Alternator Options

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JGC403

JGC403

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I need a higher amperage alternator, I'm going with fuel injection, electric fuel pump, and electric fans, so there is a need for more amps.

What alternator would you use, upgrade a Chrysler square back alternator to 100 amps or so or use a later Chrysler built 90 amp alternator with the plastic back? See link for more info, (bottom of page):
http://www.allpar.com/history/mopar/electrical.html
 
I would swap to a Delco 12si, great alternator, not too hard to fit.
http://www.forabodiesonly.com/mopar/showthread.php?p=1480334

You can get stock ones in 78 and 94 amp, which both charge well at idle. Powermaster makes a 150A version that's well priced. You won't have to have your firewall mounted regulator anymore, and if you have a failure you can grab one at any parts store. They come apart easy, easy to swap to serpentine if you wanted.

So far my 78 amp has done well with high draw electric fans, but since I will be adding EFI as well, I may need to go to a larger one.
 
Hi,

I would start with a couple of pieces of paper first and add up all the current requirements of the EFI system, fans and fuel pump, etc. and see from that how big an alternator you would need.

You didn't mention what vehicle you are planning this for but, on any 45 year old Mopar you are going to have to do some significant upgrading to the wiring system. The ammeter is going to have to go in favor of a voltmeter. Also, things like fans and fuel pumps are best handled by relays and there will be new fused circuits as well. All of this is best planned out on paper rather that kind of piecemeal changes to the car as you add things.
 
I'm planning on going with 100Amp squareback model from rockauto. 100 bucks plus shipping. I'm seen some people suggest different alternators but they have generally been looking for a lighter weight or smaller model for whatever reason they have. I would love to go even bigger than 100Amp but past the off the shelf 100Amp one from RockAuto things get real pricy from PowerMaster.
 
Just ordered one from powermaster ....90 amp 3-wire square back in the black finish. Keeping it kinda stock looking. You can leave the voltage regulator wiring but I am changing the main feed to 8 gauge with a 12amp fusible link. Amp meter is going to be bypassed ... as are the connections in the bulkhead
 
Be careful of some of the Mopar ones. I bought a new 120 A (recall) one for an LA/BB Mopar that is supposed to bolt right up, because a good price on ebay (~$50). I didn't even try because it turned out to be much bigger and heavier than I thought from the photo. Might have been used in tow trucks & such. It has a front external fan, like a GM alternator. If anybody around Sacramento or Bay Area wants to try it, I'll sell cheap. I don't want to ship the beast. If I need more output than a squareback someday, I'll try a small modern Denso type like my minivans use.

TBI EFI has worked fine in my 65 big-block for years with just the stock round-back. I suspect it is only when you install an electric radiator fan that you need more juice. Don't calculate just based on the current ratings, since that is usually a high motor starting current (to size wires and relays). The steady running current is often much less. As long as your battery stays charged, you are fine. I occasionally put a charger on mine to see how long it takes to say "charged", to judge if the alternator has been keeping up.
 
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