E21: Alternator differences

[Ohtwo]

I need an alternator from an E21. My stock 45 amp unit isn't cutting it.
I am told (http://www.bmw2002faq.com/electrical...lternator.html) a 1977-79 320i alternator is needed. When I looked up an alternator from a 1981 320i, it showed a 65 amp alternator isntead of a 55 amp (earlier models).
I would rather have the 65 amp unit, but I am told only the 55 amp unit from the earlier models will fit. What are the differences between the two, besides price and power output? Any mounting differences?

[jbob]

the earlier 320i alternators mounted up high (nearby the coolant branch manifold); the later 320i alternators mounted down low (in front of the oil filter housing). but i believe both alternators are the same dimensions...and should bolt right up to the stock '02 mounting position.

you could also just skip straight to the 80amp alternator from the M10 E30 318i's....you'll need the upper & lower mounting brackets from that car as well. jays323i was selling the brackets & alternator from an 85 318i for dirt cheap last week: http://bimmerforums.com/forum/showthread.php?t=421921

[blitzed310]

Those are the easiest routes. If you dont mind a little bit of fabrication and you got a couple hours to kill. An alt from a 535i will also work, takes only a little bit of cutting and slotting on the upper bracket, the lower one is fine. Its also higher in amps at 90.

You can get them used and shipped for about $45

[Ohtwo]

65 will be plenty, and 55 should do. The 45 is OK, I just feel bad for my battery sometimes. 10 amps is a nice improvement if I understand it correctly.

I don't want to go to a junkyard and start ripping a 318 apart.

I'm just trying to figure out why that website reccomends the earlier model alternator. There must be a reason.

Any idea how many amps it takes to actually run the ignition system? I have an MSD box sitting around, and want to install it, but I hear it puts a greater load on the electrical system.

Thanks for the help

[dmanb55]

I went the Delco route. I'm running an 80 amp series Delco alternator(mid 80's chev half ton) which only requires cutting the small connector and attaching spade terminals to connect to the alternator, some washers and an extra top mounting bracket. I went this route as the alternators for bmws are scarce up here and a Delco can be rebuilt cheap and can also be rewound just as easily to juice it up. Pick your poision. If wiring isn't your thing, cool just bolt on the other things. I know I'll be glad to be able to get a cheap alternator when mine quits.

[waferman]

They are using the 77-79 55A alts because they have a closer matching outputs in back. Also, the body of the 55 and 65A alts are different and the 55A more closely matches your application in your o2.

John
78 320i
83 320iS

[kjhacken]

I'm also running a Delco Alt on my 83' mines from a 89' Astro van with all the fixings and i guess the amp rating comes in just under 110 amps, doesnt seem to have any problems at all powering everything at once, even when im idleing around. Only thing we had to do was shim the lower mounting point and make the upper slider bracket just slightly longer for more belt adjustment room.

Kyle

[mjimport]

I thought I would add info to this thread considering the question was never answered.

I found out why the early model 320 alternators are recommended for an '02 vs. the late models... the late model 320 alternators have a wider upper mount, which will not fit inside the bracket on the block. Also, the outer mount location is too high for the lower bracket arm to reach.

So, for those searching in the future, I recommend going with the 318 alternator if you want more amps, considering you'll have to source a new lower bracket anyway.

[wilfredski]

I thought I would add info to this thread considering the question was never answered.

I found out why the early model 320 alternators are recommended for an '02 vs. the late models... the late model 320 alternators have a wider upper mount, which will not fit inside the bracket on the block. Also, the outer mount location is too high for the lower bracket arm to reach.

So, for those searching in the future, I recommend going with the 318 alternator if you want more amps, considering you'll have to source a new lower bracket anyway.

Thanks mjimport. Does anyone know what works for a 2002tii? I believe the mounting locations are different so does that affect which one will fit? Ideally I’d like the later E21 65A version, or 85A E30, but ideally I don’t want to be fabricating parts. Happy to buy brackets though.

Cheers.

[ascot]

The early E21 alternator works on a tii. You will have to shim the mount on the front housing that goes into the bracket on the side of the block or you can take the bushing from your tii alternator and install it on the E21 alternator.

[wilfredski]

The early E21 alternator works on a tii. You will have to shim the mount on the front housing that goes into the bracket on the side of the block or you can take the bushing from your tii alternator and install it on the E21 alternator.

Thanks very much ascot! Ok, so the early e21 alternator will do the trick.

Just so I know, do you (or anyone else) know what would be required to fit the later model e21 alternator to a tii please? I’m caught between wanting more amps but wanting to avoid too much messing around with fabrication!

Cheers.

[SenorTaylor]

I thought I would add info to this thread considering the question was never answered.

I found out why the early model 320 alternators are recommended for an '02 vs. the late models... the late model 320 alternators have a wider upper mount, which will not fit inside the bracket on the block. Also, the outer mount location is too high for the lower bracket arm to reach.

So, for those searching in the future, I recommend going with the 318 alternator if you want more amps, considering you'll have to source a new lower bracket anyway.

Yup, I found this out yesterday trying to install an 83 320i alternator in a 74 base model 02. The upper ear on the alternator is too wide to fit in the bracket on the block with the regular bushings.

[wilfredski]

I thought I would add info to this thread considering the question was never answered.

I found out why the early model 320 alternators are recommended for an '02 vs. the late models... the late model 320 alternators have a wider upper mount, which will not fit inside the bracket on the block. Also, the outer mount location is too high for the lower bracket arm to reach.

So, for those searching in the future, I recommend going with the 318 alternator if you want more amps, considering you'll have to source a new lower bracket anyway.

So can I confirm please: Is the 318i alternator you’re recommending the 80A BoschAL46X?