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Dual alts? (Brain puke)


McWillies

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I have a custom 170amp 3g alternator on the way and I've just been toying around with the idea of dual alternators (2.9), in my head. Not really planning to actually do it, but the idea is interesting.

On 2.9s with a smog pump, the bracket on the passenger side for the alternator was slightly different, to mount the pump underneath it.



If you've ever pulled that bracket off, you probably recognize the diagram, but most of the 2.9s didn't come with a smog pump from what I understand, so that part may seem foreign... It does to me at least. Another weird thing you might notice is the alternator front cover has mounting points 180 degrees apart (maybe a slight difference on models with a smog pump?). My 2.9 takes an alt with a 2 o'clock adjusting ear.
The pivot mount on top of the smog pump is very similar to the pivot mount on the bottom of the alternator, but the alternator one is slightly thicker (front-to-back) I believe. This shouldn't be a major setback because the mounting tabs on the bracket have quite a bit of thickness to them, so shaving it a quarter inch or so, to open up the gap between the two mounts, would be fine structurally. Making sure the bottom alt pulley is in line with the others may be a bit tricky, though.

Looking back at a picture of the bracket on my engine, It looks like there aren't holes drilled on the two mounting tabs. Here's a good picture of one that I found:











The bracket is upside down from how it would be mounted, but this is the rear mounting tab, with no hole drilled.







Here's the front one, same story. You can see the flanges are pretty thick though.






You can also see the tabs are offset quite a bit horizontally from the alternator lower mount. This isn't a bad thing in my opinion as I'd probably wanna run the two alts on different belts; that way I don't lose both alts if one belt fails. Obviously the alternator front housing would have to be clocked so that the swivel is on top, but that shouldn't be a problem. As for the second mounting point, something very similar to the original alternator mounting could be used, but the hole wouldn't have to be oblonged because the belt can be tensioned elsewhere.

This is just my brain running through different things. Let me know what y'all think, thanks.
 


wildbill23c

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What could you possibly need that much alternator output in a Bronco 2 for? I have a 90amp in my 88 Bronco 2 and its more than plenty...dual alternators don't do much if you don't have the electrical load and batteries to support it. Maybe a 2nd alternator in the place of the AC compressor if you don't have AC or no longer need/want it...I'd rather have the AC, these things are like ovens in the summer without AC.

I thought about dual batteries but there's no place to put a 2nd battery under the hood so I didn't bother with anything else just a higher output alternator from when I thought about using my Bronco 2 as a mobile Amateur Radio rig, but don't really have any interest in that anymore either so the higher amp alternator really doesn't do anything so I'll be going back to a standard output when this one dies.
 

JerryC

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The test sheet from my 95 amp alt says it makes 49 at 1600. Doesn't say what it makes at 900 (idle) but going from memory I think I tested it at real close to 40 give or take.
Lights eat up a good chunk. Performance halogens are about 5-6 amps each, the rest of lights are around 5 if include brake lights and dash lights. The blower motor I think I measured somewhere around 12 amps at full speed.
That's ~27 amps, now in my case add an E-fan that draws 19 more... Maybe 2-4 four more radio and I'm past what my alt does at idle.
If I had a killer stereo with some big amplifiers and some off-road lights my alt is way behind. The problem is that getting a v-belt to drive a stronger alt becomes problematic, or so i have read. Switching to serpentine might be answer as well as dual v-belt if you can make that work.

I put LED headlights in to lower the amp draw and get much better lighting and I think at idle at night with AC full blast and E-fan on, the alt is right at the edge of breaking even. Good news is that at night I don't have to run the blower at full speed once the cabin cools down as there's no sun to heat it up.

I remember with my 45 amp alt the old halogen lights would dim noticeably at idle.
 

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