Start slow, like around 4-6 psi and invest in a good wide band. Short of a stand alone, tuning could be a real bear.

 

The superchargers they make for the 4.0 puts out 5.5lbs of boost. The supercharger kits also run over $4,000 If you plan on building the bottom end stronger you could also stroke it with a 4.2 crank. I've seen different stroker kits available between a 4.5-4.7

If you were to build the bottom end up and use lower compression pistons you could probably push 12lbs of boost.

All of this can be done, but it just doesn't seem worth it when you can swap in a Chevy 350 and 700r4 trans, then you could run 4.11 gears with 35" tires and still have enough power and get better gas mileage.

If you already have a turbo setup that you can get to work I say go for it, but I'm thinking 5.5lbs is the sweet spot. If your going to to do that it probably wouldn't hurt to port and polish the head and do a 5 angle valve job, a higher flowing exhaust would help a lot to.

I think the 4.0 is a great motor, it's plenty of power for a stock or mildly built Jeep, and they last forever. I just think it takes to much to make any real power out of this motor.

 

Its a well built engine,im more impressed by the 222 ft lbs of torque @ 2800 rpm that comes out of the 4.0

 

I've boosted plenty of Honda's and 8 psi is about all a stock bottom half can run,I wont last long at 8psi.The same honda running 5psi would last a very long time.I would look into rebiuilding the bottom end before I ran 8psi into any engine.In the Honda world you gain an average of 10 horsepower per psi with a performance intake and exhaust system along with valve work.The 350 swap sounds more reliable and feesible,Just my 2 cents

 

The 4.0 isn't the best to turbo because it has both intake and exhaust ports and manifolds on the same side. If you start to push a good amount of boost into it your going to run into heat issues. The 4.0 is better suited for supercharging weather it's centrifugal or roots style.

 

i have yet to see a same side turbo setup on a 4.0. Everything i see goes under the oil pan and comes out on the passenger side of the engine and there is where the turbo is mounted. I have also seen a setup where the turbo was all the way back behind the tcase lol.

The most i've seen people run on the stock internals and bottom end of a 4.0 is 6 psi.

4.0LSahara, on any turbo setup not just the wranglers, above 6psi you need intercooler

I've had experience with turbo Miatas.. there were people on the miata forum running turbo setups at like 12lb with their engines lasting over 200k miles. I'd hope that our 4.0 with say 5-6psi boost would be more durable than a 4 banger with less than half the displacement and twice the boost.

Now as the turbo vs supercharger debate goes.. A properly tuned turbo will make more power than a properly tuned supercharger at the same boost. End result? Turbo > Supercharger.
Here is a dyno chart of the same miata with turbo vs supercharger. Turbo is running at 12 psi while the supercharger ends up at 13 at the end. That supercharger is the twin screw bts which is the most efficient one on the market today.
http://flyinmiata.com/tech/dyno_runs/2.0_uber_vs_2.0_FMII_GT3071.pdf

Keep us updated man, this is going onto subscriptions!!!

 

ya i'm just saying what i heard about turbocharging the 4.0 I read it from a few places and the heat soak wasn't from the turbo it was from the manifold as boost goes up your going to raise your egts. but at 6 psi i think you should be fine.

 

ya, it kinda makes sense just dropping in a v8. Id probly spend the same amount after gauges, wiring, a stand alone computer, etc. I just thought it would as easy as my supra which is boosting 30+ pounds of boost on a stock bottem end, I guess the 4.0 is high compression. ima put a post about engine swaps

 

high compression? nooooo no no far from it.. 8:1. It's just damn crappy weak.

 

 

Actually, remote turbo's work quite well. A few guys in the Dakota crowd have used them with great results.

 

that jeep better not ever see water cuz that turbo would not have a fun day

 

I dont know jack about turbos but that just seems like a real bad spot to put one...just sayin

 

hehe lets just say turbos rely on hot high pressure gasses to produce boost. What this will do is you floor it, 10 seconds later, boost kicks in. = Extreme lag.

Besides the fact that its going to get trashed at that location.

 

upinar id worry more about you axles and trans before trying to get more power.

this scares me "4" rough country lift 3inch body lift 2.25 coil spacer lift 2" wheel spacers"

 

he has long arms now

 

How else is he gonna fit 38's?:flipoff:

 

yeah he has to update his sig, from memory he switched a ton of stuff back when his front tire flew off

 

but still has 2inch wheel spacers and 38s on mini axles??? having the tire fly off really doesnt suprise me, im hoping the tire didnt kill anyone.

 

No he replaced the stock axles w/ something but honestly i have no idea.

 

My boy has a remote turbo on his Tahoe. It's a very sweet set-up and it sounds louder, for some reason. I'd have to say, anything over 5 PSI without an intercooler is a waste of time. I'm a jet engine mechanic for the navy, and that's the biggest thing we deal with (with compression comes heat).

You can probably run anything from 5-8 PSI without a problem, since the 4.0 Inline 6 has a 9.2 compression ratio. The thing I'd be worried about is pushing too much power and a piston going through the hood. I have many friends that turbo'd Civics and Miatas with 9-12 PSI and they're doing fine.

So, get a remote turbo, with a decently large intercooler, and I think you'll have one of the best TJ's around. Don't go the cheap/easy way and get a V-8. That's soooo played out...:flipoff: