When do you need to upgrade the alternator???

[chrismorse]

My dad's 74 owner's manual indicates 66 Amps, or optional 88 amp unit.
The chassis electrics are basically stock, except for 55/60 headlights, normal radio, Odessy smuggler's box battery and twin EDIS ignition, (2x20 amps) and EFI, (13 additional amps).
AC was deleted in favor of a front cooler, but may go electric AC if i win the lottery.
I've built and wired a few houses, but sizing the electrical panel and sizing the alternator are clearly different.

Appreciate any advice,
chris

[wazzz]

If you go electric AC you'll probably go the Classic Retrofit way. They sell an upgraded alternator suited to requirements of their electric AC.

[pavegeno]

I upgraded to Classic Retrofit. I have a voltmeter in my car and would watch the volts drop whenever the a/c compressor cycled on (Griffith's 4 condenser system w/electric fans on three of the condensers). This combined with headlights, upgraded stereo amplifier, etc drove me to the high capacity alternator. Very happy with it.

Here is the link: https://www.classicretrofit.com/en-us/collections/upgraded-alternators/products/copy-of-porsche-911-high-output-175a-alternator

[Flat6pac]

If you get a fan housing with the thinner back spacer, not Carrera, but SC 80/83 you can use the larger alternator with on board VR.
Bruce

[chrismorse]

Thanks Guys,
Classic Retrofit makes solid stuff - I've got their fuse panels installed.
Bruce, You've been around the block a few times, Without electric AC, how big an alternator do you think will work, given my set up??
Thanks,
chris

[47silver]

add up the ants of everything that uses electricity and multiply by 3.
100 watt high beans = ~9 amps each or 18 amps
cdi or msd ~ 5 amps
~running lights
radio
etc.
alternators are designed to duty cycling, on and off, and from what I can determine my 75 was designed for 33% on and 66% off.
of course when you start the car the alternator will run 100% of the time for a bit to get the battery recharged but once that is done the alternator will run about 33% of the time..
I assume it needs time to cool off.
175 amps would be great but a 70 amp should get you about 33% unless you have a super large amp and maybe electronic suspension with hydraulic pumps.

[Flat6pac]

Without going to Carrera, I prefer the 80/83 unit with onboard VR and it’ll install on all housings from 75 on with the 19mm back space. The heavier threads on the shaft and the 8mm Allen center is a plus too.
Bruce