lrios

So I'm thinking about adding a second alternator to my Cutlass. I was thinking about placing it where the AC was originally mounted. Has anyone done this? I understand I could just get a larger alternator but the 105 amp alt in my car is brand new and would be cheaper to add a second 105 amp than it would to get a 200+ amp alternator. Thoughts anyone?

Olds64

Why do you want 2 alternators?

lrios

Amplifiers with a combined wattage of 3300 rms

Olds64

If you could make a custom bracket there's no reason you couldn't add a 2nd alternator.

lrios

Weren't the non AC cars designed with the alternator on the passenger side? I was planning to use a bracket from one of those.

Olds64

What year Cutlass is it and what engine does it have?

lrios

It's a '69 supreme with a 350

joe_padavano

Trucks set up for emergency vehicles routinely have dual alternators. Why you would want to do that for your application is a mystery. Can you do it? Sure. Is it the best way to go? Unlikely.

Olds64

Check it out!

https://alternatorparts.com/

droldsmorland

Ya, I was gonna suggest a single high output alternator. You will need to upgrade wiring to handle it.

Schurkey

Two alternators may end up fighting each other for voltage control.

If this was me, I'd shitcan the power-hungry amplifier. There's zero reason for an automotive amplifier to need that much power unless you're deaf, or trying to be deaf.

cfair

Sounds like you need to sum up the amperage demand for the whole car running (lights, heater, A/C, engine, etc) plus any aftermarket stereo to establish what the max amperage draw is, then look at either 1 or 2 alternators. Joe’s right about 2 alts. Last Fall I saw a ‘66 98 Ambulance with an alt so big they had to slice into the hood support to make room. 1966 technology...

If I remember right I’m running a 105 amp 12SI alternator for two amplifiers - 1 for the sub, 1 for the 4 corners. The electrical system is solid and doesn’t run down the battery (Optima AGM). It’s a bit of a trick fitting the later alternator into the mid 60’s big cars, but it’s more than doable. I’ve done it twice or three times. The slightly larger later alternators just need a different sized belt and maybe a slightly longer bolt in the intake manifold with some washers to make a spacer for the larger diameter case.

Initially my convertible was delivered with the alternator by the power steering pump. When I removed the smog air pump, I moved it to the passenger side to equalize the physical load on the water pump pulley. Hell, I even ran a Toro alternator bracket for 5 or 10 years since I liked the low slung positioning. Point is, you have lots of options here. I’d stay as close to factory as possible to ensure longevity.

The other major mods were running the “Sense” wire to the Olds junction block on the driver’s inner and not jumping it across the 2 leads at the alt. Also I put an 8ga or 10ga output wire from the 12SI to the junction block to minimize heat and maximize throughput. Wire size was maybe overkill, but better too big, than an electrical fire. I had the harness stripped to locate the sense wire so it was easy to add a fat output wire.

Long story short I’ve never needed 2 alternators even with 2 amps, head unit and speakers spread all around. If you can’t figure out the power budget, I’d start at a 140 amp 10SI or 12SI for simplicity and see how it goes.

Hope the car winds up sounding great!

Cheers
cf

OLE442

Back in the day, my son had a 1990's Caprice Wagon(with wood grain on the side) with the de-tuned LTI engine in it and was into big speakers and big "thump"! He added a second alternator and another separate battery in the backl. He had it all wired up with this colored clear humongus cable set. He said, "I now have the ability to jump start my own car"...LOL! He had some gigantic speakers in the back! Not my thing but he did do a neat job on it. He also learned a lot about electronics and working on cars(that's what my wife kept telling me) LOL! I'm pretty sure he bought the mounts for it off the internet.

oddball

Running multiple alternators is quite common in the audio world. They all play nicely with each other, assuming the voltage references are actually connected (internal is just fine, but best to use a single external reference for all the units).

Are you getting voltage sags currently? Granted, I'm not an SPL guy, but my 2,000 watt amp never pulls more than 2 amps.

There's no multi-alt mount for Olds. If you don't have A/C, then you can use both the driver mount and passenger mount brackets along with the 3 row pump and crank pulleys. Post a parts wanted ad for whichever you need. You'll need to make/use spacers on the passenger side to push the alternator forward to use the A/C belt location.

If you DO have A/C, then you're looking at doing something custom or getting a really beefy alt.

Depending on how much amperage you really need, the Powermaster 150 amp units are nice little beasts.