So I have a 1991 4x4 Tracker that im looking for info on some of the newer models with V6's to swap into mine.

Is there any of the later V6s that will bolt up to my stock drive train?
If not is there a adapter kit available any where?

I have searched but havent found if anyone on here has did this type swap..

Lastly is a v6 swap better than just performance upgrades on the 1.6 to get more power?

 BRD HNTR and someone else has done the v6 swap into there tracker if your search his posts there is a big write up about the swap. the wiring to hook up looks like a nightmare and is a tight fit. There is no adapter kit and it would be best to have the donor vehicle or you would be making a lot of trips to the autoparts store or the auto wreckers.
 
The 2l or 2.3l would be a better and easier swap I my eyes. I'm sure BRD HNTR will chime in and give you a detailed explaination

I found this in the diy sectionlook for  Tracker-2x4 rockers-Frnt Bmper-4 dr sprngs-lwered frnt diff-$30 steel frnt diff

Is there any of the later V6s that will bolt up to my stock drive train?
If not is there a adapter kit available any where?

No and no.

Lastly is a v6 swap better than just performance upgrades on the 1.6 to get more power?

It depends on how YOU plan to use the performance.

What is your idea of a "performance upgrade"?  A turbocharger is a performance upgrade - it could conceivably give you more horsepower than a V6 swap - and it would be a blast to drive on the street, but it would probably suck off road,

It is a VERY tight fit.  Follow Beagle's link to my build, and his advise "Get the Donor Vehicle".  You either swap out all of the wiring, or decide where you will merge the wiring.  I do not know of anyone that will flash the computers to remove unwanted codes, so everything has to work when done or you will be running with permanent codes, and some of those will put you in limp home modes.
I love the finished (it is never finished) project, power is great & so is sound.
Wiring is a nightmare, complete change out might be easier for those who are not inclined to spend countless weeks going over, over, and over wiring charts.

The Aerio 2.0-2.3 is a more viable swap, and will produce about 50% more hp than stock.
As Fordem pointed out, putting a turbo on can get you some more hp out of a 4 cylinder.
I haven't figured out just who built the stock transmission for the first gen motors, so do not know what else will bolt up to it. 
It is a tight fit

As a person that has done 4 of the V6 engine swaps, I'd say go for it! The wiring is not that difficult depending on how integrated you want the engine to be with your vehicle. I'd suggest getting the earlier 2.5 or 2.7 vehicles as the electronics did get more advanced/involved after 2003. You'll have power and get about 15 to 17 mpg. So if you have the 2-door gas tank you'll run out of gas WAY before your friends.   So, that's fun too ...

As far as physically placing the components. The stock sidekick t-case bolts directly to the 2.5 automatic transmission which in turn will bolt to the 2.5 or 2.7 V6. The first one I did (mine) I've driven for 10 years or so I guess and it's a 2.7 engine w/2.5 GV transmission w/Sidekick t-case with rock crawler gears installed. I have always had the evap error codes because I never put the newer tank in with the correct sensor but that's it. Use the stock cross member from the sidekick and bolt the t-case w/stock mount to it's stock location as you 'float' the engine with a cherry picker. You can measure and build your engine mounts from that. Drivelines etc.. the same. This only one method of many that could be employed.

Check my Liberty Overland FB page, I've got I think 3 of the 4 swaps pictured there...

The factory service manuals are available here at our main page's library.


Good luck! -Eric

As Eric mentioned being able to use stock Sidekick transfer case is another good reason to go with the earlier years.  The 04 & up years have larger input/output shafts on the TCase, so you are stuck with Suzuki TCase, or possibly Toyota TCase with v-6 adapter.
If you are doing a SAS, then the fit would be much easier.  I had to make oil pan clear the crossmember. 
Yes, It will run with the motor & transmission wiring and about 6 input wires.  Running with a code means you will not know if another code comes in (which is how we ran the race car), and 10 years of running shows the concern may be over rated.
Like Eric, my TCase mount is stock sidekick, and I am only running the center mount as I have dual exhaust in the way of the smaller right mount.  The TCase mount sets the motor position, which is close to radiator.
I run 17-20 mpg on 33's, and could do better on highway if I stay below 65.   At 70 it is ready to move and cruise.

But I would say if you don't have a garage with jacks & stands, grinder, wire feed welder, v/ohm meter, and able to read wiring diagrams, then this will be a very difficult swap to accomplish.  It could be done with less, but not by many.