SharkSkin

Thanks guys. I think I'm going to go with the 130D, since it's a more robust unit. A bit overkill maybe, but that's just the way I do things. The thermo switch doesn't scare me -- as long as I'm generating enough power to keep my mondo fan running, I doubt that I'll ever get to the 280° needed to trigger the cutoff.

I have the Painless connector en route. All I have to do now is double-check the pulley offset and verify the rear housing "clock position" that I want -- need to check clearance. I don't want the connector on the top, I only need to see if there is clearance to orient it to the side... otherwise it will have to go on the bottom. Also they will be checking to see if they have the split bushings available to convert the 10mm mounting holes to 8mm -- if not I'll have to figure out where to source those, or make them out of copper pipe. Once I have all the details of exactly what I want, they will build an alternator to meet my need, and they can provide the 165A capacity within the stock housing.

I'm really looking forward to the day when I can get stuck in traffic on a rainy night and not have to keep a nervous eye on the voltmeter while I'm running the defroster(incl. AC), lights, wiper, aux fan, brake lights, etc. While I realize that the Bosch unit I have is probably marginal and could possibly be refreshed to "good enough" condition, I'd rather have the surplus capacity. I don't think this conversion is any more sacreligious than replacing my Porsche aux fan with a Spal unit -- less so, if you consider that Porsche didn't make the original alternator.

P.S. -- toofast, how exactly are you measuring amps output? Current clamp or inline ammeter?

Chuck Schreiber

Dave,

I know you're planning a write up on your web page, right brutha?

toofast928

SharkSkin,
"P.S. -- toofast, how exactly are you measuring amps output? Current clamp or inline ammeter?"

Inductive clamp of a VAT-40.

SharkSkin

Yeah, I have some other site updates to catch up on too. It's been a busy year, and even on the projects I had time for I took fewer pics. Big props have to go to toofast928 though, for starting this thread and getting my gears grinding.

SharkSkin

Cool, I'll be using the same method, similar tool.

928FIXER

It was the small case cs series.I was installing one on a customers 88 camaro 2.8 v6 and it look like it be a great replacement for the 928.Pulled the 928 onto the other rack in the shop and held it up to look at the mount ear location and could not beleave how close it was to a bosch 928 alt.So after trying to fix the weak 80 amp bosch that refuses to charge anywhere near the amount of power that I needed to run a/c ,headlamps and electric cooling fan I bought a 40 buck liftime rebuit and mounted it up.First one went almost 100k miles before failure.I'm still on the second one with about 60k so far on this one

BC

I am interested in learning more about this as well, but for later engines. The mounting is somewhat different, with what they call an "alternator console" that also carries the power steering pump. The later alternator is HUGE and HEAVY.

Any info on whether this would work on the 85 and later assemblies?

toofast928

Thanks for the boost SharkSkin, but the real credit goes to 928FIXER as it was his first post that led me to the actual install.

Sterling I did have the Bosch rewound for additional 50 buck. Still overheated and pucked because of the amp load at low RPM.

Rick Carter

I was trying to find a replacement for my 85 but will go with a rebuilt for $180.00 from Advance Auto. If it lasts half as long as the original I'll be more than happy with it.

SharkSkin

OK, I'll give credit where due.

BTW the rebuilder recommends against tying that red cable back to the B+ post. She says it ought to work fine with just the exciter/lamp connection, and that having constant 12V hooked in that way reduces the life of the regulator. It would not be a drain as BrianG suspected, but you would have a circuit energized 24-7 that really shouldn't be. So, my plan is to attempt to hook it up as recommended, and if that doesn't work I may end up attaching a relay to the alternator casing which would, upon being tripped by the exciter circuit, close the circuit between B+ and the red wire on the adapter plug. If that ends up having a negative impact on the exciter circuit then I'll probably resort to running another wire to trip the relay.

There is an optional "Single Wire" setup(differences are internal) which would allow the alternator to function properly with only the big B+ terminal connected(no other wires whatsoever), but that would defeat the charge light on the dash. Such a setup would be ideal for a track car IMHO but is not what I'm after.

Also, I found out that these alternators can generally put out well over 200A on the bench, but are rated 165A to reflect the fact that they are never pushed that hard in the real world -- various limitations apply when installed into a car's electrical system.

While I was at it, I confirmed my suspicion that the 165A unit will run cooler than the 105A unit for any output level(within rating), making the thermo-switch even less of a concern.

Brendan, I don't have the answer to your question, but I will post enough details, including dimensions, so that anyone can figure out for themselves whether the unit will mount up. Is your belt ribbed or 'V'?

BC

I ask because there are real reason to have more power in the system. Imagine two HUGE pumps, one running the Methanol injection system, and anothe running a transmission cooler. What about another one running the Intercooler water? Thats three huge pumps. And another hydraulic circuit for the active wing!

SharkSkin

Yep, you're going to need some juice alright. You're not mentioning the fans that you probably want at least on the IC heat exchanger, maybe on the trans cooler too. Plus you're going to be generating extra heat, which will need to be managed with even more fans. Jeez, any more fans and you'd need an FCC sign-off...

I too have some upgrades in mind -- not as extensive as yours -- but this has to come first. I'd be really surprised if this couldn't be made to work on a later shark. BTW, if needed they can put various size spacers under the pully, or install a dual-vee pulley if your belt is way out there.

Below is a clearer pic of the early mounting setup. IIRC the upper ear on the alternator is tapped 8mm, and there is just the one bolt holding it to the bracket. I think the Delco unit will require a longer bolt and a nut, since the ear is much deeper and is not tapped. Not sure if you have room or not. Do you have a pic of how the later bracket & alternator fit together so we can compare notes?

Warren928

I never noticed a problem with charging on my stock 86 alternator.

I had a few questions concerning reliability and water damage. Being that the AC Delco doesn't have a snorkel input for getting fresh air from a dry place like my stock one does, and the fact that its postion would surely pick up water from the road, wouldn't that cause the following:

1) rusty internals on the AC Delco
2) shorter life, possibly even a short circuit in rain?

I think most of us 928 guys drive them in the rain. I for one had lost my snorkel hose and it was raining hard while I was driving. The first thing I noticed was my voltmeter dropped to 11-12 volts, NOT GOOD!
One the other hand , I dont have an engine tray on my car, but maybe water would still be getting into the alternator even with one.

SharkSkin

I drive in the rain too, though I have a short belly pan that keeps water from hitting the alternator directly -- and I have no intention of being a "U-boat commander". In any case, if you look at the Bosch alternator in my pic the fan sucks air through from the rear, just as the delco unit does. The 130D has two internal fans(and I think with the V-pulley it will have three total) that pull air from the rear and out the front. With or without the snorkel, I expect it to draw air from the dry area behind the alternator. So unless you're driving in a category 4+ hurricane, I don't really think there will be significant water getting into the alternator, or if it does it's highly unlikely it will ever make it back to the sliprings, diodes etc. If you're really worried about it, put your belly pan back on. If that's too big of a PITA consider adapting one of the early, short belly pans for your use. They are cheap and easy to remove/install compared to the later models. Some details here.

heinrich

Heavy rainwater on the road with no bellypan can cause alternator temporary failure, btdt in a 928