macreel

Malcolm... I can't think why not. As long as the regulator
is compatible with the existing wire. The more (elec.) doodads
and widgets you add to the car require more watts; i.e. an
alternator with more (current) output.

Me ? I'm stock. Better stereo is wasted on my ears... jet
engines took them decades ago so OEM works just fine.

the flyin' scotsman

Racing motorcycles, Led Zeppelin etc got mine............it was a good time though.

I would mount the newer alt. and be done with it; MHO.

bronto

No, we only went about 25 miles out of Ojai before turning around and coming back. The newly birthed Elise Club of Santa Barbara already has pictures of the run on their forum. You can see my 928 in some of the backgrounds.

bronto

I lost you; which unit/years are you referring to as "newer". New than mine includes the Paris/Rhone one that's apparently trash, so which ones exactly are the best?

Is anyone seeing any evidence that I actually *need* to replace mine now?

the flyin' scotsman

Well almost every unit is newer than yours but what I was reffering to is the latest generation alt that was fitted to the s4, GT and GTS models.

If you read the Paris/Rhone topic you'll see it was only used for a couple of years.

No implication that you do need one................its your car do want you want.

SharkSkin

S4+ Alternators will not fit an early car without replacing the mounting bracket. There may be issues with mounting the early PS pump to the later bracket, I don't know.

Loren, the P-R(actually, they were bought out by Valeo) alternator that I pictured works fine for my relatively simple '78. I get 45-50A at idle, and 95A at 1200RPM & up. As I mentioned before, rotor speed on the alt is an issue -- this alternator was specifically designed to charge at a rotor speed of ~1600RPM, most alternators won't charge worth a damn at less than ~2000 RPM. I have been running the pictured alternator for about 10 months now with no issues. Of course, I have the shroud attached and the duct properly routed, or I might not be saying that.

I do plan to graft in a different alternator at some point, but I need to replace the crank pulley to make it happen. The Valeo alt is perfectly fine until then, and none of the high-current add-ons that I want are especially high priority. For the curious, there's more info here.

Also, the voltmeter in the dash, at least in my case, was so accurate that I think it's accuracy is limited more by the size of the markings/needle width/parallax error than anything else. With all connections between the meter, the battery & ground cleaned up, the dash gauge reads within 0.15 volts of the actual voltage at the battery terminals. More info on that here.

Lorenfb

"Also, the voltmeter in the dash, at least in my case"

You're the exception, as all the 928s I've in last 15+ years ALWAYS have an inaccurate voltmeter.
If you clean & solder ALL wiring connections, the gauge might possibly read correctly. Remember,
the gauge wiring doesn't go directly, i.e. a separate wire, to the alt output. It basically measures
the #15 voltage.

"and 95A at 1200RPM "

And that's the basic problem with this alt, i.e. it uses the same diode assembly as the 911SC
P-R which is rated at 75 amps. Thus, avoid load currents greater than 70 amps or the diodes
will over heat and cause their solder to melt. The diodes then fall off the diode plates.

Again, it's a totally junk alternator design! That's probably why Porsche only used
it for two years from the factory.

SharkSkin

Loren, we've had this discussion before. The voltmeter, once removed from the cluster and tested in isolation, was dead-nuts accurate. A few people have reported the same finding to me. I didn't have to solder any connections to get it to read within 0.15 volt, I simply cleaned all connections and applied contact enhancer. The few who have cleaned ALL relevant contacts that I know of have achieved a similar result, and IMHO this is adequate for the purpose despite small differences that may creep in due to various loads being present in the system. Don't blame the gauge, it's a high quality unit and I have yet to hear of a gauge that was tested in isolation and was not accurate -- though I'm sure they are out there.

I still think that the alt is adequate for my purposes, to keep me going on a basically stock electrical system with no large loads added until I have time to go after a more powerful alternative. I have heard reports of people going for many years on these units with no issues, so long as the shroud & duct are intact. If I ever did drain my battery completely I wouldn't use the alternator to charge it -- this is a bad idea regardless of the alternator used.

If you know of a different unit that will bolt up without having to replace all the mounting brackets, I'm all ears, but frankly I don't find it especially helpful to be hearing "that thing is junk" without hearing of alternatives that will work at the slow rotor speed encountered in the 928.

the flyin' scotsman

Dave, this must be the same test applied to the torque wrench of 'My Cousin Vinney' fame

I too found the comments re. the alternator not helpful for there was no solution offered but I have to assume, given a more modern alt of 928 application would physically fit, there's a solution near at hand.

Anyway, temp just got high enough to melt the frost and its Canadian thanksgiving; I'm going for a ride.

SharkSkin

Malcom, it's not quite the same test. I didn't just rip the calibration certificate for my multimeter out of some random magazine.

I really did research this in-depth, and it is true that a later 928 alternator could be made to fit. However, as I said above, it requires replacement of the whole mounting bracket on that side of the motor. I didn't pursue that far enough to find out whether the 78 PS pump would mount correctly to the later bracket... that is left as "an exercise for the reader".

the flyin' scotsman

..........by the gorgeous Melisa T

BTW, I read your write up on the pod removal and refurb; well done. I'm adding that to my winter projects.

Dennis Wilson

Dave,

Which connections did you clean to get so close? Last time I looked there were 7 connectors between the battery and gauge. Think I have hit all of them except at the starter and mine still reads .5 volts low. Guess it's time to hit the starter.

Dennis

SharkSkin

Dennis, having completely refreshed all connections in the fuse panel, all grounds except the one behind the quarter panel, and all connections in and around the pod, and IMHO all of those steps may have contributed something.

It was still reading >1volt low when I dug into the pod(most recent electrical refurb project), found that the gauge itself was fine, and cleaned up all connections in the pod as well as all connections to the switches in the pod... so that narrows it down to the pod/cluster in my case. If I had gone about things in a different order, like first the pod refurb then the CE panel, I might have noticed the improvement when I went through the CE panel.

Worse, I might have refurbed the pod, and adjusted the voltmeter to read correct, then refurbed the CE panel only to find my voltmeter reading too high at that point.

Lorenfb

"The voltmeter, once removed from the cluster and tested in isolation, was dead-nuts accurate."

Right, that's NOT the issue, i.e. it's how it functions connected in the car. I don't think the
implication was ever that the gauge ITSELF was marginal.

"Last time I looked there were 7 connectors between the battery and gauge."

Right!!!!!!!! And that's problem. Even after all the cleaning, there's still fluctuations of the
needle as various loads change. The real only proper way is to solder connections when
possible, and that may not solve the problem because of the push-on connectors.

Dennis Wilson

Dave,

Went through the pod a few weeks ago. It helped the gas gauge more than anything else. Guess I tackle the starter and under dash grounds next weekend.

Dennis