Upgrading Alternator in YJ, TJ, XJ

[kirksjeep]

From what I have read this should work for 91+ YJ's, all TJ's and newer XJ's.  Most Jeeps came with an 80 or 90 AMP alternator which is ok for most stock Jeeps, but add a whinch, lights, stereo etc... and the stock alternator is going to have a tough time keeping up.  With some research I found that a 98 ZJ with the V8 came a 136 AMP alternator that only requires a few modiications to make it fit.  My new alternator is sitting on my work bench but it apparently just needs to have the electical connection swapped (two bolts) and may or may not require the bracket to be shaved slightly to compensate for the larger girth of the bigger alternator.

I picked one up from Advance Auto with a lifetime warranty for $144 before a $50 off coupon I had.  There was a $32 core charge, so I gave them back my bad XJ alternator that was sitting on a shelf.   

Most of what I read also says I will need to upgrade the wiring from the alternator to atleast 6 AWG, but I will tackle that after I get the mounting figured out.  I'll post back more when I get into it.

[kirksjeep]

Alternator is in, but I stil need to upgrade the wiring.  Here are a few things I noticed about the upgrade.

1. The electrical connection was simply the one for the positive cable back to the battery via the fuse block.  Removed the nut holding it on with a 10mm socket and swapped it for the stock YJ one.  All this does is orient the connection 180 degrees.  I could have filed off a small plastic nub and flipped it just as easy as swapping it.
2. The pully on the ZJ alternator has one more rib then the YJ.  From what I read, most guys just leave it and make sure it is moved towards the alternator exposing the front most rib.  I took the extra 30 seconds and with my impact gun swapped the pully over.  It technically took a little longer since I gave the old one a coat of paint, the mechanical part only took 30 seconds
3.  I didn't have to do any grinding.  The stock YJ alternator was 4 7/8" wide and the ZJ alternator is 6 1/8" wide.  I imagine this is a YJ thing since the write ups for the TJ and XJ both said they had to grind the mounting bracket.  
4. With the heater fan on high, all the lights on and my 2000 watt stero pumping the alternator was right at 14 amps when the engine was at 1500 rpm.  The stock YJ one would drop to just above 12.5 amps.  
5.  I think my plan is to run 4 awg wire from the alternator to a dual 8 awg distribution block.  From there the stock wire will go to the fuse block and I'll run a second 8 awg directly to the battery. In the sound system world this is a common upgrade.  

I'll post more when I do more work.

[kirksjeep]

Wiring is upgraded.  Based on $ I went a little different route, but I think it works great.  Here is how I did it.
1. I bought a battery to starter wire 4 awg and a battery to ground wire also 4awg.  Both are the GM style ends to go on the front of the Optima.  The battery to ground wire was 24" and the battery to starter wire was 40".  The battery to starter wire is a little long, probably could have used a 36".
2.  Both wires had 16 gauge wires attached to the terminal, so I cut them off and used liquid electrical tape to seal them off.
3.  The only other mod I had to do was to grind the the terminal end going to the alternator to make it fit in the mount. 
4.  The upgraded ground wire goes from the negative side post to the ground on the engine above the oil filter.  The upgraded alternator wire goes right from the alternator to the side post on the battery. 
5.  Results were seen immediately.  With the same power draw I did above, lights, fan on high, and stero thumping.  Now at idle I am a hair under 14 amps at the dash.  It is almost an amp higher then before!