prescott

Planning my Fall TB job and thinking about replacing my current 30 year old stock alternator with the GB unit. The stock one supplies enough current, except when full load is demanded with AC on, headlights on, windshield wipers on and stereo on (. Under these conditions, the lights noticeably dim when the wipers cycle. My CE panel was replaced several years ago, all new fuses and relays, all grounds are clean. Can anybody chime in on how the GB unit compares to just leaving the old "borderline acceptable" 30 year old unit in place?
TIA-Brian
1988 S4, manual

Speedtoys

Mountain of difference.

Best single thing I ever bought.

khalloudy

mdkelly1

Head-to-head there is no comparison between the Greg Brown alternator and the stock 928 alternator. At least that has been my experience. Greg's unit is much superior to the stock unit. I removed a recently rebuilt stock alternator that worked reasonably well and installed Greg's unit mostly for peace of mind, and was genuinely surprised by how much difference it made, especially at idle with the A/C on in traffic. IMO it's one of the best things you can do for your 928.

SeanR

Putting a proper harness and alternator is going to be one the best things you can put on your car going forward. One of Greg harnesses, or mine, along with this alternator is going to be fantastic.

hacker-pschorr

It's absolutely the best non original alternator available for the 928.

It's the only non-original alternator I'd install in my 928's.

Really? Mountain of difference?
All 5 of my 928's start up instantly (battery is charged) all my electronics work, headlights are seeing full voltage etc.... so what mountain of difference will I see if I swap them all over to this unit?

It's a fine alternator, more modern design than an original, I'm sure they will be more durable and long lasting, and great for cars with aftermarket electronics putting a higher demand on the system the stock alternator was never designed for. But let's not go overboard here.

Anyone having electrical issues should read Sean's post and start with wiring. The best alternator on the planet will be at the mercy of aging and damaged wires.

the flyin' scotsman

I fiitted a GB alternator and Seans harness on the S4 and had such great results Im also fitting the same to Sharky.

Great products that bring peace of mind to our aging cars..

Ghosteh

I've heard that phrase before & it always ends up costing me money!
I'm such a sucker for doing the "best thing I can do" for my baby! They can't ALL be the best thing.

Speedtoys

If you need an alternator, its the best thing.

If you need an oil pump, not so much.

dr bob

GB's alternator needs the bigger primary wiring to deliver full benefits. Whether you buy the alternator with the wiring harness or not, the wiring is needed. You might be able to fudge and just replace the primary wires between starter, alternator and jump post, bypassing inthe primary in the existing harness. But the work is the same or more than doing the whole thing right with a new harness.

----

Several years ago now a 'lister PM'd some questions about how to make sure he was getting the full benefit of his much bigger capacity alternator. Conductors that will handle the full alternator capacity on a continuous basis are BIG. Fortunately the duty on the alternator tends to be less than continuous at least in normal street driving service with a good battery and good wiring in the car. The alternator works hard shortly after startup, carrying the normal loads for the car, plus quickly restoring the battery charge spent spinning the starter motor. As battery terminal voltage comes back up, the demand for charge current drops to almost nothing. Sitting in traffic with AC and all the fans running on a hot day seems to be when folks get fixated on the voltmeter in the dash. How low it dips is a function of load, battery capacity, alternator capacity at engine idle and off-idle RPMs. Worse on automatic cars where extended chugging along can be at less than 1500 RPMs or so. Still, it's expected that the battery will carry the load difference that the alternator doesn't deliver. Eventually you get going again, and the now heat-soaked alternator takes a bit longer to restore charge to the heat-soaked battery. While the GB alternator has an impressive max current capacity, for most of us the benefit comes from it's ability to maintain an adequate fraction of that capacity at lower engine RPMs. We don't have anywhere close to the full rated current as continuously available load, at least until we have multiple batteries and that 5KW competition sound system in the spare wheel well.

dr bob

Everything I do to and for the car seems to cost something. Whether it's the "best thing" or not is always debatable. Mid June, the "best thing" was adjusting tire pressures down from hibernation numbers. The new "best thing" after that was taken care of was a quick-detail session after the duster. After that, the "best thing" was fresh fuel. Today the "best thing" will include another cleaning, this time with interior window surfaces included. The list of "best things" is endless. Money and time are somewhat interchangeable. Regardless, mine always gets the next "best thing".

crushingday

My neighbor got one of these alternators and has lost 20 lbs, looks happier than ever and has a peaceful glow about him. His lawn is also now the best on the block. Cholesterol went down too! Also, his wife no longer uses the words "That's fine" and "whatever" in a passive aggressive fashion. ...So, he's got that goin' for 'em.

ROG100

Proud to sell the GB alternator. Sean's harness along with a new battery ground strap and engine ground strap.

GregBBRD

My upgraded A/C system adds another fan and upgrades another fan, which draws 5 more amps.

That was too much for the stock alternator to deal with, so I came up with this unit, primarily for that application.

Naturally, I also started selling/installing them to people that had regular stock 928's.

Truthfully, the difference is incredible....the entire car works better when the electrical system goes from 11.8 to 13.2 volts (under heat soaked high load conditions.)
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​​​​​ The headlights are brighter, the windows work better, the seats move faster, the dash lights are brighter, some people claim their engine runs better because the increased voltage at the ignition coils, makes a hotter spark!
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Everything electrical works better!

No doubt about it, I make a lot of pieces that improve these cars, but this alternator is the best single thing you can do for your 928, that I sell.
(Although my crankcase baffle and valve cover oil deflectors are a close second.....And the upgraded A/C system turns a car that always had marginal A/C into a car with "modern A/C."....that you can drive with a suit and tie.)
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The Forgotten On

Oh do tell more about the valve cover oil deflectors. I would love to add them to all 4 ports on my 89's valve cover when I do a top end refresh. Your crank case baffle has been great in my 81 too!

Back on topic. The increased capacity this alt offers at idle is fantastic.

It allows the car to have a more stable voltage being sent to the electronics so it should definitely run better, especially since that is what computers like to have supplied to them.

Back in the original thread for it, the original alt, before it got the GB treatment, was meant for an engine bay that is much hotter than our own so it is really happy to supply higher amps in our cars.