Upgrading Blazer Alternator - Chevrolet Forum - Chevy Enthusiasts Forums

Upgrading Blazer Alternator

MTopper's Avatar
CF Junior Member

Join Date: May 2009
Posts: 53
Detroit Metro

January 7th, 2010, 9:26 PM   #1  
Upgrading Blazer Alternator

has anyone upgraded the alternator on their S10 Blazer? What kind did you buy, what amperage and so on... i am planning on upgrading my amplifiers and need more power output on top of the optima yellow top under the hood. i can run another battery but i'd rather not take up anymore space.

davtak's Avatar
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Join Date: Nov 2007
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Plainville. CT

January 11th, 2010, 9:22 PM   #2  
I have upgraded my alternator. It's a AD244 145amp alternator. Believe it's made for a Suburban, Escalade, Tahoe, etc. It'll bolt right up in the factory spot with the exception of the rear bolt won't fit. The only thing you have to get is a fan belt one inch longer than a stock blazer fan belt. I don't remember what the part # is, but you should be able to find out online. I had a stock alternator in my blazer and i have 6000K HID's, pioneer cd deck, and glow gauges and my stock alternator was struggling. My headlights were flickering and the gauges would dim when i used the turn signals. Now I have absolutely no issues at all. I did buy a ad244 alternator at a junkyard off of ebay and it had a bad bearing and sounded like a plane was taking off. I ended up using it for a core charge and bought a refurbished/new one at advance auto parts for 200 and it works like a charm. Here is the write up that I used to do mine.

How To: High Output AD244 Alternator for ~$80<!-- google_ad_section_end -->
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<!-- google_ad_section_start -->Here is a little write up/explanation on how to swap your stock CS130D alternator for an AD244 alternator off of most of the full size <nobr style="font-weight: normal; font-size: 100%; color: darkgreen;" id="itxt_nobr_2_0">trucks</nobr>.

For those of you that NEED a bigger alternator, weather it be because of <nobr style="font-weight: normal; font-size: 100%; color: darkgreen;" id="itxt_nobr_3_0">off-road</nobr> accessories (winches, lights, etc) or because you need the extra amperage due to a bigger sound system, you would probably upgrade to an aftermarket alternator to meet your needs. Well, unless you are paying $300+ for a built alternator with a good stator and regulator put in, you will loose voltage at idle when you purchase the upgraded one. This is where most people have their concern, especially you off-road guys.

For example, when you put a 160 amp stator in a stock CS130D (4.3L) case, you will get the 160 amps, but only at about 1000 engine RPM's. Our 4.3L's idle at ~550-600, so the output is a lot less, voltage and amperage. I've found that my "built" CS130D only put out 45 amps and 12.8v at idle, when I needed a LOT more than that to keep my lights from dimming at idle.

So, our goal here is to get output (amperage and voltage) at idle as well as our required output at speeds greater than idle. With the AD244, you can have the best of both worlds.

*You can pick up a used AD244 alternator from your local junkyard for ~$40-$50, depending on mileage/condition*

The AD244 alternator came off of several full size pickups, from different years. There were two versions of the alternator made, a 130A version and a 145A version. You can call your local junkyard/salvage yard and ask them what it came off of, how many miles are on it, and what version it is (130A or 145A). Here is a link to everything you need to know (including what <nobr style="font-weight: normal; font-size: 100%; color: darkgreen;" id="itxt_nobr_7_0">vehicles</nobr> it came off of) about the AD244 (thank juddspaintballs for the link)


*The AD244 alternator will bolt right up to the stock alternator bracket on the 4.3L with NO modifications to the bracket. The only thing that is different is that you won't be using the 3rd bolt that is on the backside of the alternator. The CS130D has this, but the AD244 doesn't. You won't have any troubles with the bolt not being there.*

*The AD244 uses the same wire harness as the CS130D. It is a plug-and-play application.*

Now, I know what you guys are thinking..... "well dude, I need wayy more than 145 amps." That's what I was thinking too when I was doing this mod. I've got a decent sized sound system in the truck and some aftermarket fog <nobr style="font-weight: normal; font-size: 100%; color: darkgreen;" id="itxt_nobr_8_0">lights</nobr> on my safari bar, so I needed the extra amperage.

Bench tests have proven this alternator to put out 200+ amps at idle when cold. Yes, that's right, at idle.

When the alternator is warm it will easily put out 100 amps at idle,which is way better than the CS130D which is only capable of producing ~40 amps at idle.

It is a slightly underrated alternator (you audio guru's out there know what the term 'underrated' means and how it compares to the quality of a product). I can crank my system to the max and have no voltage issues with it when I'm at idle. I'll maintain a 14v and my lights don't dim.


Now that you have the alternator, you'll be needing a longer belt. I can't say how long of a belt you'll be needing, but the stock one won't work. If you DO get the stock belt to work (some have) I STRONGLY don't recommend it. It will put a bigger strain on the bearings in the alternator and can cause premature failure. It's worth the extra $35 for a new belt.

*You will need a belt that is 1"-1.5" longer than stock. For some reason, the lengths of belts changed from year to year (even 98+) so you'll have to do a little bit of math and figure it out on your own *


I also highly recommend doing the "Big 3" upgrade when doing the AD244 mod. Stock wiring CAN take the 200+amps that the AD244 puts out, but if you are having problems with it, then it is probably the wiring.


Here are some pictures of my AD244 in action:

Output at idle with just my headlights on:

Output at IDLE with my system cranked to the max:

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Output at IDLE with all accessories on (all 4 headlights [quad beam mod], a/c on MAX with fans at #3, fog lights, and my system cranked to the max:

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13.96 can be lower than most would like to be.... but a stock CS130D would be gasping for air if I was treating it like that.

So, if I had things my way, every s10/blazer would have an AD244 as their alternator, even if they have a stock electrical system.

MTopper's Avatar
CF Junior Member

Join Date: May 2009
Posts: 53
Detroit Metro

January 18th, 2010, 10:47 PM   #3  
thanks a lot for the help. i will be doing that shortly, what was happening to me was my volts dipped really low when i had my radio turned up to 3/4 and my sub was going. If this fixes it i'll be one happy 20 year old haha. thanks again Davtak

Stormin' Norvin's Avatar
CF Beginner

Join Date: Dec 2015
Posts: 1

December 25th, 2015, 1:34 AM   #4  
I found this forum thread and upgraded the alternator in my 2004 Chevrolet Blazer LS 4X4 to this (mine came with a brass-colored pulley)...

Ultima Select 391611 - Alternator | O'Reilly Auto Parts

The pulley size is the same as the OEM one, but the case is bigger so the pulley location moves up and out so a 1" longer serpentine belt is needed. This one worked perfectly...

MasterPro Belt/Hose K060962 - Serpentine Belt | O'Reilly Auto Parts

So far everything is working quite well.

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