Slave01

New guy to the Forum here. 15 year 928 owner. I recently purchased and installed the 928 Motorsports alternator upgrade kit. It was the easiest project I've ever done to this car. The kit, the instructions, the power of the added amps, it all worked. It went together so well I had to triple check to see if I had missed something. The most difficult portion of this procedure is removing the original factory alternator. As for the power output; primary and secondary electrical component operational improvement is quite noticeable: fans, windows, starter, battery charge. Weight savings felt like around 15 lb. I should have done this 14 years ago.

1988 S4

Koenig-Specials 928

I thought their light weight alternator was only for competetion and rated at only 60 amps

Bill Ball

Carl's high output alternator. Not sure about the 15 lb savings but it does look smaller than stock.
http://www.928motorsports.com/parts/alternators.php

eijun

an alternator upgrade would be only after I upgrade all the wirings in my car

Speaking of wires I am kinda worried about rats in my area, maybe I should move it to my next thing to do after I do an interior cleaning.

Carl Fausett

Fred, we have more than one alternator option. You are right, at 60 amps, the competition alternator is meant for a very stripped-out race car. Little more than the ECU/EZK and the fuel pump.

What we are talking about here is our 200 amp alternator upgrade - here is a link:
http://www.928motorsports.com/parts/alternators.php

Power for all your stereo, cell phone and navigation installations and then some. A real nice upgrade. The alternator the car should have had to begin with (but the technology didn't exist at the time).

Koenig-Specials 928

Trust me Carl I know about this alternator. Its on my wish list. However, I did not know it was that much lighter.

69gaugeman

It certainly is Porsche priced.

blazing928

just wait till it fries itself sitting in traffic pumping out high watts with no air flow cooling the diodes. BTDT

and before I get flamed, I had asked that question re cooling before purchasing as that alt pulls air from the front, so you can't us the 928 cooling hose for the Bosch units , as that pulls cold air from the wheel arch into the rear of the alt. Of course the answer was she'll be right, until it died and was told that was why - i needed a cooling hose????!!!
unfortunately I cant get any parts for it in Aust.....nice shelf ornament

j.kenzie@sbcglobal.net

Mine worked great for about 5 years. I sent it back to the manufacturer, Mechman. It's in Knoxville, Tennessee. They rebuilt it for the cost of parts, their lifetime guarantee. Cost less than $100. Very good service. I know shipping from Australia is a problem, but the service is there.
Good luck,
Dave

Carl Fausett

I agree, Nigel. Send it in and let me have it fixed for you.

I can send it back as a warranty repair item so you shouldn't have to pay import duties again.

Are you sure that heat was all that was going on? Because they can toleraste higher temps than the OEM unit and no, they don't require the cooling hose. All alternators benefit from cooling, this one too, but I have run mine for 5 years with no cooling hose no problems, and many others as well.

Check your system for high loads and shorts in the wiring too.

blazing928

when mine died over three years ago it was my fault for buying a 200w alt to power my car's audio system that has nearly 2000watts of car stereo amps installed.
I was told point blank it most likely over heated in traffic with the amps drawing current [never drawing that much power as the system never gets even close to full volume] with a/c on etc - so too much load at stopped or low speed where the alt did not get enough cooling from air flow .

I was that this was the first failure you'd had of one of these 200amp alt, you had no idea of the cost to fix and it was never going to be a warranty claim- this was never mentioned.

The best commercial decision on my part was to install a 130 amp Bosch alt with the cooling hose, as surely even if I could get it repaired the same issue would happen again.
Perhaps when it is only powering a std cars electrics it can cope with the heat loads. YMMV

eijun

I thought an alternator wont die from having too much draw being it only charges from the belt running (likely your battery will die instead) so I am going to guess either it died from the heat or just a bad batch (or both)

blazing928

Heat

fried diodes, burnt to a crisp, not enough cooling

928MS makes some great products, i have quite a few on my car, but in this case high load at low speed or stopped in traffic [it gets Texas hot here]= alt gets too hot .....

Carl Fausett

I'm not sure any alternator could withstand a 2000 Watt draw at idle speed for any extended period of time.
At idle rpm, that cooling fan on the alternator isn't moving much air.

What do the guys with huge stereo systems do? Increase the rpm's at the alternator? Increase the idle speed? At a car show I noticed some of those mega-stereo cars had fitted two alternators.

Alan

I think You mean it was a 200A alternator. So 200A x ~12.8v = 2560W.

I use 12.8v because thats about the voltage you need to ensure you are actually supplying from the alternator and not from the battery.

Now this 12.8v isn't the set-point voltage (its higher) and 200A isn't the alternator current spec at idle but at higher RPMs. So maybe at idle its only perhaps half that current. Still unless your amp is maxed out for power you should still have had enough supply for typical use.

Alternators get hot due to external effects: high ambient temperature (hot engine air), radiation (e.g. from headers/manifolds) conduction (to the case from the block). They also get hot from internal effects: bearing friction, self heating of the stator phase windings, commutator/brush friction, self heating of the regulator & the field rotor windings and self heating of the rectifier diodes. The rectifier diodes are the biggest internal heat source. A 200A alternator at full power is dissipating about 400W directly into the rectifier diodes. With good airflow this can be cooled. At idle - especially when all the other external effects are high (after a high speed run...) there is massive heat soak, and quite low airflow. When that airflow is already hot - cooling is very compromised. This idle mode is always a challenge for any alternator.

If it does get too hot the general idea is that the regulator compensates by dropping the output voltage to reduce current flow (most of us have seen this...), small voltage changes around 12.8v can change the alternator current significantly as the battery kicks in to supply instead.

I think an ideal configuration for a 982 might be to remote mount the rectifiers / regulator with electric fan cooling. I don't think you can really buy anything like that off the shelf.

Alan