Alternator upgrade

by builtnotbought Sat Aug 20, 2016 4:32 pm

I wonder if there is any alternator that is used on modern (90-2000) US cars that can be fitted to old sbc block brackets and wiring?
My stock alternator on idle when 2 air compressors are running goes down from 14v to 12v according to gauge.
May be somebody had any experience in upgrading stock alternator to more powerful unit.
What output does stock alternator have (in Amps)? I don't have any marks on mine. Modern cars have from about 140A.
Thank you

by Joe73 Sat Aug 20, 2016 5:20 pm

Loads of upgrades for our altenators. Its done all the time. Just google "chevy alternator si wiring harness". Plenty info out there.

by builtnotbought Sat Aug 20, 2016 5:25 pm

For now I found that 10/12si can easily be upgraded to cs-144 140A alt

and found theeese
http://www.dbelectrical.com/p-4516-high-output-chevy-3-wire-alternator-140-amp-65-85.aspx
Looks like 10si body with 140A output.

by bigredlaguna Sat Aug 20, 2016 5:46 pm

If I were going to get a 140 amp alternator, I would at least get it based on the 12si because of the better cooling fan.

by builtnotbought Sat Aug 20, 2016 6:18 pm

bigredlaguna wrote:If I were going to get a 140 amp alternator, I would at least get it based on the 12si because of the better cooling fan.

https://www.summitracing.com/int/parts/pwm-57294

10si body, 150A output on top and baffle like on 12si plastic fan

by dynchel Sat Aug 20, 2016 7:38 pm

I have a 105 amp alternator speced for a iroc z. (Sorry don't remember exact year) but the case is the sane. It fits when used as a one wire.

by fasrnur Sun Aug 21, 2016 1:38 pm

I too had one off of a Camaro dynchel on my V-8 S10. If memory serves me correctly it was off of an 86. Worked great and I'll probably use one on my Chevelle too.

by bigredlaguna Sun Aug 21, 2016 2:00 pm

builtnotbought wrote:https://www.summitracing.com/int/parts/pwm-57294

10si body, 150A output on top and baffle like on 12si plastic fan

This is actually a 12si case with a metal fan instead of the plastic one. This would be more reliable than the other one you picked because the case itself is designed to flow more air through the internal parts to prevent overheating.

Here is a good read about the differences.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

by builtnotbought Mon Aug 22, 2016 4:36 pm

bigredlaguna wrote:
builtnotbought wrote:https://www.summitracing.com/int/parts/pwm-57294

10si body, 150A output on top and baffle like on 12si plastic fan

This is actually a 12si case with a metal fan instead of the plastic one. This would be more reliable than the other one you picked because the case itself is designed to flow more air through the internal parts to prevent overheating.

Here is a good read about the differences.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

Thank you! I will read it!

by fasrnur Mon Aug 22, 2016 6:54 pm

Great read bigredlaguna. Thanks for sharing it.

by Hawk03 Mon Oct 12, 2020 7:47 pm

Since I've upgraded some electronics, I think it is time to install a new alternator to help with the additional load. I'll be installing a new battery too.

I would like to install a chrome alternator and need a little help ordering the correct one. I was looking at these:

https://www.jegs.com/i/Powermaster/713/17294/10002/-1?year=1977&make=CHEVROLET&model=MALIBU&submodel=CLASSIC+LANDAU&engine=V8+%28+5.7L+%2F+350+%29

https://www.jegs.com/i/Powermaster/713/17127/10002/-1?year=1977&make=CHEVROLET&model=MALIBU&submodel=CLASSIC+LANDAU&engine=V8+%28+5.7L+%2F+350+%29

https://www.jegs.com/i/Powermaster/713/37127/10002/-1?year=1977&make=CHEVROLET&model=MALIBU&submodel=CLASSIC+LANDAU&engine=V8+%28+5.7L+%2F+350+%29

Is there a better option? I would like a plug and play but I've read where some require to redo the plug that connects to it.

I read the article above but its still a little over my head so I'm not sure what I really need.

by REVINKEVIN / Mr. 600+HP Tue Oct 13, 2020 1:10 pm

There are actually a lot of options. This is my 300 amp alternator. I had to run a 0/2 wire to the battery and a 0/2 gauge ground. I know that you’re not going this far, but remember to run a larger wire to match the current output of your new alternator.

by Hawk03 Tue Oct 13, 2020 7:31 pm

Good call, thanks! I have the original wiring to the battery so its a good time to change that too.

by REVINKEVIN / Mr. 600+HP Tue Oct 13, 2020 8:38 pm

Depending on what amperage alternator that you choose, you might need a 10 gauge or 8 gauge to the battery. It is also a good time to upgrade your ground wire as well. Having good solid grounds is a must for a solid electrical foundation.

by Hawk03 Wed Oct 14, 2020 8:43 am

Good call. I think this 150 amp is probably good enough for me. https://www.summitracing.com/parts/pwm-37293/questionsanswers

I found this website that has reasonably priced cables so I will be ordering from there.

https://www.batterycablesusa.com/

What length are the factory ground cable and cable from the starter to battery?

by jerry46765 Sat Oct 17, 2020 10:25 pm

REVINKEVIN wrote:There are actually a lot of options. This is my 300 amp alternator. I had to run a 0/2 wire to the battery and a 0/2 gauge ground. I know that you’re not going this far, but remember to run a larger wire to match the current output of your new alternator.

Kevin -

What is the covering on your cables and what are those plastic things at the end of your ground cable? They are unique as I have never anything like that before. Do they plug into a circuit panel or some stereo?

Thanks -

Jerry

by REVINKEVIN / Mr. 600+HP Sun Oct 18, 2020 12:33 am

Hey Jerry. The battery connectors and fuse distribution are all from Stinger car audio. I have used their products a lot in the past. They make some good products. With all that’s going on power wise I needed not only the top post but the side post as well. The grounds are bolted to the frame with crimped copper lugs.

Hey Hawk, the 150 amp will work great in your car. Good luck.

by jerry46765 Sun Oct 18, 2020 8:58 pm

Kevin -

Stereo stuff, that explains why I have never seen anything like this. The last picture shows what appears to be a tee connection.

How are the wires connected to the tee?

And the insulator is the clear plastic?

There was one 150A bar fuse laying in the the first picture. How are these tees and junctions fused? It's appears adding wires could easily overload the feed wire. If you've done it before, you must know the loads or you would have smoke coming out by now. Pretty interesting but could be a fireball waiting to happen with the wrong guy.

Thanks -

Jerry

by REVINKEVIN / Mr. 600+HP Sun Oct 18, 2020 11:34 pm

Hey. Here’s a quick breakdown. The T and 2 fuse holders have an insulating back plate and a plastic bottom. They also have snap on thick plastic covers. The T is fed directly from the battery. 1 output goes directly into the 150 amp fuse holder. This feeds the 1200 watt rms sub amp. The second output goes to the MIDI 4 fuse distribution block. The green fuse feeds the 800x4 amp for the front and rear speakers. The other fuses feed the Holley HP fuel pump, duel electric fans, and the high current starter. The 300 amp alternator feeds into a dedicated cable with its own fuse inline. This is a 0 gauge wire. The T is fed in and out with 0/2 gauge welding lead. 0/2 welding lead is rated at 450 amps < 50’ In an unfortunate event, like a wreck, all of the fuses will short out and blow. This will protect everything behind them. Or so says DC theory. This is actually overkill for the actual max current draw for everything in the system working at FLA at the same time. In reality, the starter and amps will never be used at the same time. The amps have their own turn on circuit and only come on after another device is activated. What is not in the picture is the ground system. The block is grounded to the frame with 0/2 cable and the battery has the same setup. The rear of the engine is grounded to the body and the 2 amps in the rear ground to the frame with 0/2 cable. Doing all of this to a basket case car project is why I am also rewiring the entire car with a Painless Wiring Kit. I hope this brief description helps. Cheers.

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