hans14914

I have been talking to one of the best alternator winders i know, about the lousy output of my stock alternator. He made several recomendation, including rewinding the stock unit, or he would fabricate a bracket for a large housing gm alternator casing to install in the factory alternator mounting points on our cars. Here is the breakdown of possibilities.

Stock alternator:
160a
180a

GM with porsche mounting flange:
220/160
240/150
260/140
280/130
300/115

On the GM's the second number indicates the output at 750rpm or idle. The pricing would depend on the ammount of people interested. If only one was ordered, to rewind the stock alternator would cost between $350 and $400 depending on the rating, and the gm would cost about $400 for the 220a and run up to $500 for the 300a. If going the stock route, the price includes a new alternator, you dont have to send in a core. Is anyone interested in upgrading? Thoughts, suggestions, and input on both the project and the pricing would be great.
Thanks
Hans

heinrich

Hans since my alternators are working fine it would be hard to justify a 4/500 dollar replacement for my 2 928's ... a thousand dollars I don't really need to spend .... What would this gain us?

H2

Is there a chance that a non-standard alternator output (i.e., much higher than orginally designed for) could fry something on the 928? But the idea intriques me.

Harvey
'85S

MikeN

I guess my first question would be why? Except for early 928s the alternator output seems to be just fine. The first thing I would make sure of is that the stock alternator is in good shape, check all connections and grounds, that battery is in good condition, and that there are no erroneous drains on the system. Unless your car is heavily laden with aftermarket electrical equipment, a properly functioning stock alternator should be fine.
Have owned an '87, '89, and '90, and stock output has always been fine.

928FIXER

I've been using a small case GM that fits right in the mounts and uses the facorty lower bracket and adjuster,the only addition to make it fit is a washer behine the upper mount.These units but out 120 amps at just over idle speed and are cheap and can be bought anywhere if it goes down on a road trip.I get 4 to years of use before having problems with them and just warranty it out at my local parts store.

hans14914

There would be little advantage to an uprgraded alternator on a stock 928. I am involved in car audio, and have had problem installing a stereo in the 928 becuase of low ouput. I couldnt even get 1 alpine 3558 (40wx4 "class a") to run in the 928. I was just looking for a reasonable upgrade, and seeing if anyone else was too. I may try 928fixers suggestion, and play with a small case gm first.
Thanks for the comments and suggestions.
Hans

mspiegle

i'm interested, but at hopefully lower GB prices. I have some big plans for audio in the car.

BC

I think its a great idea Hans, but my S4 needs so many pieces to be put back together before I would dive into this GB - can you check back when you have gauged interest and have more info - or is this the final offer?

For the idea of frying anything, I do believe the regulator would kleep 14v going through at all times, and not fry anything, right?

I will using a Coil near plug system, with sequential ignition, so I am not sure if my draw will go up or down with that - but I will also be adding some fans and pumps - so I am a prime customer for SOME sort of increased power production.

2V4V

Brendan,

CPP will result in a bit less draw to the overall electrical system - depending on the output of your coils of course.

Hans, Mspiegle,

Have you looked into adding an isolated second alt for the audio? Just curious. IIRC, it's a PITA, but I have seen it done.

Also, I can get Bosch alts up to 300 A - but they ain't cheap ~$500-650 each.

Greg

hans14914

Yes, the voltge regulator would limit the output to about 14.4v, which is normal opperating voltage for most cars. I know that the price seems high on these, and it is. But, these are hand wound alternators, and the output is actual. If you get a 300a alternator off the shelf, chances are it will never put out more than 280a. I too would like to get more power cheap, and this is just a first stab at it. I think that one beefy alternator is the best way to go, vs a seperate one. I have found a secondary battery i plan on using for audio, http://www.batcap.net/Model800.html it is a lightweight sealed battery with the equivalent of 800cca. The salesman that i spoke with, was running one in his car as his primary battery, so those into racing may also want to look into it, as it weighs about 10lbs.
Keep the ideas and comments comming, hopefuly the rennlist thinktank can get us equiped cheaply.
Thanks
Hans

Alan '79 928

928 Fixer - Could you give the part number for the GM alternator you are using? I want to try it on my car. Thanks.

Old & New

hans,

I think you may find that a secondary battery is all you need to power your amps unless you intend to exceed ~1000 watts RMS continuously!