First question - What is the largest stock alternator you can install on the 1999 4.0 xj without upgrading the wiring and being safe obviously.


Second question - What are options for an alternator where I would have to upgrade the wiring but still have it fit with the current bracket system and no modifications?

I've seen the durango 136 and 160 amp unit. I've seen some of the wiring kits also. post away. thanks

 

1) I believe the largest stock alt is 117amp
2) im pretty sure you have to grind no matter what bigger alternator you choose, above the 117. + wiring/fuse or breaker.

 

Some info here that might help you too. From stock through upgrades on what wiring should be changed.
http://www.geocities.ws/jeepi6power/price.html

 

My quest to do this started with the fact the the battery cables in my '00 were not in the best of shape.
Figured they needed to be replaced. Since they were being replaced might as well upgrade.
And hell if we are going to do that might as well upgrade the alternator.

So I started to research it.

It depends on who you believe. There is so much conflicting info out there.
One guy will tell you the '97 or '98 136 amp from a 5.2 GC will drop right in.
Then another guy will say he had to grind his bracket to do it.
Appears the 160 Durango swap you have to grind the bracket.
But then I come across this one post where a guy said he had to grind his block a little.
Can't remember what alternator he was trying to put in.
You see guys grinding the brackets almost always.
Couple grinding the alternator.
Still trying to figure out how you grind the case of an alternator without getting crap inside of it through the vents.

It was giving me a headache researching this.

So here is how I solved the problem. I went and got an alternator that would fit an '00 from the boneyard.
I paid $100 for the alternator from an '00, the ECM, and one of the engine wiring harnesses.
The one with the O2 sensor connectors and fuel injector connectors on it.
The '00 was a Federal Emissions one. We are not going to discuss why I took that stuff.
Wink wink.
So break it down however you want to to figure out what I paid for the boneyard alternator.
I dropped it off to my guy who rebuilt it and upped the amps to just under 155 amps he says.
$140 and it will bolt right in. Should be fine with the 2 gauge battery cable I used and the 175 amp mega fuse to replace the fusible link.
I did the cable upgrade a few months ago. Alternator won't happen till next year. That is when I will swap out the 125 amp mega fuse I run now with stock alternator.

I know that this does not answer any of your questions.
The one at Napa is 120 amp.

https://www.napaonline.com/en/p/RSE2...ndex=Universal

Which is what is in my '00 now.
So drop that in and call it a day.
But when you decide to really upgrade expect the worse but hope for the best as far as any modding you might have to do.
For battery cables see this guy. But do it quick because he is shutting down his side business making them.

https://www.cherokeeforum.com/f73/up...cables-221513/

And if you go my route just make sure the case is in good shape cause they do like to crack.

 

I also think the highest stock output alt is 117 A. You might be able to get an aftermarket alternator (such as a Mean Green) or get a factory alternator rewound that would not require grinding the bracket and put out serious amperage.

In my opinion, you should just go with the biggest you can now. A few years ago I upgraded to 4 awg wiring and a 136 A Durango alternator which required grinding the brackets and a hair off the block. It has served its purpose well for awhile but now I just installed a second amplifier and will be installing a winch soon. I'm wishing I did 2 awg or 1/0 awg wiring and a 160 A Durango alternator because it would've been the same amount of work and not a ton more money.