GregBBRD

Our high output alternators start life as a brand new Bosch alternator for a 996/997.
We disassemble them and change the front cover for a billet cover, which make the alternator a direct fit, onto a 928.
They are not cheap! (Think about the cost of the "starting point" and the cost of making a billet front housing....and you should understand.)

Being a modern alternator and not someone's "hot rodded" version of an "old school" alternator, they have "exposed coils" with dual fans. They also have a one way pulley, to greatly improve belt wear.
And if you think about where a 996 or 997 alternator "lives" in the engine compartment, they are made for high heat environments.

We're on the 3rd run of billet housings (and almost out of those), so we've sold about 60 of these units.
Zero returns. Zero failures, Zero issues, what so ever. Zero complaints.

Another one of our long list of custom 928 pieces that is the very best that money can buy.
....Frequently "duplicated" pieces, but never near the same quality.

Rob Edwards

GB alternators: Recommended by one out of one Rob Edwardses who install alternators.

Instigator56

@Greg Brown, @Mrmerlin, and @Rob Edwards, thanks for supplying this information! Dare I ask, how much is "not cheap"? Also what is the power rating? I didn't see any mention of it under the "Products" section of your website, so its good to know that this alternative exists.

Zirconocene

Those 996/997 alternators are the business. I have one out from the Cayman right now and have been spending idle time thinking about how to make it work on a 928 because they output A LOT of power in a very small package and, in the Cayman and Boxster especially, must not get very much airflow at all. Given how the engine covers and insulation work on those cars it's a bit of a wonder that those parts last any kind of time at all. It makes a ton of sense to use them as a starting point and I don't think you'll go wrong, especially from Greg.

That said, I also explored and went the route suggested by Rob Edwards and installed a Ford alternator on my 968. It's not exactly plug and play, given the differences in some of the wiring, but neither is it crazy and those alternators fit the OEM space pretty well. Best of all, it's hard to beat the price, though I'm sure you're not getting Porsche quality from a low cost Ford aftermarket supplier.

Good luck

GregBBRD

$895, until the "current batch" of alternators and billet housing are used up (very low inventory.)
At the rate that German parts prices and billet chunks of aluminum are going up, I would not be shocked, if the "next batch" was 25% more than that.

At 14 volts, these units are rated at 80 amps at idle speeds and 150amps by 3,000 rpms.

Our "Website" is intentionally vague. Allows people to find our phone number.
We do not have very many of our products (especially all the very latest ones) on the Website.

We understand that when people attempt to copy our products, it is the highest complement that anyone can make about our products,
but it does get old.

Almost everything we have is "bought" through word of mouth.
Many products are only available when a vehicle is in our shop. (Kinda like "Singer Headlights"....you get a set when you buy a Singer Vehicle.)
We're becoming more and more like a "928 Skunk Werks".

Instigator56

So, your price isn't bad when compared to the Porsche OEM alternator!

1) How long would it take to receive one if I ordered soon?
2) Would I need to install it with the alternator cooling shroud and hose?
3) How does the performance compare with the Porsche-rebuilt OEM alternator?
4) How would I place the order?

Darklands

Well done!

This unit is so sexy, you should store your car upside down!


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GregBBRD

1. If I have one on the shelf, however long it takes to ship. If I have to assemble one, a couple of days plus however long shipping takes.
2. Shroud no. We simply run the cooling hose to the front/side of our alternator. The original style hose is stiff enough to stay in place. If you are running a silicone based hose with wire inside, simple to tie wrap it to the alternator. We can provide either hose, if your has fallen apart.
3. No comparision. Old design alternator with coils hidden inside housing, with one fan. Heat soaking occurs on all alternators as they get hot (reducing charging) but the stock unit heat soaks badly and has a tough time running headlights, cooling fans, A/C system, plus the engine. Common for charging voltage to drop below 12 volts. It is very common to find a stock alternator that is not capable of generating 100 amps.

Worth noting: We developed this alternator because we have an A/C upgrade, which converts a 928 into a vehicle with "modern" cold/high volume A/C system. Our upgrade adds another fan and changes the HVAC fan motor to a higher volume fan, which requires more amps.
This upgrade increased the need for a higher output alternator.
Once we started producing these, people with late model 928s, which have marginal stock charging systems, discovered these worked fantastic and we have sold many, for this application.
4. Call Mary at 714 879 9072. She will accomidate:you. Our alternator comes with a new, factory belt, a new upper mounting bolt, and a connector to hook up the "blue" field wire.

A few potential "hidden costs", depending upon your car: (if you have been running a "high output alternator, you might/should have the following.)
1. If you have not replaced your stock battery ground cable with the latest version, from Porsche, you need to do this. Mary can provide this...already modified to fit your battery, perfectly. (Porsche frequently "looses sight" of specifications, when reproducing items.)
2. If you have an older, corroded, stock ground cable, from the chassis to the engine, you can replace this with a new stock ground cable or our updated, thicker ground cable. Mary can provide either.
3. If you have an original 14 pin loom or one of the lower grade reproductions, the main power wire back to the starter is too small, for the increased amperage. We can provide a supplemental cable that runs along the side of the stock loom, from the alternator to the starter. (Our replacement 14 pin looms have increased positive power cable size, making this "extra cable" unnecessary, if you have purchased our 14 pin.looms, in the past.)

Obviously, when making "changes/upgrades" to an existing car, there are frequently associated pieces that are not "up to the task". Fortunately, we have the "vision/expertise/experience" to be able to address these issues, right up front, instead of the client getting something that does not perform to their expectations and them needing to "add" something to make it work.

Do it right once, with the best parts available, and forget it.



.

Alan

Its good that you think you've located the problem - but I don't really understand the failure mode. If the alternator isn't generating it isn't loading the engine at all - so why does it cause the voltage to drop at idle?
Yes voltage would be low but it would always be low. Possibilities are that the fans kick in at idle dropping the battery voltage or that the alternator does still generate but only at higher RPM, or that it intermittently drops in & out causing dynamically changing loading. If it weren't generating at all you'd have seen major battery problems - as the battery alone cannot sustain summer running (w/fans on) for more than a few hours before losing all charge. Have you been charging the battery to keep it going? I think a good alternator/motor shop (they are getting to be a rare breed) could possibly set you up with a replacement regulator for the alternator you have. Although Mechman probably don't have the custom made parts that make this work on a 928 I'd be very surprised if it didn't anyway use a standard regulator of theirs. So instead of asking about Carl's stuff - send them a picture of the regulator and ask if they have replacements (13.8V or 14V set point is what you want - no more). These were expensive (as you know) - so I'd try to keep it going.

Alan

Instigator56

@Alan, I’m not going to say that I understand this either; a lot of things in “928-land” have been an education. I’m not completely convinced that there might not be something else to discover; however, I believe that fixing the alternator challenge will be a step (big or small?) to working out all the problems associated with this scenario—e.g., maybe identifying a bad relay or two.

I believe that the battery has survived this long due to my religious use of a battery maintainer. After I had the entire audio system replaced in CY 2019 (in Peabody MA by Autobahn Performance), from head unit to antenna, my MD mechanic (Eurosport Auto Care) discovered that the amps were causing a current drain that had killed my first new Interstate battery. After some “R&R”, I had a battery maintainer (and second new Interstate battery) installed, instead of a battery cutoff switch. Nearly two years later, we found out that current leak was caused by several loose power leads going to the amps. Fortunately, the power wires were so stiff that they didn’t pop out of the connectors and cause a 1000-amp meltdown! Needless to say, that problem was fixed right after it was discovered.

Up to now, when I’ve started the car (after disconnecting from the maintainer) the car was at 13-13.5 V. However, the car would always drop voltage with each restart during a drive and eventually hover around the 12 V voltmeter mark. Since the 928 Motorsports (aka Mechman) alternator replaced the 30 YO OEM alternator, which would struggle to stay at 11 V under the same driving scenario, I believed that 12 V was the best that I could hope for. However, after reading a couple of Rennlist posts recently (What is the correct charging voltage? and Alternator light stays on + 3.5A current leakage + dashboard lights act up) I now know better.

I don’t plan to junk the Mechman alternator when I replace it. However, I do have to find a good alternator shop to work on it—and you’re right, they are getting harder to find (especially in the Washington DC area).

mdkelly1

Greg Brown's alternator is one of the best things you can do for your 928! Replaced a freshly rebuilt stock alternator with Greg's unit and never looked back. It's a must if you actually want to have A/C and other electronics on a very hot day in heavy traffic. You'll see the difference right away.

GregBBRD

Never trust what the dash voltmeter, in a 928 says, until readings are confirmed with a quality voltmeter, at the jump post or battery.
As these cars aged, this gauge generally became notoriously inaccurate and variable.

That said, there is a consistent phenomena which we do not understand, but are happy to see.
Invariably, when we remove and "rebuild" (clean and deoxidize/replace corroded fuses and relays) a fuse/relay board, voltmeter will again be truthful and steady.
When we first started seeing this and getting reports back from clients, we dismissed this as just a coincidence.
Hundreds of relay board rebuilds later, we now expect this...but do not understand why.
Alan?

84dizzy

Greg I'd like to buy one of these from you! Let me know how to proceed if you can spare one. Thank you

84dizzy

Bit of selective reading and missed this post of yours. I'll contact Mary beginning of next week. Thanks Greg

GregBBRD

Perhaps worth noting, for those running higher output alternators:
As I mentioned above, the stock late model 14pin/alternator/starter loom has 4 square millimeter wire from the alternator to the starter and the jump post.
When brand new, this wire had "marginal" ability to carry 100amps of 14 volts of DC power.
30 years later, it is certainly not better at this task!