Second question mid build, as I mentioned on the other thread I’ve got a 2.4 L 911 engine going into my 1974 914. The 1974 9/11 would’ve originally had an external voltage regulator, I’m not familiar enough with my 911 set up to know if it also had an external regulator or if it was internal to the alternator..

Anyone able to drop some knowledge on that?

Thanks!

It could of been upgraded over time to an internal regulator. Get some pictures of the back of the alternator. It might have a built in regulator. My first conversion was a 74 2.7 911S US motor. It had an internal regulator. I dumped the engine compartment relay board and never looked back. It's also easy to make an engine harness for carburetor cars. You can also buy the 14 pin Male connector I used to mate to the 914 female is part number 911.612.113.05

Super helpful – thank you Steve. Will pull it out and see what I’m working with.

Just like Steve. I dumped the relay board, internal alternator on a 2.2S six. Purchased a engine wiring harness with the correct connector to match the 914's harness from Perry Kiehl on this site.....works great. Best, Mark

Yup.. Ditch the relay board, get an internal reg alt. simple to wire too. Make yourself a new engine wire harness with the 911 male 14 pin connector and you are good to go. I did that on my brothers 3.0 6 conv. What you see where the relay board use to be is a hot start relay setup.

The '73 2.4 E engine I'm planning to use in our 914 presently has an external regulator. Started researching options for an alternator with an internal regulator and so far haven't found the definitive resource that explains all the 911 alternator ins and outs. Looks like there's the wosp high output alternators, but they're pushing 1k. At some point the diameter of the shaft changed, so I don't think it's just as easy as getting a later model one with integral regulator and slapping it in unless you have an appropriate fan that'll fit. May even need the housing, but not sure. The rear air channel piece also looks like changed, and haven't found out if it can be easily modified or if a new one would be needed. This is all from memory when I was researching a few weeks ago.

Dan

The fan housings changed a few times. So, yes you need the proper housing to fit the internal reg alt. that will fit your engine. As for the air channel piece that can be modified. I did just that to make it fit on my brothers engine. I had to cut the lower portion to fit over the regulator. You could buy a new piece but I had a good one on hand that just needed the mod. After the mod it fit well. Mid 75 or 76 the housings changed with the internal reg alt. Then when the 3.0 came about it slightly changed again. I have all the info someplace and will post it here once I find it.

Attached a link from classic retrofit which has a good video/info.

https://www.youtube.com/watch?v=P9dy5wSbeHk

https://www.classicretrofit.com/products/co...175a-alternator

Great info Luke. Love the table, it's very helpful. The classic retrofit alt looks like the wosp. Lots of info around, especially on pelican and rennsport. With the price of housings and fans, I'm likely gonna stick with what I have, at least in the beginning.

One question.... are you sure the internal reg alternator began use ~76 or was it just the housing that would work with them started being used in 76? A couple of posts on various forums implied the internal was first used around 81 or 82.

You'd think that converting older 911 engines to internal reg alts would be a common thing, but my searches for "Porsche 911 alternator convert from external to internal regulator" just don't turn up anything that's been enlightening. That's when I decided to just drop it and move on to the next problem.

Dan

I think you can get a direct replacement new Valeo alternator that’s internally regulated.

Perry, thank you. Quick searches surely do look like they have a direct replacement with internal reg and not terribly expensive. Reviews on a few sites tend to indicate they're longevity is better than a rebuilt Bosch or a Paris/Rhone. It's good to know they're an option that looks economical.

Dan

If you do go the external voltage regulator route, make sure the regulator matches the alternator. Bosch to Bosch, Valeo to Valeo, xyz to xyz. If you mix brands, some times you won't get enough voltage at the battery to charge it. I ran into that problem with my 914-6 conversion project. I was about 1V shy at the battery to properly charge it.

This would be another reason to go with the alternator with internal regulator so you wouldn't have this problem.

I used this Valeo on my build. 76 3.0 fan housing with a new fan. Amazing how easy the wiring was.