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yet another alternator post


grizzlebar
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Looking at swapping out to a higher amp alternator and seems like it is limited to the following options:

 

Rebuild current

     Pros: Know it'll fit

     Cons: need to find a shop to do it

 

E-Bay special (BNR/Eagle Auto)

     Pros: Promises of drop in replacement, reasonably priced ($200ish)

     Cons: Seems like not everyone is satisfied

 

Rush Power Systems:

      Pros: drop in replacement, quality

      Cons: Pricey (by comparison) $400+

 

Junkyard special

     Pros: need to find all of the parts

     Cons: may require some modification, also may not work

 

Am I missing anything here? Anyone go one route and regret it?

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Perhaps a variant of #2 and #4 but the other option is to buy an OEM alternator off ebay/Craigslist or a BMW forum.  In the case of say, an e30 318i unit, the required additional components are well documented.

 

I bought one and replaced the regulator and brushes for a grand total of $7 (Rock Auto had a sale on Bosch parts).  Had it tested and it is fully to spec.  Also bought an OEM e32 starter off ebay and it works perfectly with no "upgrades".

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10 hours ago, Healey3000 said:

Perhaps a variant of #2 and #4 but the other option is to buy an OEM alternator off ebay/Craigslist or a BMW forum.  In the case of say, an e30 318i unit, the required additional components are well documented.

 

 

this is the way I went.  Back in 2008, when I was rebuilding the engine, the hot setup for alternators was the 84 318i alternator.  Don't remember if it was specifically an 84 but my notes say 84 several times.  80 amps or so IIRC.  What I really recall was the alternator bracket to the block was the difficult item to find.  It took me quite a while before I finally found the bracket.

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I have a BNR,  works great or work as advertised. I find alternators are largely consumable.  I am not sure of the 318 series of alternators, but in terms of bearings, they all seem to just have sleeve bearing, which is not friendly to people that like to spool up their engines.   Also, there seems to inversely proportionately amount of amps you get out of one as opposed to the lifecycle.  In my experience, It is largely due to heat and the size of the components in the internal regulator.  

 

 

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So here's the details from my conversation with Darren of RPS: (its an amalgamation of three emails based on some needs-based discussion)

 

Always good to positive feedback, we have done quite a few of the members 2002s and we do offer a group discount. the alternators we offer are all bolt in, with no fabrication required. However the factory brackets are not consistent, at first we had thought there were two different brackets but it seems there are production issues. So sometimes the alternator requires an adaptor bracket, and we supply one, if you don’t need it you can toss it. The factory alternator is underpowered for the vehicle needs, but it was all they had to work with. for example, your factory alternator will do 5 to 10 amps at an idle. There is a factory style alternator that is a newer Bosch but it will only do about 15-25 amps at an idle. Our alternator is capable of producing up to 70 amps at an idle, but only if the vehicle needs it, it will not over charge the battery. How much power did you need? Or what electrical accessories have you added and I can do the math

You have a limitation in how much power you can run and that is your "V" belts. A V-belt can't make tight turns, we are limited to about 200 amps. When you run a high amp alternator you change the power curve, so to bring it back in line with stock you run a smaller pulley, on a multi-rib belt system we can go as small as 1.5 inch diameter, but on a V-belt we can't go any smaller than 2 inch.

So here is the break down, we assume about 50 amps for the vehicle, however LEDs pull a fraction of the power as standard bulbs, so your needs would be more like 30 amps. Your fan will add 20 amps back into the mix. A fuel injection system will need about 20 amps, so you are at 70 amps. We don’t really add the windows and locks because they are not in use that much.

So with a 200 amp alternator, you are looking at 130 left over for the stereo, so that is 1820 watts. So now we need to talk about how you use it, if you are constantly at low RPM, light cursing, and if you play the stereo at full to 3/4 volume, then keep the stereo wattage below 1300 watts. Another factor is your location, as an alternator heats up it produces less power, we rate our alternators hot but if you are in Texas, your hot can be different from our testing hot. We have a special coating we can apply to the case to help it to run cooler. One final thing to keep in mind, 200 amps is at about 2500 engine RPM, at idle we can get it to about 130 amps, but depending on how many watts you run, you may need to look at an additional battery or a stereo capacitor to fill in any gaps.

 

Plan for heat, so here is what I would recommend, 200 amp alternator with heat reducing coating, install kit that includes the connector and bracket if you need it. the total is $XXX. So the discount would be $XX for a total of $XXX and that includes shipping.

You don’t want to run an alternator at full power all the time, so it is always better to have more power than you need. If your stereo needs will stay quite low, say under 750 watts, you could go with a 150 amp alternator. The same thing in a 150 amp is $XXX so the discount would be $XX for a total of $XXX

The heat reducing coating process takes a week to 10 days but other than that all parts are in stock. Let me know if you have any questions or if you would like to order one, I can send you an electronic invoice for which ever one you select.
 

 

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  • 11 months later...

Update: ended up finding a 318i being parted out and picked up the alternator and brackets for a song. @Healey3000, do you remember which parts you ordered?

 

Also, anyone have a good guide on rebuilding the alternator itself? I'll need to clean up and paint the casing too as it will definitely not match my engine.

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On 10/27/2017 at 11:04 AM, grizzlebar said:

-Bay special (BNR/Eagle Auto)

     Pros: Promises of drop in replacement, reasonably priced ($200ish)

     Cons: Seems like not everyone is satisfied

 

Everyone may not be satisfied but I’ve had no issue with my BNR high output internally regulated Tii drop in for 3 years now

 

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Double02 Salvage https://www.double02salvage.com/index.php used to sell a reasonably priced kit (less than $100, IIRC) consisting of an E30 318 alt (80 or 90 amps) with the lower bracket required to install it in any non-tii 02. Not sure if they still provide that kit, but this is plenty of power for an 02. Even with the 600 watts of stereo amps I have in my 02. I am using LED and HID lamps and other modern components, which cut down the other power requirements a bit.

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