High output alternator

[gmachinz]

Time for a CS alternator conversion and an HD charging system upgrade.

 

[1973c10]

Time for a CS alternator conversion and an HD charging system upgrade.

Why's that ??

 

[Snoots]

This is why I think I am pulling to many amps
My current alternator is 65 amps
I have 2 Electric Cooling Fans 15 amps each ( 30 amps total )
halogen headlight 18 amps
Instrument Panel 2 amps
Lamps, License Plate 1 amps
Lamps, Side Marker 3 amps
Lamps, Tail 5 amps
CD/Tuner with Amp 40 amps
Ignition 10 amps
Electric Fuel Pump 6 amps
plus thing I don't run all the time like AC , Heater Defroster , Dome Light , Back-Up Lamps and so on

I believe you've answered your own question.

 

[MikeB]

I think a 12SI, or modified version of it, is a great way to go. In stock form there are various ratings, with the highest being 94 amps. Don't even think about buying a 100+ amp aftermarket alternator using the 10SI case, because its cooling is nowhere near as good as on the 12SI. I put a a rebuilt AC Delco 12SI in my 69 C10 almost 20 years ago and it's still going strong.

I have no experience with the CS alternators, but I have read on various forums that they are not as reliable as the 12SI. Don't take that to the bank, though!

Some good general info on alternators here:

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

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

 

[AuroraGirl]

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Any easy way to tell if I got a 12 si or are these all 10?

 

[75gmck25]

Take a look at this article, and I think you'll find you have all 10si alternators. http://www.madelectrical.com/electricaltech/delcoremy.shtml

FYI - If you go into a parts store with the right car description (for one with a 12si), you can get a rebuilt 12si for a decent price and use one of your 10si alternators for a core. The stores don't seem to care if they are exactly the same.

Bruce

 

[Catbox]

We have recently put a 12SI 94 amp model under the hood of my truck.
Easy peasy and it works like a champ.

 

[AuroraGirl]

We have recently put a 12SI 94 amp model under the hood of my truck.
Easy peasy and it works like a champ.

Do you run any equipment that are harsh, such as a snow plow? I read that 12si makes more juice in the low RPM range and was hoping I had a shelf one. It appears not, but that's okay! I was gonna have a 12si rewound if I had it for free, but I got to buy one so I will just get a good amperage probably.

Context: at idle I have 11.19 volts almost constant with periodic spikes and dips

 

[Itali83]

So you guys with the 12si alternator, which application did you use for a bolt in conversion? Also, are you still using the single V-belt drive pulley? If so, does it squeal at all? We all know that the old school v-belts like to squeal under load and I’m wondering if a higher output alternator will squeal the belt.

ben

 

[jake wells]

If you are going to be running that kind of set up i recommend the big 3 or 4 set up. That and replacing chassis / body ground straps with #4 welding cable.

Replacing some of wiring with heavy gauge wire will help with voltage sag and provide better starting and charging as well.
@HotRodPC do you remember this mod i think you posted it a number of years ago?

 

[Itali83]

I’ve already done the wiring upgrades. 4ga cable from alternator to battery. 4ga ground from body to frame, frame to battery, frame to motor. I haven’t done the headlight relay set up yet but I’ve got a tired alternator and want to upgrade.
Ben

 

[gmachinz]

Dimming lights and such have more to do with the method in which GM opted to take shortcuts to route power in these factory style harnesses which Painless and others just copy with no regards for upgrading the system for modern conveniences.

CS alternators have a faster acting regulator window time that any SI alternator which means voltage recovers nearly instantly whenever a component is turned on.
And regarding amp draw, you dont need to assume the max fuse ratings @100% when picking an alternator-I suggest taking 70% of your max amp total amd using that to gauge what size alternator to use. Modern vehicles use wayyy more juice than even what you’re consuming but there arent 4ga grounds and power cables running all over the place. You don’t need electric fans running at 100% fan speed every time they’re on-run a damn variable speed controller or use a multi-step resistor harness setup. A 40A rated CD/amp setup doesnt mean it runs at 40A constantly...etc. Those are max ratings, not nominal-think of it like an amplifier-it may say 1000W but how often are you constantly pushing it at 1000W?

After all that consideration, upgrade (ie modernize) the charging system to at least up to 21st century wiring standards...it will really make a big difference in the end-GM took shortcuts on power distribution and companies like Painless don’t do much to improve it.

 

[C10MixMaster]

So you guys with the 12si alternator, which application did you use for a bolt in conversion? Also, are you still using the single V-belt drive pulley? If so, does it squeal at all? We all know that the old school v-belts like to squeal under load and I’m wondering if a higher output alternator will squeal the belt.

ben

not sure what mine came from its the one upgrade the previous owner did right. I can tell you it works fine with a single pulley no squealing .