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Discussion Starter · #1 ·
I am going to upgrade the electrical system on my car to accomodate electric fans. The fans are going in because of the A/C upgrade I am now finishing up. As I read about this stuff I am getting confused can someone help me clarify terms?

Anybody here rebuilt one of the lower output stock GM external regualtor alternators to produce higher output? This is my preferred path since I HATE messing with electrical stuff but i gotta do this alt. upgrade because of the fans. Loading in a 100 AMP GM made external regulator seems like the path of least resistance (no pun intended). I am reading up on this subject and it appears that it can be done failry cheaply thereby eliminating all the issues of doing wiring mods to get to a one wire system. Anybody done the rebuild? What was involved and what did it take to do the actual conversion?

A couple of General questions:

CS is an AFTERMARKET alternator...right? Is it a one wire alternator or is it a 3 wire. If I were to go to a CS alternator what is involved...just a change of a connector at the alternator and no other wire mods????

SI is the one wire integrated GM alternator right???? If I go with one of those I eliminate my regulator and run a heavier guage wire from the alternator up to the horn relay. If I do that what happens to the old wires that went to the reguator and any other locations????

Thanks for your help.
 

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“Loading in a 100 AMP GM made external regulator seems like the path of least resistance (no pun intended). I am reading up on this subject and it appears that it can be done failry cheaply thereby eliminating all the issues of doing wiring mods to get to a one wire system.”

Well you perhaps have a 37 amp alternator and are looking to squeeze 100 amps out of it. Not sure it can be done as cheap as replacing it out. Personally I can’t see the advantage of running a one-wire in a Chevelle when it’s almost as easy to run a 3-wire and maintain decent regulation. The mod for wiring an external to an internal involves changing a 2 wire connector and tying 2 other wires together (or buying a shorting block.)

“CS is an AFTERMARKET alternator...right?”

Nope just a different type. Believe it stands for Constant Sensing but could be wrong. CS alternators were used in later GM cars.

“Is it a one wire alternator or is it a 3 wire.”

Can be either. GM ran them as a 3-wire. Some of the aftermarket units can be run as a 1-wire or a 3-wire.

“If I were to go to a CS alternator what is involved...just a change of a connector at the alternator and no other wire mods????”

The connector, and jumping two other wires together. No matter which way you go the red wire on the rear B+ terminal will be too small and will need to be upgraded.

“SI is the one wire integrated GM alternator right????”

Nope, it’s an internally regulated alternator but it’s a 3 wire. Two wires in the plug and 1 on the rear.

“If I go with one of those I eliminate my regulator and run a heavier guage wire from the alternator up to the horn relay. If I do that what happens to the old wires that went to the reguator and any other locations????”

Ever looked at Wes Vann’s instructions?
http://www.chevelles.com/techref/ftecref14.html
 

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Discussion Starter · #3 ·
"Well you perhaps have a 37 amp alternator and are looking to squeeze 100 amps out of it." I bet it is 37 since the car originally had very few accessories. I agree likely I can't there from here if it is 37 Amp.

"Personally I can’t see the advantage of running a one-wire in a Chevelle when it’s almost as easy to run a 3-wire and maintain decent regulation" I sure agree with that. But then when you read the MAD website they say if ya use their kits you get proper regulation. This is why I hate this electronics stuff. First of all I don't really understand it and second of all one mistake and poof something is fried or the car burns down. I just want a 100 amp alternator. I can live with the external regulator and would like to keep it if I can. If all I have to do is replace existing wires with heavier wires well that sounds OK to me. I just really don't want to be removing wires and reconnecting things to different places...just gives me the creeps.

"Nope, it’s an internally regulated alternator but it’s a 3 wire. Two wires in the plug and 1 on the rear" So the CS is a constant sensing, 3 wire internally regulated alternator???? Ok that is new news ....I think. Seems I read someplace that the CS alternators are harder to get parts for and they have a spotty perf history?????

"Ever looked at Wes Vann’s instructions.....?"
Yes but I guess I missed something. Some of the info here means I gotta reread what Wes posted.

I guess the short version here: modified after I realized that I might have a lowly 37 amp alternator is...."How do I get to 100 amps with a GM alternator that bolts into my existing brackets (this is a MUST because of some special stuff on the car. I cannot go rebuilding and redesigning new brackets) with a minimum of rewiring and what is that minimum of rewiring." Even if I gotta buy a new alternator well that is not the worst that could happen.

Any help on this seconf set of questions would be greatly appreciated.
 

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“I sure agree with that. But then when you read the MAD website they say if ya use their kits you get proper regulation.”

MAD doesn’t sell regulator kits to the best of my knowledge. Maybe I’m wrong. If you have been over there the article written about one-wire versus three-wire is worth reading.

A little more pricey way of doing the external/internal conversion is to get a kit from M & H. Less wiring and may make it easier for you. Part number is 27555 and somewhere around $13.00.
www.wiringharness.com

"Nope, it’s an internally regulated alternator but it’s a 3 wire. Two wires in the plug and 1 on the rear" So the CS is a constant sensing, 3 wire internally regulated alternator???? Ok that is new news ....I think. Seems I read someplace that the CS alternators are harder to get parts for and they have a spotty perf history?????"

I actually prefer the 12 SI type of alternator over the CS. 94 amp models can be found in junkyards around here.

“I guess the short version here: modified after I realized that I might have a lowly 37 amp alternator is...."How do I get to 100 amps with a GM alternator that bolts into my existing brackets (this is a MUST because of some special stuff on the car. I cannot go rebuilding and redesigning new brackets) with a minimum of rewiring and what is that minimum of rewiring." Even if I gotta buy a new alternator well that is not the worst that could happen.”

Doesn’t the MAD site list GM alternators, in a table, with their output ratings? Your external regulated alternator uses the same case as the SI.
The M & H kit comes with a plug that takes the place of the regulator. No wire moving.
The M & H kit has the connector for the internally regulated alternator. Cut off the existing alternator connector and replace with new connector (2 wires).
Larger wire on the alternator output.---Done.
Your car. I only point out options and an opinion.
 

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Discussion Starter · #5 ·
Good stuff John thank you.

I am going to think a little about this but the SI 94 Amp sounds like the ticket as I read more. Now the only question I have is why does MAD want ya to change to heavier wires and run a new distrib block on the Firewall when the other guys you mentioned say you only need a simple jumper wire gadget like P/N 27555.

I think I like the MAD approach better cause it involves heavier wires but I am learning and i appreciate you help. Keep it coming.
 

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why M.A.D. doesn't want you changing wire size's is that the voltage rate depends on part to the size & resistance of the wire your using .... Mark the owner of Mad is a great guy very helpfull & has YEARS & YEARS of experence with our favorite cars .. you'll be hard pressed to inprove on what his kits include ...just visit Mad's web site theres more info there then MOST of rest of the after marker industry put togather ... & IT's there to help the little guy understand he's cars system ... MY 2 cents & yes I've bought lots of stuff from MAD ... no I don't own stock
 

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Discussion Starter · #7 ·
Might be your misreading what I am saying or perhaps you made a typo. MAD does want ya to add heavier wires. I think they want #8 added in a couple of places.
 

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OH...... I thought you were talking about changing MADs set up it is how the voltage is regulated to the battery ...... if your following the wire sizes from print off the web site you're doing fine
 

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The alternator wire origionally connected to the horn relay. You really only need a heavier wire from the alternator to the power point where the fans are connected. So, run a heavy wire to the horn relay and then connect the fans there. Or run a heavy wire to a new terminal block and then run the fans from there and a jumper to the horn relay.

The 12SI alternators are a good choice and they look and fit much like the origional except for the plastic fan. The CS type can supply a little extra current at idle and they can also be installed with little or no bracket modification. They do seem more prone to failure though from listening to different sources.

Either way, connect with the M&H kit or follow the tech reference for wiring. Personally, I pulled back the tape on my harness and removed the extra wiring and regulator connector by running the brown wire that went to the regulator directly to the alternator.

If wiring really bothers you then look for an aftermarket 1-wire alternator. You can get a 1-wire with very good current ratings. Just remember, you probably won't find one in a local parts store if it acts up on you somewhere. I also wouldn't recommend a chrome one since the chrome holds the heat in and that thing will be producing a fair bit of heat running the fans at night with the lights on.

Peter
 

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Originally posted by oman:
Good stuff John thank you.

I am going to think a little about this but the SI 94 Amp sounds like the ticket as I read more. Now the only question I have is why does MAD want ya to change to heavier wires and run a new distrib block on the Firewall when the other guys you mentioned say you only need a simple jumper wire gadget like P/N 27555.

I think I like the MAD approach better cause it involves heavier wires but I am learning and i appreciate you help. Keep it coming.
If you re-read my post above I mentioned you need to do both things. Change the connector out and larger wire on the alternator output. No need for a new distribution block. Won't change a thing.
 

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In order to affectively upgrade your altenator for higher amps, you would need A NEW Stator and Rectifier assembly rated for the higher current. The voltage regulator shouldn't need changed since all it does is control excitation current to the rotor to control alternator output voltage, It is not affected by current it only senses output voltage. 10DN, 10SI, 12 SI, and CS are all alternator case styles, CS alternators are used on newer cars as it allows for better cooling for high amp alternators.
 
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