Motorcraft alternator upgrade

They may be rated 500 watt, but I highly doubt they pull a continuous 500 watts......
If that were the true pull, just to run the power wire to the unit a distance of only 7 feet would require #8 wire - possibly a #6 if the run wasn't direct.
42 amps out of an alternator at idle would be a notable load on the engine, then kick on the A/C compressor and ouch.

One may be interested in hearing that the test specs state that (in most cases, most manufacturers) if the alternator puts out within 10% of the rated output it's good.
I have to wonder, and may try to find one to test for kicks - if a 130 amp alternator will actually even do that - and if so, continuously? Or is that a peak rating? And if it did, and it was in specs, then it may actually only put out 117 and be called just fine by the maker. So a 60 in perfect working order according to the manufacturer specs may put out 54 and be just fine, and not covered as "not putting out rated output".

Windows, locks, etc. are non-continuous and normally not counted at full ratings for charging system output.
You aren't using all accessories at one point in time. When is the stereo (rated 500, but won't really be pulling that much even in the worst cases) and the power lock solenoid and power window motor and sun roof motor, etc. etc etc all used at one time?

My shop has a 100 amp box - and yet if you add up my powder coating oven, welder, the HID lighting, the fluorescent lights upstairs, my 220v 5hp air compressor, 2 ceiling fans, vacuums, RAS, table saw, sanders, power miter saw, belt sander, scroll saw, band saw, car battery chargers, drill battery chargers, exhaust fan (let's see, what did I leave out - oh, yeah) soldering gun(s), infrared heater fan..... I suspect I'd be blowing 100 amps away really fast and burn the place down.

honestly,  I ran a 60 in my truck in the stereo contests with all the power stuff, and all the heavy lighting that would give you a sun tan at night, did fine.
The Jeep I pulled the engine from for my Eagle was loaded, premium sound and bells and whistles like you'd expect in a ZJ - 60 amp alternator.

I know where the myths about needing 120+ amp alternators when upgrading comes from. but the gap between the number as far as what's really needed vs. the number arrived at by adding up power accessory ratings is pretty large sometimes.

One good way to tell is to check the wiring. If the wiring can support that sort of load, then the load is closer to reality. The big alternator doesn't mean the thing really needs it. They are standardizing more and more.

Since I have to support and back what I work on  or sell someone, I'm not about to tell them a 37 is fine if I have even a hint that they might burn it out with a 70 amp load in the first month. That may well be another reason for 130+ amp units on a car that will never pull that much load..... WARRANTY, hassles.

(It would indeed be interesting to really see the wire gauge run on some of the high rated units, and what they run from the alternator output back to the loads.......)

Just tossing out thoughts- that's all. 




Edited by billd - May/29/2012 at 2:57pm

Put the a/c on this winter?!?!?!

kellysguy wrote: Put the a/c on this winter?!?!?!   It aint cold enough in Ohio already?   It does look nica and clean. Looks like someone has a mill for a toy   The GM 63 amp 7127 is still readily avalible over-the-counter not only in stock form but one-wire too.

I'd do it sooner if I had time but I'd rather be driving it!

Been in the mid 90's here so not to cold.

Thank you. No mill, just a press as I posted in another reply but you don't have to bend them if you can't. The vise did work OK but it didn't bend quite as nice.

If I remember right, don't you have to modify the GM alternator? Maybe drill out the pivot boss? Anyway, I don't care for the one wire setup and those old GM units don't put out as good at idle. I'd rather have a big alternator that puts out 20%-30% of capacity than to have a smaller unit pushing 50%-60% capacity. Less strain and less heat equals longer life IMO. I wanted something popular because we do long hauls in this car like 1000+ miles in one trip and I know there are a million Mustangs on the road.

Nice setup MoparGuy, looks pro.

White70JavelinSST wrote: Nice setup MoparGuy, looks pro.   Wondering how the wiring is done and what regulator is used for that Motorcraft alternator.   AND,   Where did you find that tightly curved heater hose?? That appears to be the key to your install, the clean reroute of the hose.   Armand

Thanks Armand! The regulator is internal and here is a diagram for a Mustang that I used as a reference. I got a V belt pulley from a local rebuild shop for $5. That's the only mod needed to the alternator.



The heater hose I used is from a 2001 Chrysler Concord and yes it made the whole thing come together quite well. I was able to keep this same setup when I added A/C. All I did was switch the pulley to a double sheave and aligned my compressor with it so I have a double belt setup now.