Ultimate High Output Bosch Alternator fits 1985-1995
 

If you've been looking for a Christmas present for your 928, this will have your car thanking you for years to come!

After over a year in the making, it is finally here....The Ultimate 928 Alternator.

No more turning off your headlights, turning off the headlights, and reving the car up to close your sunroof!

I took a state of the art, new generation, high output Bosch Alternator and modified it for use in the 928 application.

One pound lighter than the stock alternator, this alternator fits perfectly.....with the original brackets and hardware. All you need to do is bolt it on and attach the field wire. No excuses, no nonsense....it fits in the original location....perfectly!

The result is 80 amps of output at idle and 150 amps of output by 2500 rpms.

Made specifically for high temperature engine compartments, the 928 application is not a challenge for this beast.

Attachment 1196175

Attachment 1196176

Features:

* Billet custom front housing for direct fit into the 928 application. Available in either "mat" finish (above) or in "billet" finish (below.)

* Brand new 80-150 Bosch alternator....not rebuilt. In testing in the 928 application, will maintain 13.8 volts with the headlights on and the A/C on high.

* Twin internal cooling fans

* Internal windings directly exposed to air flow through both front and rear vents in housing.

* "Free Wheel" pulley....a true one way clutch. Drastically reduces load on the alternator belt, whenever rpms are rapid reduced (when shifting or when shut off.)

Available in "billet finish".

Attachment 1196177

Special Introductory price, until January 1, 2017, of $795.00! After January 1, the regular price will be $995.

Special notes:

All alternator output is dependent on a good battery, good grounds, and adequate wire condition from the alternator to the battery.

Generally, the positive cable that runs from the battery to the starter motor is adequate for proper charging.

If you have my replacement "14 pin" wiring loom that goes from the front jump post to the starter, all my looms were constructed with a higher current capacity wire from the alternator to the starter connection. If you have a stock loom or anyone else's 14 pin replacement loom, please add in my supplementary alternator to starter cable.

If you have not replaced your engine ground strap or your battery ground strap (with something other than the factory battery ground strap) replace these items with a stock engine ground strap and our custom battery ground strap.

Confirm your battery is in good condition and not sulfated.

Wow that looks awesome! Does this unit do away with the cooling hose? If so what do you do with the temp sensor?

I've been just leaving the cooling hose tie wrapped in the general area in front of this alternator. Works great.

Ampacity of the supply isn't the problem with our cars. Resistance in the various supply paths of the car is the problem(as Greg rightly mentions). Of course, this requires a lot of wiring repair that most people are unwilling and untrained to perform. Some models have replacement harnesses avail, and for those that don't, it's a messy and complicated DIY job.

Awesome product, can you put one on my "to do list"?

Wow gorgeous !!! what an awesome upgrade ....

Awesome!!!

Ahh more car jewelry, just before Christmas,
Thanks for making this Greg !

The '87 and later cars (with electric fans) are very marginal, in terms of current output. Add in a high power stereo, a higher current draw blower motor for the HVAC system, or one of my upgraded A/C systems and the charging system will have a tough time maintaining 12.5 volts, especially at night.

(The main reason I made this alternator was because the output of the stock alternator with my upgraded A/C system was very marginal....and the added load from my A/C system upgrade was less than 15 amps.)

The reality is that if the cable from the battery to the starter is good enough to crank the car over, it is good enough for 150 amps to go back the other way.

The cable from the alternator to the starter was sized for the current alternator (except in the late model cars, when they increased the size of the wire.) Most likely, any car with an original loom needs one of my supplementary wires. If you have a "replacement loom", inquire with the builder about the current capacity of the wire used.

The stock ground cable from the engine to the chassis is plenty adequate....when in good condition. Any of these original ground wires needs to be replaced.

The stock battery ground cable is marginal....even when brand new. That crimped on brass end at the chassis side is......problematic.

Porsche quality there is no substitute ......

Looks like a great package!

Let me be the first to say..

I'll take it.

We'll install it when I bring Mr. Leaky down for warranty inspection.

The primary circuit from the alternator lug to the jump post, and the power post on the driver side aren't the problem. Neither is the primary from the batt + to the starter. The starter line only gets a hot shot for a few seconds while starting, although that generates plenty of heat which I've felt several times. No, the problem, as I said is the various current paths leading away from the primary circuits which add up to a lot of paths. You mentioned a couple big ones, and those are often the culprit. Anytime we see burnt CE fuse or relay connections, and semi-melted harness ends this is an indication of latent resistance chewing up current along it's path to the ultimate delivery point(fan, motor, lights, etc).

I do agree that at idle, with many circuits running like the AC on high, wipers, rad fans(part of HVAC), and some lights you are at the limit of the alternator supply. However, if all the wiring that served these various loads were cleaned up, and renewed as I've seen done before, a larger alternator isn't needed. Porsche specced the alt for a given load factor, and put in a modest reserve. The reserve they allocated is most often chewed up in the supply wiring to the ultimate end load. Sure, if a guy puts in a big stereo amp, that can affect the ampacity as well. But one would be better served to replace those old rad fan motors, clean every high amp circuit from end to end, and clean all the grounds, as well as replacing the batt ground which is another indicator of high resistance in the load paths.

But, it is a very nice looking alt, and having the free-wheel clutch is a bonus on decel.

Powder coated sparkly purple. Do you have that? Otherwise billet is fine with me. :)

More 928 jewelry. Almost too beautiful to hide. LOL. Awesome job Greg.

Looks fantastic Greg, job well done.

Greg,

That looks fantastic with the satin finish. Good job getting a clutched alternator out there. Its perfect for those running heavy load items with the multi-rib belts. Supercharged guys without a dedicated belt drive should take notice!

That was my thinking exactly.

I'm a firm believer that Porsche knew what they were doing, given the parameters of their goal.

And having worked on these cars since they were new, They did a really good job.

However, over the years, the parameters have changed.

The majority of the people that own these cars today, use them in a far different manner.

When these cars were new, most were daily drivers. That is no longer true.

The majority of the cars I see sit for weeks, slowly draining the battery. When they are used, they are generally working on a very low battery....sometimes jumped to even start the cars.....or charged only enough to start the car.

The alternator is then expected to both run the car and bring the battery up to full charge....very rarely occurring. It's not uncommon to see 12.5 volts (or lower on a hot summer day with the A/C running.) Headlights are dim, sunroofs barely function, windows work slow, and the injection system on the late cars is VERY dependent on good voltage.....sometimes resulting in misfires.

Rarely, the battery achieves full charge before the cars are parked...starting the cycle all over again.

These cars respond much better, when they can make over 13.5 volts while running and still have enough capacity to charge the battery.

Everything works better......all of the electric motors love the proper voltage and the correct operating speeds.

In reality, every single one of these cars will benefit from a high output alternator.

Without your help, this would have never happened!

Thank you, very much!

(Hans drew up the housing and made it possible to be machined on an CNC mill.....he's got a serious amount of talent.)

Thanks. That means so much, from you!

Do I need to supply a supplementary wire to people with your 14 pin loom, or have you done what I did and increase the size of the wire from the alternator to the starter, anticipating a change?

I increased it from the start with the option of going larger if requested :D

I have a little question. My Alt on my 81 has a V style pulley on the alternator. Would getting this alternator require getting a new crank pulley from a later car to get it to work?

Same goes for all the other pulley widths Porsche used over the years to drive the alternator.

Yes, new crank pulley. Though I think Jake Myers has retrofitted his '81 with the whole alternator/PS pump cassette from the S3+ cars, to run a polyrib- belt alternator. Perhaps he can chime in.

ok.

Will not work on early cars, without using different mounting pieces and drive.

I guess if I have to ask the $ I cannot afford this?

Bottom of post #1, $795 for the next month, $995 thereafter. I know enough about this project to know that between the parts cost, machine time, and the sweat equity, this is more or less a zero sum game for Greg and Hans.

I had the pleasure of testing one of these on my GTS. Here it is at warm idle, A/C on recirc, front fan on high, rear fan on three, highbeams and fogs on, Stereo on with the sharkwoofer thumping. 13.93V at the jump post:

https://webfiles.uci.edu/redwards/pu...%2012-2-16.jpg

Stock brackets, easy fitment. We had it installed in about 20 minutes.

https://webfiles.uci.edu/redwards/pu...%2012-2-16.jpg

Should I contact Mary? I feel you earned a small commission with the pics and stats. Thanks, Rob!

714-879-9072. Operator is standing by.

I'm always talking about the futility of making things for the tiny 928 market (along with my wife.)

For you guys sitting in front of your computer, here's the reality of doing stuff, like this:

I had to have 40 pieces made, before the CNC guy figured he could make a profit, cutting them out. I agreed and he bought enough material to make 40 pieces. Two of those pieces were "ruined" in set-up....so I ended up with 38 front housings.

At $795, I have to sell 25 completed alternators to break even....not including ANY development costs, engineering costs, drawing costs, labor to take the alternators apart and make the required modifications.

25 completed units to cover my actual cash outlay to buy the parts to do this!

My wife thinks I'm absolutely crazy, doing things like this.

I can't figure out why.

Done!

You know you're deep in the weeds of a project when you have to hike over to the machinist's shop to help him lift a freaking 6 foot long, 4x8 beam of aluminum onto the loading table for the CNC. Greg, what did that piece weigh? 300 pounds?

and 250 plus lbs of that turned into swarf ...

Well mine is lined up.
Greg is even conscientious enough to get on phone to ask about status of power wire wires/harnesses.
In my case I had removed the little original power lines along with the wire looms for the 14 pin. Replaced any bad wire and fabricated new power lines using 1/0 quality copper cable. All were thermally and environmentally protected with materials purchased from aviation supplier. Had to do surgery at the starter attachment for the cables terminal connectors were so large.
I never lost function or had issue with everything ON, but I was never comfortable with the drop off on the voltmeter. Always knew the battery was paying for it.
I am very curious to see the new alternator.
Thanks Greg for providing such a remedy.

12' long.....enough material to make 20 pieces from each bar. Each "chunk" was 7" x 7" x 4".

They said the chunks of aluminum were 400 lbs each.

The end product was 2 lbs.

That means they removed 18 pounds of material from each block......720 pounds of scrap. Very efficient....

In the end, he told me that the "next" batch would cost more....that he underbid the job.

Great news....

Greg, do you have any pics of the back of the unit ?

Here's a rear 3/4 view- the alternator has a molded backplate with two grooves to locate the business end of the FOE harness to the B+ post.

https://webfiles.uci.edu/redwards/pu...3-4%20view.jpg

Thanks Doc.

I sure did. and i will be bolting one on tomorrow at the shop. ill take some pictures for us early folks.

I did this upgrade on my '81S and you are correct in that the power steering pump & bracket must also be changed with the front pulley.
The main reason being, the order of the belts, from the balencer out changed when Porsch went polyrib.
Also, one extra mounting hole on the front of the block had to be drilled and tapped. This was achieved with a right angle drill head.

Almost the only solution, for the early cars.

Porsche didn't go to a 6 rib belt because they got bored.

Pretty unlikely a "V" belt will drive a 100 amp alternator....much less a 150 amp unit.

Greg, when will these units start shipping out ? Craig

Pretty amazing response to this product, Thanks to all that have ordered or are contemplating ordering!

As long as Bosch doesn't run out of new alternators for me to modify and I dont get more than 38 orders (the number of front housings i had produced), I can ship within a few days.

The first 10 orders will ship today/Monday/Tuesday, depending on Mary's ability to process the orders. I should have 10 more ready to ship by the middle of next week. Not all of those are currently spoken for.

Can I reserve one for my car?

Yes. Thank you for your support!

Will also reserve you the later drive pieces and mounting pieces for the later 6 rib belt.

To think a "V" belt or the early 3 rib belt will drive one of these monsters is ridiculous. Porsche figured out they couldn't do this, reliably, with just over 100 amps!

Just makin sure you saw this. ;)

Thanks Greg! Looking forward to my "GB928" in the future.
-Hoi

Yup, got it.

Just not counting it, because I don't have to build it and Mary doesn't have to ship it, right now.

Such great products coming out of GB's shop.

OK! for us OB/SOB folks. Now my car has the S3 PS/Alt bracket, and obviously the crank pullet to go along with it. The exchange from my GM unit to the Uber unit took all of about 20 min. and most of that was due to having to pull up the shark fan shroud to get the long bolt out (not needed with the new bolt provided).

photos are pretty self explanatory. MM pics are at idle, and at idle with every single thing i can turn on turned on.

On the drive home in LA traffic i used my Laptop (mega squirt system/Tuner Studio) to watch the voltage that the CAR sees. not just at the jump post. never dropped below 14v, even when heat soaked in traffic. lowest i ever saw was 13.7 when coasting to a stop, and it recovers to 14v in a heart beat.

i will report more on real world results as i DD this baby.

Interesting stuff, there.

Because my alternator is equipped with a one way clutch on the pulley, the alternator will freewheel when the engine slows down rapidly.

That is why you see a voltage drop, which instantly recovers.

As I recall, the GM conversion was supposed to be better than the stock alternator.

Any idea of what the output of the GM alternator would be, in the same drive?

Yeah, when letting off the throttle after accelerating past 4500 or so, there's a very tranisent dip on the voltmeter as the pulley freewheels. Like a manifold pressure gauge when the the blowoff valve operates.

Scratches head again. The alternator speed will never be less than the crank drive speed, always at or above idle speed while the engine is running. Meanwhile, Rob and Jake's tests show that the alternator will deliver enough current to maintain about 14 Volts even at idle speed. No reason to expect the voltage drop. In fact, you are selling the idea that there won't be one.

The one-way clutch seems like it won't do much if anything an auto gearbox car. Just the rotating mass of the crank plus the torque converter would seem to prevent rapid crank slowdown on throttle lift. Any real-world feedback on that yet?

Nope. When we work on Mr Leaky, we'll install it.

I disn't initially think much about this one way clutch until I saw it in action....this "piece" is very new, to me.

While I knew it would come into action when the crankshaft quickly quit spinning (engine shutdown), it also makes sense (to me), that it must also work when there is a rapid deceleration of the engine, like when shifting or slowing down.

While the alternator obviously is making its own resistance to turning because it is working to produce electricity, it also has an inertial factor involved.....that armature is spinning very fast.

If the engine slows quicker than the alternator, the one way clutch seems like it should come into play, until the rpm requirement equalizes....taking all of this load away from that belt, which would normally have to "absorb" this rpm change.

I'm thinking that the rapid transient drop in voltage output while slowing or shifting, with the rapid return to prior voltage output might be a sign of this activity.

My actual total knowkedge of what is happening would only occupy a couple of your brain cells....I'm just trying to be logical about what I am seeing.

I'd be happy to hear a professional power generation expert's "spin" on what is really happening.

Idle voltage looks good. What temp conditions apply. I find with a hot engine on a hot day, the voltage goes down.
Nice product. As usual from Greg.
Dave

Greg, during the same drive with the GM alternator, when hot id see about 12.8 at the ECU/CE panel, and at hot idle a tad less than that. now nice an cold/fresh in the AM i could see around 13.8 at idle but it did drop pretty harshly due to heat soak.

This week i will take my IR gun with me and take some immediate temp readings and MM reading when stopped after stop and go, and freeway driving. I can tell you that after the drive home yesterday and getting home, and getting the kiddo in the house the case temp (id say about 10 min) was 93F. but I'm surest cools off fast.

Superb Greg........looks and performance.........I'll take one please.

PM sent.

What Dr Bob says - there is no explanation for a voltage drop here... The one way clutch allows the alternator to spin faster than it would without the clutch - not slower.

It will always spin at least at the crank RPM * Crank:Alt pulley ratio and is allowed to spin faster than that on deceleration - so while 'freewheeling' it can generate better not worse.

There are other alternator pulleys available - the Litens OAD clutch pulley has not only a freewheel mode like this but also a soft drive decoupler to soften the impact of engine pulses on the belt and provide a smoother drive - avoiding common causes of belt slip and extend the belt life.

http://www.decouplerpulley.com/

Alan

Greg,
I'll take one as well.
vb

in rapid decelleration doesn't the charging system sense that as its fully charged and the engine is in a no-load condition the smart regulator disipates the alternator charge through the regulator hence the dip in voltage readings?

if these thoughts are totally off the wall then im blaming the frigid temps........-30c again today :(.......wheres the Scotch!!!

I can always take a data log and check the RPM-load-temp-voltage correlation.

The alternator itself doesn't have any speed-related dynamic voltage adjustments. The regulator just sees output voltage vs "setpoint" and adjusts the excitation current to the rotor accordingly. The setpoint changes based on temperature to protect the battery and the alternator stator windings, but since the load and temperature don't change instantly on decel, I don't have a good electrical explanation of why you'd see the momentary drop in system voltage.

It may be as simple as how fast the one-way clutch "recovers" after releasing on fast decel, a mechanical drive issue. In a long-ago past life as a packaging machine designer/engineer, accommodating these engage/release/engage parameters "just right" was always a challenge, especially in equipment drives that changed speeds a lot. The clutches have little rollers that act as wedges in one direction to engage, and there's a minimum rotation (in degrees) required to let the rollers shift, plus a time component from the mass of the rollers as relative directions changed, and the time it takes to re-accelerate the load once the rollers do move and try to lock up again.

perhaps not engine speed related but load related as in min. load on decel ?

Im assuming the readings have been taken after the regulation portion of the system and the workshop MM has a relatively slow ability to instantaneously read the output values.

I like the idea of the data logger for those who may have serious concern.........I dont as our wide open highways are ideal for go driving vs stop :)

I don't think anyone has any "serious concern"....just general interest in how the free wheel pulley works and what affect it has under quickly decreasing engine speeds.

When I started this project, some two years ago, I considered many different alternators for my starting point. While some may have fit easier, they didn't "make the cut" in terms of the performance and reliability I was looking for.

The alternator I picked to use comes from a later model 911 (and variants), which all have a hellish engine compartment temperature and high rpm potential (the 911 and 911 variant application has a slightly larger drive pulley size than our 928.)

Frankly, if the alternator can work in a 911 engine compartment (which has temperatures several hundreds of degrees higher than we will ever see in our location) and can survive the rpms of a 911 engine, my intended application was a "walk in the park" for this alternator.

As an added bonus, its made from all brand new components (not rebuilt), completely designed by Bosch (legendary reliability and performance, not "tweaked" by some alternator rebuilder with his own "backyard theory" on how to make more power), has twin internal cooling fans, exposed coils, has this great one way clutch (which significantly reduces belt heat and wear), and was close to what I needed to fit in the 928 location.

This seemed like the perfect starting point for what I was trying to make.....all I needed to do was make it fit.

Here it is....I think it is beautiful....and it works like a dream, in the 928 application.

it is of great interest Greg........hence my order, cheers :)

my posts are general cabin fever ramblings that, if nothing else, will help provide everyone who is paying attention technical answers from the masters who know.

That answered my question, the clutch is good for the belt, works for me.

Greg, I just did a bunch of load testing, very interesting. Sign me up for one please. (Sue would prefer the mat finish).

The bottom line is if we start the car and turn on the defroster and headlights, then we are discharging the battery; the stock alternator is done.

The way this pencils out for our GT is 42 amps just to run the car with the radiator fans going-- this includes a '044 fuel pump, in-tank pump and wbo2 maybe 35 amps for stock.

Now crank the blower up to max and the voltage drops from 13.9 to 13.4 (i.e. barely charging). If we turn the lights on then it goes off the cliff-- the voltage drops to 12.5 as the battery starts helping out. The alternator is maxed out at 55 amps, won't go any higher-- the battery just discharges faster.

That's at 675 rpm, S4 idle-speed (in neutral; in-gear is 625). Our GT normally idles at 800, in that case with blower and low beams the alternator is putting out 77 amps at 12.9 volts-- still half-over the cliff. If we crank it up to 2000 rpm then blower plus low beams is 93 amps, and the voltage is 13.5 volts. With high beams the alternator hits the wall at 105 amps and the voltage falls off the cliff again.

This is with no stereo running, no cosmic subwoofer, no rear A/C blower, nothing else. But we do have Roger's bigger blower motor, and H4 headlights.

The impressive thing with the stock Bosch alternator is that it will hit its specified output after a many years and many miles. The problem is that the specified output just isn't big enough.

Pictures or it didn't happen: Front to back is computer for Sharktuner (to diddle the idle speed), jump-post volts and the little multimeter for the clamp-meter on the alternator.

Attachment 1116032

Attachment 1116033

...AND...without engine bay temperatures to make it worse.

Great detailed data, Jim!

Exactly what i found out, with my custom A/C upgrade, with more details about what each individual piece adds to the current draw.

Any additional load in these cars (upgraded A/C system, better headlights, stereo upgrade) pushes the current load past what the stock alternator can put out.

The number of original alternators still in these cars amazes me. I have changed very few of these alternators for reasons other than bearing noise. I can't remember ever changing one of the stock (late model) alternators for electrical reasons.

This is one of the main reasons I stuck with Bosch for my high output alternator project....reliability was high on my list of requirements.

I do think the primary from the alternator to the jump post and the jump post to the CE panel are often problems in our cars - with age especially - and to some extent even from the very beginning (both are undersized IMO).

It is also important to understand that any resistance that builds up over time due to poor connections, oxidation/corrosion on the way to components - e.g. in fuse-holders, connectors or directly in the wiring causes overall LESS current to be consumed.

It's not that extra resistance consumes or wastes current along the way (which is rather how it sounds described here) - rather it's that it just never existed. Resistance in the circuit just makes the loads seem smaller, so less current will be consumed when they are operating. There is also a power loss across the resistance (voltage dropped * circuit current), but the extra resistance alone directly causes the current to be lower at any given voltage. The load itself will therefore see a compounded power reduction: The current at the load will be lower and the voltage at the load will be lower too - because some voltage is now dropped across the circuit resistance.

What this means overall is that extra resistance in the supply wiring makes the alternator's job rather easier not harder (it needs to supply less current*). Now this isn't a functional benefit because equipment will still be running problematically (e.g. slow motors /dim lights)

*However because of this the alternator may hold its voltage up a little better - compensating a little.

We usually measure voltage at the jump post, but this is not the true source - when running the source is normally the alternator - so measuring there directly would be best. If you do measure there and the voltage is drooping at idle with lots of equipment on - then the alternator is at fault. If you see a big difference in voltage between idle and 2K+ RPM then the alternator is also at fault (assuming the battery is ~OK).

Now since we are usually measuring at the jump post - what we actually measure is the voltage after a possibly significant voltage drop across the alternator to jump post wire, a common enough problem area. A good idea would be to have a separate unloaded sense wire in the loom from the alternator to the jump post area so you could easily measure the alternator voltage directly.

Measuring the voltage drop over this Alt to Jump Post primary wire is a worthwhile exercise - a voltage drop >>0.1V @ idle should trigger fixing this connection. Cleaning/improving everything else is of benefit mainly to each system itself. As Greg noted also check the engine ground strap condition - it is also part of this loop.

I do think this time of year is not the best to test alternators - the most challenging time is mid summer when fully heat soaked at night, idling with AC & cooling fans on full with all lights. This is the real challenge - and it is mostly driven by the aggressive temperature compensation in the regulator and the poor low RPM generation at idle for the stock alternators, (esp for low idle RPM cars).

I agree with Jim - the stock alternator is quite marginal at hot idle (and the hotter the worse it is - Phoenix is NOT good for this), any extra loads take you over the edge quickly..

To me an alternator that can reliably generate better at idle RPM and also one that de-rates less over temperature is a good thing for a 928 - in moderation. I do think the biggest problem here is the alternator and secondarily the primary wiring. Now the "in moderation" is important - because charging your battery at 14.5V continuously - even at high 30C temperatures runs a very serious risk of damaging it (or exploding it). You could boil and lose electrolyte and suffer serious outgassing if you run this way long enough. So ideally you'd have some direct battery temperature control over charging, but typical alternators don't do this at all - all they have is a setpoint voltage at the alternator and an (alternator) temperature derating curve.

Based on the hot idle results Greg shows this alternator seems to still perform just about right in this respect - good.

This is a great option here (though $$$) - especially for cars with extra loads to drive or that live in very hot places.

Alan

I realize that in a parallel circuit as each circuit increases in resistance the sum of the legs will increase. But I don't see the total resistance of the loads going down much. Lights are lights, and motors are motors. They aren't regulated circuits and they need what they need. (if that is rather how it sounds, I guess I didn't do a good job of description)

The key to my posts was that no matter how much current you're developing, my original theme was to correct the resistance loads that aren't contributing to car operation. Having said that, my subsequent post after Greg brought up the deal about the idle performance, I was convinced and said so.

Thanks for that explanation. We are very fortunate to have a resident electrical expert who is willing to share his vast knowledge!

I always assumed, now to find that my assumption was incorrect, that an increase in resistance (through oxidation or a poor contact) increased the current draw through an individual circuit.

Makes total sense when I stop and think it over ....if the current draw actually went up, the fuse would blow.

Thanks for the insight!

Again there simply are no "resistance loads" any added series resistance causes reductions in the existing loads - never additions. Series resistance is always additive - and you don't have any added parallel resistances in this case. Lights are lights, and motors are motors indeed - but what current & power they get is dependant directly on what voltage they see at their terminals - this will always be a lower voltage when there is series resistance in the circuit. This lower voltage will mean they will also get less current than they would get without the resistance present. The total power transferred to the load will be a lot lower too because it is then ~a square law to the voltage reduction.

Circuit current here is always dependant on voltage, there is power consumed in the resistance but there isn't any current addition due to the resistance. Net current & total overall power will always be less than a case without any added series resistance present. It's not always obvious or intuitive - but it is always this way.

Alan

Great to talk with Mary today......new power on its way :)

I fell asleep on the couch last night, with a 'working with your DVM and diagnosing voltage drops' video.

Was good to learn how to do it right.

Silly question...

Is a voltage drop always the same across a bad connection, regardless of the voltage being fed to it and load behind it?

I want to say "yes".

Hi Greg,
Does your alternator require a separate ground cable from the alternator to the body like other high output offerings?
Nice as always.
Roger

I thought that additional ground was just to allow a direct grounding port from the alternator to the chassis, not actually required since alternators ground themselves through the block via the installation brackets.

Yea, I was sorta chuckling about the idea of a separate ground strap. Very odd set up.

Truthfully, I don't see any need for that.....just seems like unnecessary stuff. Perhaps it is needed because of the funky adapter brackets that are required on that other offering, which look like they are powder coated black (which is not conductive.) I have no idea.

The bare aluminum body of my alternator bolts solidly to the huge aluminum bracket for the power steering with 10mm bolts, making contact with that bracket in three separate places. (Just like the stock alternator.) That bracket bolts directly to the engine block with two 8mm bolts and one 10mm bolt. Again, with three separate points of contact. (Completely stock.) No cheesy adapters required....this alternator bolts directly to all the original mounting pieces with all the original hardware.(*)

If anyone needs more grounding than that, they have worse problems than needing a high output alternator, right?

Also, there is no separate "lug" on the Bosch alternator for grounding....so they obviously feel it is not necessary, either.

(*) I do include a shorter bolt for the upper pivot. The rear threaded portion of my alternator has a more modern captive nut. This allows the use of a 110mm long bolt, instead of the stock 130mm bolt. While the stock 130 bolt works perfectly, getting a 20mm shorter bolt past the fan housing is a real blessing. (Anyone that has pulled that bolt out and has had to reinstall it knows what I'm talking about.)

Another side result of circuit resistance is the heat create by the power loss.

For example if a piece of wire with a resistance of 0.01 ohms will drop 0.25v at a 40A load current, then it gets 10watts of heat dissipated in it.

Greg,
Put me down for one and I guess I'll need a supplementary wire on my original harness that is on my 91 S4.
Thanks

Careful with what you discredit. The accessory ground wire on Carl's alternator is a Good Thing. Every load except the starter, temp sensors, injectors, plus a couple other small things, grounds through the chassis rather than the engine. Any resistance between alternator/engine block and the chassis risks havoc with injectors, temp sensors and the like. A direct ground from alternator to chassis removes alternator electrical noise from those systems.

Look at how later cars have a separate ground braid from coil brackets to the engine at the heads. One might presume that the heads are very securely grounded through the block. But -any- corrosion on the head bolts and mounting surfaces offers chance to leave some ignition voltage in the heads. Can you say "galvanic corrosion" three times fast?

So a direct ground from alternator to the chassis adds protection from injection and sensor errors, avoids possible galvanic corrosion issues across the mostly aluminum ground path to the other side of the block, and also electrical noise issues that might show up in audio components. What's not to like?

Further, the original ground point positioning under the coolant reservoir overflow is less than ideal. I get that the other side is clogged with steering gear and all on LHD cars. Still, from a functionality point of view, having individual connections from starter to frame, alternator to frame, and coils to heads makes much better electrical sense than what they came up with. It was good enough while the copper braid was new, and relatively easy to assemble on the car.

---

If you haven't done so already, REPLACE the copper ground braid between chassis and engine block under the right side of the engine (on LHD cars anyway). It will do charging and engine sensors nothing but good. This piece is one of only several very reasonably priced pieces left on the car. Grab an extra for later, when copper prices approach gold standards.

Bob:

If you read my original post, you will see that I put emphasis on making sure all the grounds are in perfect condition. I also offer a complete ground kit and an additional power wire between the alternator and the starter, if there is any doubt.

BTW....the starter does ground through the engine and then into the chassis. Goes through the stock ground strap.

Realistically, if the engine ground wire is good enough for the starter to turn the engine over (250 amps minimum load), an alternator that puts out 150 amps (maximum) isn't going to have any issue getting the power back to the battery....through the exact same ground strap.

That being said, when changing the alternator, it is a great time to review and refresh (if needed) any ground connections/cables. I've already emphasized this.

The large majority of my clients are trying to keep these cars as original as possible....or as close to original looking as possible. Hanging an alternator with cobbled up mounts which needs an extra ground cable run which is secured into the chassis by drilling a hole and adding a screw isn't going to fly, with almost all of these people.

Like I've also hinted at, these Bosch people have a pretty good handle on what is needed for electrical pieces.....and I'm using the same alternator to engine block attachments that they do, in the original application of this alternator. And....the engine grounding strap and chassis to battery ground are actually smaller, in the original application.

I didn't have to re-invent the wheel. My alternator mounts from the same locations, ends up with bigger ground straps, has the same size power wire (as in my looms), spins at a lower rpm, now operates in a lower heat environment, virtually jumps into the car with all the original hardware, weighs less, and looks so similar to the original that no concours judge is ever going to know it is there.

It just produces more amperage, which almost all 928s, with just the addition of a modern stereo with an amp and a subwoofer need.

In summary:

No "extra" ground wire hanging under the alternator, randomly drilled into the chassis and secured with a screw required in my application.

Just make sure what is there is good.

Thank you for your order. While I appreciate it, Mary really appreciates it....she had to write the check for this crazy project!

How are your engine and battery grounds? I'm asking every single person who is buying one of my alternators this question.

I made a complete "kit", with the original engine block to chassis ground strap, a significantly better battery ground strap, and the supplemental wire that goes from the alternator to the chassis for an additional $75, when purchased with the alternator upgrade.

Please call Mary at 714 879 9072, so she get this order going. Don't forget to tell her your tee shirt size, so we can send you a complementary shirt.

XXL

XL

Ill take that kit as well.

Any chance to visit and knock out some of our issues over holiday??

PM sent.

Upate from me. :-)

Day to day here in LA, in traffic and on the "parking lot conveyor belts" aka Freeways, i see a constant 14-14.2 while moving. Heat soaked (been kinda cool here), the lowest is 13.6-13.8. WAY better then the low 13's and mid 12's i was seeing with the Delco

What is the story on that Delco alternator? It appeared to have some sort of an adapter bracket to be able to mount it onto the stock 928 bracket.

Who came up with that idea/adapter?

Any idea on how many amps it made, before it got hot? (Old design Delco without exposed windings.....they get really hot.)

Greg, please put me down for one for Turq. Please include what else you think I need since it has your AC upgrade.

No - it varies hugely dependant on the resistance. In a highly resistive case you can drop essentially all the voltage across the extra series resistance so the load gets ~nothing or it could be a matter of microvolts dropped that you would never even notice. It is likely that most poor connections will simply get worse over time - oxidation or corrosion continues to worsen - heat causes faster degradation so resistance goes from low to high over time too. You don't need much degradation to start to notice it. Voltage drop is also usually approx proportional to the supply voltage - it varies if that voltage varies.

Alan

Thanks Alan..ive learned some fun new stuff this week.

Ill be hunting down and exploring voltage drop areas around my car this weekend I think.

Now..can you also see a drop on the ground side too..not just in the '+' current path of a circuit?

Like..from the head of a bolt at a ground point to the '-' post of the battery?

Yes. Before or after the main load, resistive elements are all part of the complete circuit, between '+' and '-'. Example in a simple 12V circuit .... 20 ohm load, with 5 ohm resistance before, and 5 ohm after ... '+' to load would measure 2V, across load 8V, and from load to '-' 2V. Every single resistive element (e.g: poor connection or low rated cable) in a circuit will have a measurable voltage drop across it, no matter where it is in the circuit.

Exactly what Dave said!

And note that all conductors (esp small wires) have intrinsic resistance per length, so even before any contact degradation etc there are always some series resistances to the loads - they are just small.

Alan

I will have to dig in to some emails, but someone on here with machining skills made that adapter. i want to say it was an 108 amp Delco off of an mid 80's V6 camaro. It worked, but heat was not its friend.

I used a marine bilge blower behind the left front grille to blow cool air through a 3" duct to cool my aftermarket alternator. It makes a huge difference on a hot day.
Dave

Not too difficult to understand why that alternator was affected by heat.

That Delco alternator, like our original Bosch alternstor, has one fan, which draws air through the back, flowing through the interior, and out the front. The "current generation" coils are externally surrounded by the aluminum housing.

When there is a rear plastic cover, like on the stock alternator, the cooling air comes from a remote, cooler, location....which helps some. With that Delco unit, the cooling air comes from behind the alternator, which is pretty hot, in our application.

It had to get very hot, which explains why you lost so much efficiency as the engine got hot.


Never alternator designs (like I used for my upgraded alternator) have two fans, with the "current generation coils" exposed through vent holes in the aluminum, to cool them down much more efficiently.

Pretty cool!

Great idea!

In stock and ready to ship 8>)

I tried a couple of blowers before I found a quiet one. This is what I used:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I'm sure Roger's is great too.
Dave

Just an added note on the Bosch alternators...I had the original alternator in my early '86...still chugging...I had converted it to electric cooling and had same issue everyone else has...low rpm charging...got a souped up version from some folks that added extra windings or something and brought it up to 150 amp..otherwise I'd be signing up for one of yours Greg...I have always admired the quality you put into your executions...

Unbelievable how tough these alternators are...30 years for mine??? No american car would ever have an alternator last that long...

Yes, to be able to get 5 years out of an American alternator is considered to be "good". For a "tweaked" American alternator, the expected life span goes down, considerably. This is why I went with Bosch.

Obviously, I can't tell anyone that my new alternator is going to last 30 years, like the original, there just isn't enough track record on these alternators to be able to do that.....but it is Bosch....and they are word renowned for their electrical pieces.

Another one of the really great things about what I'm doing (that I haven't mentioned) is that if my alternator goes bad (comes with a 2 year warranty), all people need to do is order the rebuilt exchange alternator from Bosch (~$350), swap out my custom housing onto the rebuilt unit, and then install the housing from the rebuilt unit onto the "core". Instant rebuilt alternator with a "core" to turn back in! (This takes about 1/2 hour.)

New alternator on the B and the O, old on the S-C-H.

You have waaay toooo much time on your hands 8>)

LMAO!

FIFY

Greg Brown.
Can't say enough about the guy.
Spoke to Mary about shipping date, and asked if Greg was at hand for a quick tech question.
He wasn't at hand but came in anyway and took my call. Helped with my two technical questions and also said he was sending out new belts with the units for he didn't want any issues. I was going to change out the belt and his new alternator after the thaw, but he was a step ahead.
Can't say enough about the guy.

Pm sent, had enough of the charging issues, this looks like a great deal. I am not sure how to get hold of Mary as this is an overseas order.
Merry Xmas.

Just want to make sure you got my order.

Best way is to email Mary.

MaryBBRD@att.net.

I just emailed Mary

Yes, we did. Thank you!

I'm assembling.

Mary is processing and shipping.

Received mine today! Thank you. I forgot to open and look.

You what ?? You forgot?? To open it?? No pics?? You are undeserving, send it to me! :D

When Mary ships, the toughest part of the installation is the actual opening of the package.

While I'm not positive, I'm pretty sure she starts with a box, but there's so much tape involved (several different types), you can't really tell....and it probably isn't really necessary.

I tease her that if the world as we know it came to an end and there were only cockroaches left, they would be living in her boxes.

That's if they could get inside.:D

Funny, it is the exact same size as one of my 100 count Super Cedar boxes so I thought what fool returned these. Later I noticed it was from Precision 8:30 pm. If you want it come and get it. I owe you.
Merry Christmas
Thomas

Not to worry, your alternator is safe! I think Greg has me covered :D
Merry Christmas :cheers:

Attachment 1195532

Six more ready to go, today.

Mary will get some of them out today....she is waiting on a couple of people to send Emails back.



Thanks to all that ordered this high output alternator! I never dreamed the desire for this high quality, high output alternator would be so great. I'm already past the break even point for the machining of the aluminum covers!

There's still time to get the introductory special price. We will be in the shop through Wednesday, next week. If you miss us, you can send me an Email or a PM before the 1st and the introductory price will still apply.

Thanks again, for all your support!

Got to thank Greg for doing this for two reason, great product and I've sold a few harnesses due to it. :)

Thanks. To get your approval means a lot! Hopefully Roger will stocK them and you can install one (or many). The function and fit lives up to the pictures!

And I'm glad you are selling looms....seems like every car needs one, unless they have less than just a few miles.

I've been disecting all the ones I change in my own shop....the condition inside the covered section (by the airpump) is appalling!

the tracker says the little brown truck is on its way.

after the triple taped package is open I'll post pics of the new 'power' unit :)

The Browns (Greg, Mary and the truck) outdid themselves! The UPS tracker said next Tuesday but it got here today. Whee! But I don't know where you guys get "20 minutes", I spent that getting the box open and admiring it!

Here it is, about to get hooked up and lifted into position. Everything fit perfectly. (That's a GB harness, fit last year when the engine was redone).

Attachment 1121295

Gotta love Bosch. The spec is 80A at idle, 150 max. I warmed up the engine, alternator was putting out 14.3 volts at around 30 amps. For a load test I set the idle to 675 rpm, lights on, blower on high, and the alternator put out 86 amps at 12.97 volts-- no drain from the battery. That's at a stock 675 rpm idle. The comparable number for the stock alternator was 55 amps-- enough to run the car and either the heater blower or lights: Choose one.

The scale on the current meter (big display) is 1mV per amp, so 86.1 amps from the alternator. A separate current meter on the battery was showing a small charge (1-2 amps).

Attachment 1121287

After running at idle another 30 min or so it was doing 80.1 amps at 12.88. If I dropped some load then the voltage bounced up to 13.5 or so, and adding more load the current stayed at 80 amps but the voltage dropped-- and the battery stepped in to help. That is all as expected. It's not mid-summer in Phoenix but things were pretty toasty-- car was indoors in our heated shop (exhaust vented outside). No airflow, and rad fans were cycling.

Attachment 1121282

Then I set the idle back up to 800 (the usual idle for our GT, and also what most alternators are spec'ed at for idle ratings). A load of 104 amps was the best I could come up with quickly, the alternator just laughed and put out 13.54 volts-- i.e. enough left to add charge the battery, if it needed any (it didn't).

Attachment 1121283

I'll get some miles on this (and let the brushes get properly seated), re-tension the belt and then do some full-load testing, I've got a load box that can add another 50 amps.

But first impressions are that the Bosch alternator behaved exactly as expected, and is a big step up from stock-- especially for the later cars with bigger loads, electric rad fans, etc. And Greg hit it out of the park with the billet housing and adapting it for the 928.
And Mary, what can I say? Well done !! :cheers:

Thank you Jim for the very detailed writeup on the working of this alternator. Not that anyone was doubting GB's work, but we appreciate it nonetheless.

Thank for having developed this for the 928 community, Greg!

PM sent to you for ordering of 1 mat one (just before the New Year starts here in Finland, only minutes away now).

Jim -- Excellent results and excellent (as always...) verification.

Greg -- win-win for all.


Thanks to both for making a great package!

I don't get PMs on my phone, so I won't see this or any other order by PM until Tuesday, bit rest assurred I'll take care of all.

Thanks for your order!

Just caught up with this thread after getting home from vacation.. email incoming, I need to order some other bits too, will ask in the email about them.

Couldn't resist putting an order in for this yesterday. Greg has done all of us a great service by making new/better technology available for 928's. This will be especially helpful here during the summer months.

No worries.

I only get very intermittent Emails where I'm currently at, so I can not respond. (Also not getting PM's.)

I'll be back in the office on Tuesday....and then I need to go through all my communications, plus get the shop back moving, after this break.

Because of this, I will happily continue the sale price a few days.

Just a passing thought:

Because Porsche needed more alternator output for the later cars that didn't turn very many rpms (non 5 speed cars), they made the drive pulley larger (which requires a longer belt) on the late S4 and GTS vehicles equipped with an automatic transmission.

Of course, the larger pulley used more horsepower to spin the alternator faster...

The early cars all used drive pulley 928 102 139 11, which is 5.160".

Late S4 ('90 and '91) automatics and GTS automatics all used 928 102 139 12, which is 5.480".

If you are using my new high output alternators on one of these late automatics, it's so efficient at lower rpms that you don't need to spin it faster....so keep your eyes open for the smaller diameter pulley and swap it, next belt change.

"Free horsepower"!

Of course, the inverse is also true. If you have an early car and you don't buy my high output alternator, keep your eyes open and find the larger diameter pulley (especially if you have an 1985-1989 automatic).

I can envision some pulley trading coming on....

its alive!!! :)

My garage isnt heated so shall wait for warmer temps to install; what a beauty.......thanks Greg, Mary and team.

I should have ordered a second :)

Conveniently, I'm honoring the special price until Friday.....

Jeez, another variable :D ... So our '90GT should have the smaller pulley, correct? How are you measuring? Outer rim, or top of the grooves, or bottom? Ours measures approx 5.388 OD at the outer rim...

Yes, you should have the smaller version. Only the automatics got the bigger version....supposedly.

Pretty easy to tell by the different belts. We sent you a short belt. If you had the bigger drive pulley, you would have never gotten the belt on.

Porsche did some sneaky things....both with this pulley and the A/C drive pulley.

I'm measuring to the top of the grooves, BTW. Your outer rim measurement is correct for the smaller pulley.

Yep, belt went on, easily. Thanks! :cheers:

OK, so that means that earlier cars and GTs used the smaller pullies, correct?

Yes. Only one (small) pulley until 1990.

Fantastic news

Wow! My dash gauge is now at 13.8. It has always been near 12.6 in the past. Great product GB.:rockon:

I haven't heard back yet - does that just mean you're still catching up with vacation email backlog and shop work?

I'm in no rush, just want to make sure my email didn't slip through the cracks :)

I sent it to the one in your sig on the first post Greg - was that the right address?

gregbbrd@aol.com

Cheers!

Mary is working on shipping. I'm pretty sure the quantity of orders has her overwhelmed....it takes a long time to make each box is bomb proof, bullet proof, and certified to survive a small nuclear explosion.

And there is always the chance she is waiting on another truckload of packaging tape.....

I'll check and see how she is doing and where you are, on the list.

1990 Service info tech blurb about 90+ alternator pulleys and belts, for posterity:

https://webfiles.uci.edu/redwards/pu...%201-11-17.jpg

I'm not fussed how soon it ships - just wanted to make sure I was on the list - email isn't a reliable communications method - between spam filtering, server outages etc.

Thanks for making it!

Update:

I finished another batch of a dozen (12) alternators today, which should fill all the outstanding orders.

Mary will be shipping on Monday and Tuesday. If you haven't heard from her by Wednesday (for the final details), there's a very good chance you've been forgotten and you should contact her at 714 879 9072 or MaryBBRD@att.net.

I'd like to sincerely thank everyone who ordered or expressed interest in this product! It has been an incredible success....far beyond what I imagined. Thank you all!

From here on out, Roger at 928 R US will have inventory on these Bosch High Output Alternators.

Greg,
I installed my new alternator while replacing upper and lower control arms on my 88. I test drove for 50 miles last night and all was well. This morning when I started the car my volt gauge sat at 10 volts for about 20 seconds before bouncing up towards 14 volts. Does this alternator have a stall type feature? The idiot light on volt gauge never triggered and it works properly.
It was awesome with all the accessories on while idling waiting for my citation for 5 miles over the speed limit. I should have gotten at least negligent at 40 over but the trooper liked the car and performance apparently.

Mine came in last week and appears to be a work of art.

Isn't the power steering mounting casting of the 32V cars backward-compatible with the 16V cars?

If that is true, and I remember reading somewhere that it is, then the newer alternator should also be swappable.

Somebody ought to try to confirm that.

The idiot light should light.

Disconnect the single small wire to the alternator and touch it to ground with the key on. The idiot light should light.

That's what I have on my car. Pretty sure I have more time/mileage on this alternator than anyone, works like a dream.

The idiot light comes on with ignition on. My concern was more with the 20 or so second delay before needle bounces up off 10 to near 14.

Is this RPM dependent or you start it and it takes that long to register? How is the voltage at the jump post during that wait time?

Sean,

Once the car is running (right at start up) the needle stays on 10 volts for 20 seconds
then goes up close to 14 volts. This has only happened once. I also notice the needle has more movement than with the stock alternator.

Beautiful work! And a slipper clutch! We have had these for a good 5-9 yrs now on our sport bikes so we can bang downshifts from a high gear to a low(er) gear while full-on the brakes to make the corner and not have the rear wheel slow down and or stop spinning -- when this happens the accident is almost certain and a good 60% of the accident has already happened before we riders even realize the rear wheel has locked up. That's a very fair and decent, even too cheap a price for this Stromerzeuger!

Installed...started car...checked voltmeter...


https://cimg7.ibsrv.net/gimg/rennlis...f80d745361.jpg

Greg's High Output Alternator
 

As others have said, this one of the best things you can do for your 928!

It's an amazing experience after 19 years of 928 ownership, being able to sit and drive in traffic with the A/C on, fans running, turn signal on, and radio playing, while having the volt meter remain rock steady.

I had a good stock freshly rebuilt alternator and it worked "fine," but this is a big difference. IMO, it's another improvement that makes the driving experience, and the car, feel exactly as they were meant to be.

Many thanks to Greg for taking the time and effort to address the need for improvement and develop a solid solution, and for making it readily available to the 928 community.

Installed it yesterday.
14.1 V on cold start up.
13.2 V with headlights, fog lights (both incandescents), and fans running low after pulling in garage after 1/2 hour on highway.

Actually, that is low, compared to what we' ve been seeing.

Check battery age/condition.

Did you get new ground cables and positive wire to starter?

6000 miles, car could not be happier. never need to use a trickle charger.... ever again.. LOL

Good point.
I'm a little overdue for the two ground cables.
The cable to starter is likely needed, but further down the list.
Battery has little mileage on it. Spent most of its recent life with my unattached during the winter sleep.

So, I have one of these alternators in hand and the motor needs to be put back together. We also have a new front main harness from Greg that will 100% be part of the refresh.

I have two questions:

1.) 928s leak a lot of oil around the area of the alternator. However, this alternator does not have shielding like the stock alternator. It is true that the stock alternator will probably ingest quite a bit of oil despite the shielding that the fresh air hose is hooked up to. My car shouldn't leak any oil once re-assembled. BUT, is this a potential problem, if the motor is not completely sealed compared to the stock alternator?

2.) Getting back to heat, is there not some way to hook up the fresh air hose? I understand that the newer 911s supposedly have a hotter engine compartments. But, it also seems not correct to just leave it hanging there.

I am just trying to put all these observations into perspective. Can anyone comment?

This alt was originally from a newer 911 and those run much hotter than most 928s ever will so a cool air supply is not necessary in our application.

I also wouldn't worry about oil getting ingested. The shielding behind the alt is only there to direct the cool air supply from the back to the front of the alt and give optimal cooling to the diodes.

I'd fix the oil leaks regardless. No alternator does well when sprayed with oil. Even the stock unit is sort of open in front around the pulley and fan. the new one from Greg has an axial outflow fan in the middle, so will be drawing in air from the front and rear. If there's oil loose in that area, it will get in and coat the windings.

In my limited experience, oil on the alternator comes from leaking cam cover gaskets, sometimes camshaft seals, but most often from power steering hose leaks at least on cars I've had my fingers in. Be sure to replace any tired PS and maybe the oil cooler hoses on your car.

Most cars have open-frame alternators. Somehow they survive. I know from personal experience that they don't do well with engine cleaning chems, so better to keep it clean than to let it get oily and try to wash it.

My bad. I meant to write "911s supposedly have hotter engine compartments." I edited above. I still wonder what one can do with the fresh air hose.

Bob, I am not the kind of guy to leave things leaking in an engine compartment. (Not that you could know that.) I will have ALL new hoses on this car including a complete set of Greg's fuel lines.

Nonetheless, given the oily messes I see in engine bays, we have to stay the stock 928 alternator does an excellent (or at least way above average?) job dealing with massive oil slicks...

The restriction on cleaning with cleaning chems might be a good thought with this alternator given the open design. In Northern EU countries, it is standard procedure to wash down engine compartments prior to inspections. I am going to talk to some people about how this handled with 928s.

I've had no reports of any issues from oil, on cars equipped with my alternator. Perhaps everyone who is installing one of these has engines that don't leak, but I'm seriously doubting this is the case. Certainly, the voltage regulator is encapsulated and doesn't care about oil. The "windings" are wire covered with that clear, super tough, winding insulation. I guess if there was a "flood" of oil that got to the alternator, the brushes could get oil between them and the armature....but I'd think centrifugal force would make pretty quick work of any oil there.

I've got to think that alternators are designed with a certain "tolerance" of oil, since they live in an engine compartment.

As far as the cooling duct is concerned, I simply leave it close to the front of the alternator, if it is in good condition. I've also thrown a couple of them away, if they are badly damaged. From my testing, I've found that this newer designed alternator (with the windings exposed and fans on both ends) do not suffer from the same heat soaking that the original alternators did. The cooling duct is essentially a "vermiform appendix" when using my alternator (as far as I'm concerned) and I place it near the front of the alternator simply to pull air through the hose for better function of the temperature sender for the HVAC system.

:corn:

My negative experience with cleaning alternators is rooted in using solvent-based chems and then water to clean them on the car. the bearings are good but still manage to suck that stuff in and start the failure routine. No doubt it's easy to clean an oil-fouled alternator. I've done it often enough. I've learned by experience not to try to do it on the car. Learn from my experience. It's cheaper and easier than learning stuff like this on your own.

Are these still available…..

Yes.

We try to keep a couple units assembled and ready to ship, a the old pricing.

Bosch has been increasing their prices on....well, everything.
Including the alternator that we build our "928 version" out of.
Mary has been able to "hold the line" on our price, for now (by reducing our margin.)
However, she told me, after the ones we have are gone, the price will have to increase.

I've been considering one of yours Greg to solve my non-charging while idling issue on my TwinScrew 86.5 928, with all three Fans (after market - two pull and one push) running.
This is especially bad in stop and go traffic on a hot day when the pusher fan is needed and or AC on, as the engine will start to miss as the voltage drops to 11.5 :(

I recently had two Stock Alternators rebuilt and they tested at 140 amp output at speed, unfortunately I didn't get the idle amp output, I see yours is at 80 amps, correct?
Do you know what the stock Alt puts out at Idle please?

Thank you,

Dave K

Sorry, but I do not.
And you are 100% correct. The ignition system and injection system on these cars is very "power dependent" and requires more than 11.5 volts to be happy.

All I knew was that the stock alternator, even freshly rebuilt from Bosch, was barely adequate for a stock S4/GTS with the A/C running, the stock fans running, the stereo on, and the headlights on.
And people with big output stereo equipment were in trouble.

When I added on my upgraded A/C system, which had an additional fan and a higher amperage main interior fan, the stock alternator could not keep up, at idle.

Put one of Greg's alternators on mine (which replaced a one year-old rebuilt stock alternator) and it made a big difference, especially in the Florida heat. IMO, it's one of the best things you can do for a 928.

I'm so glad I bought one back when they first went on sale. My current alternator seems to be losing the juice when it gets warm. Can't wait to get Greg's unit installed.

I can tell you when I put Greg's alternator on the battery got much needed relief and starting the car from cold the starter spins significantly faster. Un-rebuilt windows run up and down better. Stupid voltmeter will sometimes read below 12 V but thats because it needs a pod refresh. I did the Bosch rebuilt alternator thing with extra windings but same thing for me, it doesn't charge at idle so you really aren't any better there.

Put Greg's alternator on; its a great piece of kit for our cars...looks cool too! Also, get the supplementary wire; it goes from the other alternator terminal to the starter...nice little boost and easy to thread through things...I just followed the original wire pathway and zip tied it to the orig wire to hold it in place.

I'm certainly not trying to "pimp" these alternators...my stuff sells quite nicely, all by itself.

But I just wanted to mention:
I've had a fairly big run on these units, in the last couple of weeks....and I went back and counted how many actual billet housings I have left to actually build this fantastic product.

I have the capability to build 6 more of these alternators, currently.
And since my CNC machinist did not "survive" Covid, I will be forced to have another machinist program and machine my housings and then make another "run" of these.
That's a major re-investment and will only occur after I have enough "back orders" to rationalize having that many $$$$ invested.

That could take a few years....
Long story short, if you've been on the fence on ordering one of these, you might want to hop off the fence and get it done.

Delivered…installed…14volts at idle. :rockon:

glad it included a belt, mine was def on the way out.

https://cimg5.ibsrv.net/gimg/rennlis...6b754f6d3e.jpg

https://cimg1.ibsrv.net/gimg/rennlis...5e8e277441.jpg

If you're on the list to get one of my alternators, made from what I have left of my custom front housings, I have assembled them and Mary has them, ready to ship.
I've got a few more housings left (and new alternators at the "old price"), to build three more, if you are not on this list...
I'm going to have to find a new machinist to make more housings...so alternators after these will take awhile.
And the price will never be as low as it is, right now, ever again....
https://cimg4.ibsrv.net/gimg/rennlis...641d2b3be7.jpg
Custom high output alternators ready to ship.

Greg sent you a PM.

Greg, sent you a PM and left a vm.

PM sent

Greg, sent you a PM