Alternator choice - Team Camaro Tech
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post #1 of 8 (permalink) Old May 10th, 11, 09:24 AM Thread Starter
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Alternator choice

Is there any reason not to upgrade a 10si to a 12si alternator? I'm not working on a numbers matching car.

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post #2 of 8 (permalink) Old May 10th, 11, 02:00 PM
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Re: Alternator choice

I don't care for the plastic fan, but otherwise, not an issue as long as your wiring can handle whatever current capacity you choose.
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post #3 of 8 (permalink) Old May 10th, 11, 05:09 PM
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Re: Alternator choice

Nope! There a few good reasons to make the upgrade like better cooling and higher output in stock form. Check out this article:

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post #4 of 8 (permalink) Old May 10th, 11, 07:14 PM Thread Starter
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Re: Alternator choice

Thanks for the suggestions. The wiring is stock so how much would you guess it can handle? I was thinking around a 100 amps.
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post #5 of 8 (permalink) Old May 10th, 11, 08:18 PM
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Re: Alternator choice

110A one wire 10SI form DB Electrical here, chrome for $61. Stock wiring is only 10AWG so it can support 30A max continuous but your fusible link protects it. Alternators are demand driven....they'll only put out as much current as you require while maintaining voltage level. I personally have an auto reset circuit breaker in place of the fusible link. Then I've got another 80A fused cable feeding a couple small fuse blocks that any non-original device is supplied from (OK, the HEI and EFI ECM still come off the stock fuse block).

Anyway, with an HEI, high pressure EFI pump, a few other devices, etc. etc. I get 14.4V steady at idle. Those models put out 65A at 600 RPM and full current at 1200 RPM and they put the big fan on them.

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post #6 of 8 (permalink) Old May 11th, 11, 07:06 AM
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Re: Alternator choice

The big fan is for big cooling. I run the 12-SI and it's been the most dependable alternator I've ever installed.

I tried the CS alternators (even the w/Iceberg), but haven't had much luck. I tried 3 and all 3 failed. If your battery goes down or there's a voltage spike they seem to take it bad and fail. They seem to be fragile and failure prone.

The 12-SI could care less and just keeps chugging along producing lots of power reliably.

You should upgrade your wiring to the horn relay and take fusible link precautions like Steiner says.
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post #7 of 8 (permalink) Old May 11th, 11, 01:57 PM
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Re: Alternator choice

I went with a CS130 (105 Amp) which needed a few wiring tweaks.
It's for a 89 Pontiac Safari station wagon...stock looking fan and V-pulley.

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post #8 of 8 (permalink) Old May 12th, 11, 12:53 PM
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Re: Alternator choice

I got my 12si from Autozone. 78amps is enough and I have an electric fan and water pump. About $50 with a lifetime warranty. I'd also recommend a 3 wire setup over a 1 wire deal, especially if you have an electric fan.

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