Alternators and their Interchangability?

[euro911sc]

So I spent the weekend at the track, Homestead, recharging my battery between sessions. Car ran great on track! New suspension is awesome!

On the way home I made it to within a mile of my friends house before the car completely died. That was about an hour and 45 minutes drive time on a fully charged Optima battery. Not too bad! It lasted 10 minutes with the headlights on though after I re-charged it at his house... It was dark then I did make it home with the assistance of my dad so no worries.

Anyway... I'll need to replace or fix it. Pelican has a few to do this. I am not interested in spending $730+ for a 'High Output' alternator... that's just WAY too much money, IMHO. That's 3-4 track days! For an alternator! Seriously?!?

I remember reading an article about using a later model Carrera alternator as it has a higher amp rating. 90 vs. 75 for my SC I believe. Is this just a drop in replacement or not? Do you need a Carrera fan setup to do it?

Comments and advice please

If you have a spare SC or Carrera alternator collecting dust I may also entertain PMs on those Though I am trying to find a local re-build shop that can handle it. We'll see...

-Michael

[Flat6pac]

82 SC should have a Paris-Rhone or a Verlo with the on board voltage regulator on the back.
The regs go bad, you might just get that and be on the move again
Bruce

[euro911sc]

Yeah I was hoping that was the case, but Pelican doesnt sell the parts to do that. That's why I was looking at a local repair solution. Though the 2 shops I called 1st were not helpfull, the 3rd one said he'd look at it and see what the could do.

Looking at VR replacements it looks fairly straight forward to do once you get the part off the engine. I'll have to pull it and see what make it is. When I rebuilt the engine it looked fairly new, though I have owned the car for over 15 years so it is at least that old.

-Michael

[c2kid]

this might help with what fits what. cheers, geoff

[group911@aol.co]

What are you running that a good 75 amp alternator won't keep up with? I just tested one
today rated at 75 amp and it would do 110.
Take it and have it tested. They can do it in the car I think.

[cmonref]

I remember reading an article about using a later model Carrera alternator as it has a higher amp rating. 90 vs. 75 for my SC I believe. Is this just a drop in replacement or not? Do you need a Carrera fan setup to do it?

Michael,

The SC and Carrera alternators are different lengths -- 14 mm according to Geoff's chart. It requires a different fan mount. A Carrera alternator will not simplly drop into your SC.

The fan IS the same, however.

Brian

[Grady Clay]

Michael,

I have raced SCCA GT2 where my 914-6 was not required to have an alternator.
I simply use the stripped alternator body, the shaft and two bearings.
This nicely supports the fan and fits the fan housing.
This dramatically reduces the rotational inertia of the engine and the loads on the fan belt.

The battery is a standard 911 88 A-hr battery, in a battery box at the front of the passenger foot-well.
I have a small (600 W) Honda generator with 12 V output to recharge between track sessions.

The current draw is for two Bosch fuel pumps (one to re-supply the surge-cell and one for the circulating fuel system for the 46IDA).
Additionally are the CDI and instruments. I rarely use the brake lights

This is sufficient battery capacity to even spin-out and crank-crank-crank-crank-…. clearing flooded carbs with a 1.5 hp starter and very high CR (not me driving) during a race.

For your application driving to and from events, you might consider an ‘external’ alternator from some other car.
You could use some old A/C brackets and mount the alternator as the A/C is normally positioned.
You could remove most components for an event.
Check the rules.

Just thinking outside the box.

Best,
Grady

[Joe Bob]

Retail remans suck.....my choice is to always find a local rebuilder.

[euro911sc]

Thanks guys! Especially for the info on what fits what. I use the car on the street at least once a week for my weekly maintenance drive to work so I will end up putting a working alternator in the car.

@Grady: Great idea... but you could give me 20 more horses and I'd still be slow

@Bob: I'm not running anything but the ignition on track or any other time. I do have a clock... *shrug* I have no idea why it failed... but I suspect it has something to do with being 30 years old. I doubt I'll ever really know

I pulled it out tonight and I'll drop it off at the local shop tomorrow at lunch. They will look at it and tell me if they can re-build it. The fun part will be if they call me and tell me its operating perfectly fine... hehehee