Mac - the max current draw for the accessories is known, look at the fuses.

Sam - incoming pm. Remember we aren't looking for total current, we are looking for idle current output. The only way to know that is physically test it or lookup the manufacturers data. Your alternator puts out enough current (rotor/stator combo) but fails under time (diodes heat up). Either the diodes aren't mounted well to the case, the case has insufficient mass and/or airflow to cool them, or the diodes are just overworked (too small for the application).

Random FYI - you can increase the alternator speed by getting a smaller pulley on it. This has to be done somewhat carefully though - you have to know your engine redline and consider the max rpm the alt can take before it kablewys itself.

If I recall correctly, the pulley on this alternator came off the Mopar unit and was re-intalledby a machine shop on the present alternator. It looks to me as if the fan on the present alternator is on backwards. Shouldn't the vanes be pointed in a direction that would catch or scoop the air and draw it into the unit? Clockwise rotation will not do this on this unit. This would be the work of the machine shop, perhaps, or maybe the rebuilder NAPA sourced it from. This came from NAPA about 10 or so years ago.

Since idle output is what is important, maybe going with the known new unit from the source you linked us to is the smartest idea. That and making sure the fan is on right.

For what it is worth, my BMW has a small air scoop that delivers cool, before the radiator, air to the alternator. Some say they over think their designs, but under thinking can be a problem as well. It would be really simple to get up front air to the alternator. I will think about that. This almost makes me think getting the alternator fanned turned around might be a cheap first step. Then get some cool air to it.

Sam

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I'm not sure about that method. My 68 Dart fuses and breakers total 108 amps. By that measure, it would seem that I need a 135 amp alternator for my car, but I would bet that a good 65 amp unit would more than handle the load. Fuses are rated to prevent smoking wires, they are not necessarily a great indication of normal current draw.

I'm just trying to say that you might not need a massive, 250+ amp alternator to do this job... it's entirely possible that a well functioning, smaller alternator might be better suited for the load.

The current measurements should give you the parameters you need to make an educated choice.

All that said, this unit claims to put out high current at idle speeds, though I have not researched it in the least:

http://www.youtube.com/watch?v=Mz99hT6jalc

- Mac

I said max current draw, not avg. If he can satisfy max current draw you wouldn't need much of a safety margin.

I didn't say he needs a monsterous alt... But generally speaking the beefier units are better built and will handle more heat. I just wanted to ID the new alt he has to make sure it's sufficient before he goes through the hassle of installing it only to be disappointed.

Sam I wouldn't hassle with trying to get it more air. That's only a bandaid to the problem.

In looking over the web pictures on the link Pierre posted, maybe I am wrong about the direction of the vanes on the alternator fan. At least one of them had the vanes pictured leaning to the left instead of the right. Do these things ever turn counter-clockwise? I do not see how that could be possible.

Could they maybe have the photo flipped around? How can a fan draw in cooling air if the vane point to in a counterclockwise direction?

Sam

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Vanes are to fling air out, pulling air from center of alternator.

So they fall back from the direction of rotation.


Alternators will produce the same output in either rotation direction. The vanes are set up for the application (serpentine belt drives may be opposite rotation to the rest of the engine)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Then these are probably OK. I am learning a lot this go-round.

Sam

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Sam,

I was expecting pics of the alternator you were considering buying from your friend, whoopsy.

The pics you sent appear to be of a 12si. Oldskewl. Stock, there are different versions (of current output) apparently. If its one of the higher ones and is well built you should be ok. The one you have may not qualify. The good news - it shares the bottom 2" mounting ear so changing to a more modern CS144 should be relatively straight forward. Believe the span from top to bottom bolt is different so the upper swing arm may need some tweaking.

In looking at Quality power's web page, on the high output section, there are lots of options available. It looks as if they can mix and match features to your specs. Two questions:

1. What combination of features would I ask for on the custom, high output units? Obviously I want a V belt, and I guess the 150 amp unit would be OK.

2. Do they sell a GM standard unit that would still work and be cheaper? Would a stock cs144 be the ticket now?

What should I ask for when I call? I still need to check out this other option from one of our forum members who is away until this weekend. This is unusual for me to be patient like this. I usually go out and buy, and then ask questions later.

The upper brace configuration is not a concern. I can work that out.

Sam

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I see absolutely no reason for an alternator with that high output. My EFI and elec fan cars do just fine with a 45 amp super mini alternator, or a stock type 40A. Granted, you have more to run, but not 3X more. I would be looking for a 80A or so, which should be plenty and will be easier on wiring. More wt, more bulk, etc are always bad IMHO.

Just my 2 cents...

Lou

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Home of Slant6-powered fun machines since 1988

You think the voltage is dropping because of a faulty alternator?
Sam

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40a stock alt with efi??? They can barely keep up stock for stock, not sure how you got away with efi and electric fans on one. Again guys the point of a hipo unit isn't necessarily for the current but rather more stout components. He's not building a race car... The more mass the case has the more heat it will absorb from the diodes.

Sam, a stock 140a cs144 otta do you fine. I know it may be frowned upon... But so far my parts store new unit is doing ok and cost less then 150. If you want to spend more you can go directly to the aftermarket new ones.

Serpentine and v belt pulleys are both available. If you must use v belt getting two on there would be better then 1. When I was running v belts I recall having accelerated belt wear On a belt that long to passenger side.

So if I go to NAPA they will need an application. Is that the 95 Comaro mentioned earlier? Will they be able to reference an alternator model number?

Sam

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They probably can't do anything if you tell them cs144 but yes I you give them 95 chevy camaro or cadillac Seville 4.6l that should get you a 140a cs144 with 12/6 o'clock ears. If they ask heated windshield say no. Get the harness connector while your at it. You'll need an indicator light and/or resistor to emulate the original oem circuit as well ... I can dig up the details on that later.

How would I k now if what I got ws a CS144? Would the box or the case say that?

I have a standard relay coil wired in series on the voltage reference line. It looks weird just hanging there on the fender beside the alternator, but it does the job. It would be nice to have something just a little more elegant in the circuit. I never knew what size resister to get.

How does the light in the reference circuit work as an indicator? What information would it provide the driver? Are there times when it would, or would not light, and what would that indicate? Thanks again.

How about this unit? It seems like by the time I get the pulley changed I am better off buying the new one from Quality Power.

http://www.usautoparts.net/catalog/?N=9 ... 11921+9176

Or the bottom one here http://www.usautoparts.net/catalog/?N=9 ... 11921+9176

But by then I am up to the price of Quality Power's unit.


Sam

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