I am looking for an alternator that I can install that will put out more than what I currently have.

It is going on my V8 Fiero. With the car at idle, the voltage (on my Autometer volt meter gauge) will drop to below 12 volts with the following accessories on:

-stock fan
-higher volume (than stock) fuel pump
-CSR electric water pump
-MSD 6AL ignition box
-computer, etc. for TPI induction on the V8
-radio
-8 different AutoMeter brand gauges (I replaced the original gauges with aftermarket)

AND
-brakes / turn signals (as needed)
-headlights (as needed)

When I turn on the radiator fan it really has a large draw on current. With the motor at idle and NO accessories on, the voltage reads good, around 13-14 volts.

I know its alot of small items, but with everything running, it seems to demand alot. So, what I am looking for is an alternator that is able to handle this kind of power demand. I dont want to take the chance to overwork the current alternator and burn it up prematurely by overworking it, or possibly end up killing my battery because it is not able to recharge during driving because all of the energy being used.


Or, let me know if I am just worrying about something that is nothing!

I am not sure if you have V 8 chevy alt or fiero alt either way you are lucky because thier is a wealth of alternators available,you just need to determine what alt you are running and install a higher amp model.
The fiero store has 140 amp alternators available these is more than you need
if a stock chevy set up thier is MUCHO available ..
most of the auto electrical shops have been driven out of business by our desire for cheap parts and low no quality service ,if you have one in your area they will set up exactly what you want for $50 to $100
If you have a chevy alt it is just a matter of finding which model had higher amp alternator many salvage yards have catalogs which have this info
What I would do is find model alt you want and order Duralast rebuilt ,or order from fiero store
What i would do before this is make sure I had excellent battery .I would clean battery cable connection,if possible check water level and electrolyte gravity,, check connections at alternator make sure belt is ajusted properly..alternator bolts are tight..
batt voltage with engine off should be 12 volts
a good system should pull close to 14.5 to 15 when charging
a system with a lot of crap(tech term) needeth a good battery an enthusiast car should have better quality battery ,, this solves many problems
Advance auto and other companies take back many batteries that are perfectly good the original purchaser had a problem he blamed on the battery and when he found out it was not $75.00 battery causing problem he returned battery got refund they can not sell as new so I paid $25.00 for my optima (this was blind luck) check out return battery selection if available ..

[This message has been edited by uhlanstan (edited 08-28-2008).]

quote Originally posted by uhlanstan: I am not sure if you have V 8 chevy alt or fiero alt either way you are lucky because thier is a wealth of alternators available,you just need to determine what alt you are running and install a higher amp model. The fiero store has 140 amp alternators available these is more than you need if a stock chevy set up thier is MUCHO available .. most of the auto electrical shops have been driven out of business by our desire for cheap parts and low no quality service ,if you have one in your area they will set up exactly what you want for $50 to $100 If you have a chevy alt it is just a matter of finding which model had higher amp alternator many salvage yards have catalogs which have this info What I would do is find model alt you want and order Duralast rebuilt ,or order from fiero store

Thanks alot! I dont know why, but I never thought to check the Fiero Store! I thought that a high amp alternator would be more of a hard to find aftermarket situation.

I do have a Fiero V6 alternator. I pulled the serpentine pulley off and replaced it with a V-belt pulley.

The Fiero alternator that I have right now is what would have been put on a 2.8 V6 Fiero WITH air conditioning. I do not remember what the amp rating is, but I assume that it is lower than 140

You do not need 140 amp you need a good battery and a 110 to 120 amp..tops,,, With a top quality battery you can get by with a lower output alternator
Your system is probably marginal..but with an excellent battery you would have no problems
with G M you have many options
30 minute spend cleaning up your system should give improved results,,do not forget GROUND wire and starter juice wire
Normally the regulator keeps everything under control, if you drive at 80 to 90 mph often this is the only problem I see with 140 amp.. you could boil battery
if your stock alternator sends the volt metre from zero to 14.5 when you start the car sometimes you are probably OK..before change alt. check out the stock system
Stock a/c fiero was about 94 amp .. you are probably at the edge but safe gotta go blue berry muffins ready

[This message has been edited by uhlanstan (edited 08-28-2008).]

88 V6 Fiero uses a CS 130 family alternator. Get one of those with the 105 amp output and you should be ok. If you change the pulley on the CS... do not use are tools to install it or you can damage the alternator.

Also... your problem could be other issues like bad grounds and cables. Do NOT trust the dash gauge. Measure at the battery and alternator outputs. If needed attach a piece of wire to the alternator output so you can reach it safely with the car running. Just make sure it can't short if you drop it. Tie it to something to make sure.

You're probably running a 80-90 amp SI series alternator if it was any other year Fiero you got it for. Read Watt Story in my cave for what is going on with alternators at different speeds.

Even if the 105 amp CS falls off at idle, it comes back in sooner and at higher value as you move off idle. The CS will make more power but if you don't also rule out whatever other problems you may have, they will just keep getting worse and kill the car or even cause a fire.

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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 (It's also at the top of every forum page...)

I'm running all the electric items you are as well as electric assist brakes, so I understand what you are going through. I fixed this issue by running a 160amp alternator from Summit Racing as well as bumping my idle up 50rpms. My last V8 Fiero wouldn't start charging until the motor would spin faster than idle, but I think that was a belt routing issue and pulley size issue. My current V8 has just a crank and alternator.
Dave

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1987 GT (my toy-see above), 1987 GT (daily driver), 1986 SE with a VW VR6, certified master technician/shop owner
www.njautobahn.com

First, thank you to everybody who replied!

Ogre: I forgot about the cave. Thanks for reminding me - and for anyone else who has forgotten about it - go check it out, there is alot of useful information there!!!


How many amp does the stock Fiero fan use? I notice a significant drop at my voltmeter (not stock voltmeter) when I turn it on. The reason that I ask how much it uses is because I would like to get an aftermarket fan that has less of a draw.


I am sure that my battery is ok. It is a Diehard Gold and not very old. Is there a way I can check it to tell if its bad? I am not going to go buy another $80 battery with hopes that it will work.

Guru: It seems that you are the only person who actually READ my post where I state just how many electrical items I am running. Thank you!

I wasnt asking for reasons why you would want a high amp alternator - I was asking if I need a higher amp alternator would better suit my current electrical situation in my Fiero.


Anyone have any other ideas / information?

You can't trust ANY dash gauge. Doesn't matter if it's stock. It's how cars are wired. You must start testing at the battery and/or alternator. You need to determine if the voltage is dropping at the source(s).

If the voltage is dropping at one or both those locations, then the alt is potentially under powered for the load on it. Even then the voltage should not drop below 12-13 unless the battery has problems.

Odds are the voltage is dropping little or not at all at the source and you've got bad wiring that is causing voltage drops. F'd up wiring is rampant in old cars. All it takes is one bad joint in the right place to hose the whole vehicle. Replacing the alternator Might help but probably not much or for long in such a case.

The first things to check are grounds between the block and body, battery and body, Alt brackets, and the hot wiring between the battery, alternator and the main terminal that is/was under C500. If any of those connections or wires is a tiny bit crapped up it can cause major voltage drops.

Here's another common trap... The second wire on the alternator's side plug. It's called the Sense wire. If that wire is damaged in any way the alternator won't read the output voltage properly and you'll get some nasty problems. This wire is how the regulator knows what the voltage is coming out of the back of the unit. I won't try to explain all of what it is wired like that for but trust me if that wire or the connection at wither end of it are bad the alt will NEVER work properly. (If you really want to know what it does... look up how you use "remote sense" power supplies.)

one thing I forgot to mention about the Fiero's voltmeter. I have a pulsing voltmeter on my stock 87 GT. I tried a higher amp alternator and it still pulses with the turn signals. The fan does cause it to drop as well. For my own satisfaction, I tested AT THE BATTERY with an ANALOG voltmeter and the pulsing wasn't noticed. The fan did not kick the voltage down at the battery.
Even though this is not your situation, I always recommend to test there first before you go crazy trying to build up a system that is normal and the gauge is the voltage drop.
Also, with a V8 Fiero running an electric water pump, fuel pump and fan, I would most definitely run a higher amp alternator. I noticed a huge difference the minute I started up my V8 car. You could hear the difference in the way my fuel pump sounded when my fan would turn on. After the new alternator...not at all. Get a higher amp alternator and you will notice a difference.
Dave

[This message has been edited by bmwguru (edited 08-30-2008).]

I bought a 95 amp Bosch alternator. Fits the stock plugs and is just fine. No charging problems.

BTW I see you have the MSD 6A. So did I until it went south and cost me major headaches and parts on lost leader diagnosies. I'd get rid of it. Just my .02

Arn