Alternator Size

Let's see if this works... The chart looks perfect in the reply box.

It shows the 130 puts out 187 at 3k rpm.
The 200 puts out 207 at 3k.
It seems to me the 130 should be plenty.


Edit:
The chart came out stupid once the post was published.
I copy/pasted from the site given earlier in this thread, for those of you that want to look.

 

For my needs, the 130 amp is perfect, and PA has a 2 groove pulley option. I have a hot ignition, electric fuel pump, and I want to put in halogen head lights. I also plan to add the A/C unit back someday.
Ken

 

I'm just waiting for my 3G to show up, I can post some pic's when it gets here.

 

Your biggest increase for wire will be from the alt. to the battery and to any heavy amps you put in the trunk. the rest of the factory wiring should be fine.

Tip #2....when getting the 130 amp alt off you donor 3.8 engine, take the time to pull the cable going to the alt.(about 4 feet) all the way to the fuse box. My pull-a-part didnt charge me for the couple I got with mine.
Robert

 

Remember that if you have an ammeter you will have to take it out or run #2 cables to and from the ammeter that reads to 150 amps. (that is the same as running BIG battery cables from the battery and alternator under your dash)
Most folks just replace the ammeter with a volt meter. I am looking for a shunt type ammeter so I can run signal wires to the guage unit but I haven't found what I need yet.

 

i like volt meters better myself, but that's just me

 

Volt meters only tell you half the information you need to know when a problem exists. An Ammeter tells you the other half of the story. It is best to have both in my opinion.

 

good point, but when upgrading to the 3G & up i wouldnt run those big cables for it... but just IMO

 

Me too! Having cables with 130 amps under my dash shrieks "DANGER, FIRE HAZZARD!"
There are enough things under there that can go wrong as it is. That is why I use mechanical guages - well and the known accuracy thing.

 

do higher amp alts put any more drag on the engine?

one of my teachers was saying how the more electrical demand there is on the alternater it puts more drag on the belt and becomes harder to spin. the pulley on any alt ive ever had spun with no effort at all.

 

well i guess that would all depend on what you're running. im sure there's more drag on an EFI car with a 130 amp alternator versus a carb'd car like mine with the same alternator

 

The higher the amperage alternator the greater drag potential under a load. Most high amperage alternators are driven by dual v belts or a serpentine belt to reduce slippage under load.

 

One thing to remember, The higher amp the more load that the belt has to endure, That being said i run the 100 amp from Power Masters. If my battery is just a little low it will case the belt to squeal. I have tried all different types belts, The only belt that will stay that i have found is the Top Cog, If i make a hard pass with any other of the cogged underside belts, They slip so bad it will actually burn the belt in two. As long as i keep the battery charged, ( i use a small generator when cooling or heating my nitrous bottle in the pits) I have no problem what so ever. But i would be afraid any higher amp might cause me problems, By the way i only have one belt around my alt. pulley. I have no room for two due to the blower pulley. As always this is just my 2 cents other opinions will vary.

 

I did the amp gauge thing in my 75 once... Stock alternator, and the gauge still caught fire.
Burned through the oil gauge and the oil pressure shot hot oil all over the inside of the car, while the dash was burning.
I had to manuver across 3 lanes of rush hour traffic in Memphis.

What a mess!
I only do volt gauges now.
Oh, and copper tubing for my oil press gauge.

 

The thing to remember is that under "normal" conditions the alternator doesn't work very hard. The more amps you are using the more amps the alternator has to push into the battery. A standard 60 amp alternator in a stock application will rarely have to push more than about 20 amps. But if you have added components that need more then it will put out somewhere near 65 amps at speeds above 4000 RPM. An alternator that is rated at 60 amps will usually run fine with one belt if the components running are stock. If you add a high output ignition and amplifier for your tunes then you may have to run two belts. Those alternators with 75 and higher output will need 2 belts to keep them from slipping. The 130 amp and up alternators use serpentine belts in order to drive the alternator at high amperage uses.
Even at that you can use belts if you give them enough pulley contact and use a larger pulley which gives you more leverage on the alternator.
When drag racing if you can use a field cut-out switch to disable the alternator you won't have to worry about it slipping. On the alternators that are internally regulated you would have to use a solenoid to disconnect it from the battery to disable the charge and run the lap without it. You need a good battery to do this but it is one way to keep it from burning belts or comming apart at high rpm. If it isn't working then it is less likely to get warm enough to come apart at high rpm.