Technical Alternators......how big is yours

Getting ready to buy a new alternator for my 32 project. Curious as to what most people find satisfactory and when a certain size wasn't sufficient. I plan to mount it low so its not over the valve cover area, so size may affect my choice. I know I don't need an extremely large amp output, but want a decent output hopefully in a compact and reliable size.

 

I’ll let you know if my 50 amp works lol

 

Mine is 45A. Just needs to power lights, turnsignals, horn and coil. 90% of the time its just powering the coil.

 

80 amp nippondenso from a Toyota.

 

What ^^^^ he said-- Paulz

 

Here is a great resource. Poke around there is a section that has all the details and dimensions https://www.tuffstuffperformance.com/

 

My 56 Ford with the AC I added on high fan, head lights on, and stepping on the brakes (brake lights are a bigger draw than you think) total on draw is 33 amps. The powermaster Alternator I bought is a 100amp which many be their smallest for the street. I have their mini 60 Amp on my race car.
Electric radiator fans and electric fuel pumps really add a lot.

 

This might help. Or not.
Calculate the Amperage You Need (qualitypowerauto.com)

 

63 amp for 73 and up GM’s.

 

What motor, what brand of Alt do you want and do you want an external regulator?.

I use GM 10si in stock form, which means 50-63 amps, which is plenty. I also used a GM 10dn external reg at 30-35amp which works fine.

I've used these guys for starters before since they're kinda local to me (local when I go to the apple orchards). If nothing else they have some useful info.
https://www.qualitypowerauto.com/catalog.php

 

I have a 100 AMP alternator on the Ranch Wagon and the Deuce. HRP

 

It will be a 500 Cadillac. Don't want external regulator. It will have A/C and electric fans. Ignition will be electronic with multiple coils. No radio or big speakers......a small basic set up if anything, but probably none. Electronic guages , and electric fuel pump. Looking for a GM probably but a small Toyota will get a looksee. Open to any suggestions..........

 

"It isn't the size that's important, it's how you use it."

 

The alternator in my roadster is a Ford Motorsports item, purchased many years ago through the local dealer, thinking it is around 60 amps, not positive.
It's not the smallest and my frame is pinched 3/4"/side so had to get creative.

 

after you get your demand calculated, you can find one that may fit here. https://www.tuffstuffperformance.com/rt-5793-alternator-dimensions.html

 

I got caught in a set of cir***stances (weather, time of day and traffic) at Back to the 50's one year. With a 65 amp alternator, running wipers, defroster, cooling fan and headlights, it couldn't keep up and the signal lights wouldn't flash to allow others to see what lane changes I needed to make. High traffic made things a little uncomfortable. Switched to 100 amp, externally regulated Motorcraft alternator with good results. Big car, low mounted alternator no one can hardly see. It's all good.

 

Most ratings for alternators are at speed and not idling. A 100 amp alt only produces a fraction of that at the light. My Olds at the light with headlights on, brake lights lit, heater on, 8 track on, will barely flash the turn signals. And don't even think about rolling down the windows till yer moving again.

 

55, but only because it's so hard to find a 37 these days.

 

The link I posted above gives max amps and idle amps of the alts they sell. It also has mini alts for domestic (hot rod) applications.

Check this out......
https://www.qualitypowerauto.com/catalog.php?item=551

Mini alts:
https://www.qualitypowerauto.com/category_144/Mini-and-Universal-Mount.htm

 

Add up all your electrical demands and add 10% if you're really worried about it. Powermaster offers a GM CS-121-style alternator rated for 60 amps at idle and 100 amps at top end that fits in a 5x5-inch space. That would probably be more than enough for your application. People think things like electric fans draw an ungodly amount of amps but the most power hungry fan draws less than 60 amps in-rush and less than 30 amps during operation. I would bet that most charging problems people have are related to too small a charge wire and lack of alternator ground wire, equally sized. An alternator capable of making a true 100 amps at cruise with a 4ga charge and ground wire should be more than adequate for most of our old-timey hot rods.

 

You might want to check the mount for your alternator on the 500. They came with a 10SI or the big case 80 amp depending on the application.
If you aren't running a bunch of power eating accessories 63 amps from a 10 SI is fine. There are also 12 SI with the same physical size that kick out 80 or more amps. I think I still have one of those off an 85 Cad deville with a sideways motor in it that I pulled off and stuck in the stash. Either of those is pretty reasonable at O'Reillys with a life time warranty. That also comes under the keep it simple with an easy to find anywhere alternator. My theory is that common bolt on parts that might **** out on the road should be simple and easy to find. That being alternators, starters and filters a**** other things. Even if you ou have a polished or chrome case if the alternator it started out at is easy to find, you can stick one from a parts house on, stick the shiny one in the box in the trunk and deal with it later.

 

Nothing is for free , larger amp more power to create the amp during load . Enough power robbing for you to notice NO I don’t think so . My go to for many years is a GM 12SI . You can fix it on the road side , same as point ign , simple is my game plan .

 

I have a 100A from tuffstuff on the coupe, works great and looks like a GM 12SI. I upgraded to this several years ago due to the demands of electric fan. fuel pump, MSD. They are made here in USA. Ohio I believe,

 

Unless you have an electric fan, or electric fuel pump a 36a. is enough. But the cost isn't any different for a 63 a. so that's what I run on all of mine.

 

Man, I read that the generator in my car is supposed to put out 25 amps to be considered running properly.

 

Good Food for thought here......Thanks Guys.

Good picture and thanks for posting.......thats probably exactly what I will be dealing with.

 

Good question. My Spal electric fan draws lot of amps on my 47 Chevy. I originally had a 63 amp alternator, and that was not cutting it. I installed a 140 amp unit from Jegs, and that solved my problems.

 

I picked up an alternator from Mechman in Tennessee. It’s a standard 12si style, came with a card that said it made 180 amps.

 

Whatever a 76 vega has. One on the 350 in my 53 Bel Air I just went to O'Reilly and ordered a reman for a 76 vega lol. More than keeps up

 

I’ve got power windows, AC, and electric wipers. I’m running a standard GM replacement with a polished cash, either 80 or 100 amps, I don’t remember right now. I had to drill one mounting hole out to fit the larger Ford mounting bolt. I keep an old 36 amp in the trunk in case the new one were to quit, I could change it out in 10 minutes.