. When I replaced mine I thought about rebuilding the original one but finally thought screw this, better to get a new one. And that was a good choice since it turned out the one in my Fiero was a 40amp unit from the early 70s... Probably only thing the previous owner(s) could find here when they needed one.

[This message has been edited by cebix (edited 04-29-2020).]

theogre APR 29, 06:18 PM
Catalog Amp Rating is Peak/Total Amps and often the alt is not making that unless drive on highway or over ~ 35 mph. Exact car speed the alt will peak depend on many things.

Don't install an old SI Alt on anything that came with them like your 85.

Newer CS-130 are better in many ways.
You don't need more peak amps but CS vs SI at same rating makes more amps at idle so things like HL and Radiator Fan gets full power more often.

See my Cave, CS Alternator, Watt Story and upgrade page.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

fierosound APR 29, 07:06 PM

quote
Originally posted by theogre:

Don't install an old SI Alt on anything that came with them like your 85.

Newer CS-130 are better in many ways.
You don't need more peak amps but CS vs SI at same rating makes more amps at idle so things like HL and Radiator Fan gets full power more often



Agreed. If you're replacing it, may as well "go one better" than original with the CS-130 type alternator that the 1988 Fiero had.

I installed the CS-130 alternator on both my 87 GT and my 84 Indy with 88 V6 alternator.




------------------
My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 05-08-2020).]

theogre APR 29, 07:39 PM

quote
Originally posted by fierosound:
Agreed. If you're replacing it, may as well "go one better" than original with the CS-130 type alternator that the 1988 Fiero had.

But Don't buy CS for 87-88 L4 Fiero. That won't fit older l4 w/ alt ears 180° apart.

Think older L4 uses same as V6 but V6 alt may have "wrong" clocking... If true just remove case bolts and rotate case halves so side plug is right direction.