# MKIV High Output Alternator and Big 3?



## JettaGetUpandGo (Mar 1, 2005)

The OEM 120 amp alternator in my MK4 1.8T GLI is dying. I'd like to replace it with a higher output alternator (180-200 amps). I got a quote from Excessive Amperage for $380 or $420 powdercoated for a 200 amp alternator. Are there any more reasonable options out there that are a direct fit?

That also brings me to the Big 3. I know it involves upgrading the wiring to a lower gauge wire to handle the additional amperage. I'm assuming it's three wires that need to be replaced. Which three are the Big 3? What's the best way to go about replacing them (DIY?) From what I know it's alternator to starter, starter to battery, and I'm not sure what the third is. I'm also not sure what type of connectors are necessary.

All of the archived threads are down and there's nothing related in the recent topics.


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## sgolf2000 (Mar 2, 2003)

BIG 3 

1 alternator to battery(12V fused) 
2 Battery ground to chasis 
3 transmission/motor ground to chasis 

upgrade those wires


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## Pat @ Pitt Soundworks (Nov 14, 2008)

Also check out Ohio Generators or Iraggi Alternators for big alts.


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## JettaGetUpandGo (Mar 1, 2005)

Thanks for the quick replies! What type of connection is on the alternator for adding a lower gauge wire. Is there a post to use a ring connector? I tried looking on my car today but couldn't see very well. There was something that appeared to be a bolt with a rubber cover.


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## Pat @ Pitt Soundworks (Nov 14, 2008)

Mk1's use a plug. Mk3's and up use post and ring. I'm not sure on mk2s.


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## Non_Affiliated (Feb 12, 2002)

That is actually about the ball park for a 200A alternator. 

usually a ring terminal is used on a post off of the alternator for the B+ (+12V) output.


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## JettaGetUpandGo (Mar 1, 2005)

I'll go with the Excessive Amperage alternator then. I've heard a lot of good things about them. My local car audio store should have some flexible 0 gauge wire and connectors relatively cheap. Thanks for the help guys!


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## JettaGetUpandGo (Mar 1, 2005)

Sorry to bring this back from the dead. I finally got around to upgrading the wiring. When I stopped by a local shop they offered to give the me a length of 0 gauge wire for $30 + $9 for ring terminals, or cut the wire to the right lengths and install it for $90. I don't have anything that can crimp 0 gauge wire and I really didn't want to mess with it, so I let them do it.

They did the alt to battery and it's fine, then the battery to chassis they used an existing bolt near the battery tray that was hanging out on it's own (right next to an OEM ground location), then ran another wire from there to one of the main bolts on the motor mount.

I'm not a big fan that they used the motor mount bolt since that bolt head no longer lays flush on the mount. There is a nut for a coolant line on the same piece of metal two inches further, but the wire is too short to extend to there. *Here's my question:* is the battery to chassis and then the chassis to motor mount really necessary? Why can't the wire just go from the battery to the smaller nut on the motor mount since the mount is bolted to the chassis already?

The 200 amp alternator is finally going in on Tuesday. The electrical issues that I was having were fixed with a new battery, so I wasn't in a huge rush to get the alternator in. I'll have to sleeve the wire with something too as the silver wire stands out a bit too much in the engine bay (better than blue though!).

Pictures of what I was explaining:










Note the OEM ground immediately next to the bolt used:










Connection at the motor mount with the smaller nut just to the left:


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