4.0 head swap

[dirtjunkie99]

Ive got a 1990 model i-6 in my newest cherokee. Ive owned 2 99s and really miss the power they used to have. The jeep is stock right now and i was wondering if maybe putting a newer model head, intake, and tb would wake it up and also what else would have to swapped..

[j99xj]

Your 90' I6 really shouldn't be that far behind what a '99 would put out.

Except above 4000 rpm or so.

Maybe you should look into just rebuilding the engine with new rings and a ported head, and keep the stock intake and throttle system.

You need to understand that even though 4.0 engines are very reliable, when they get old, they simply won't have the giddy up they used to.

[Dr. Dyno]

If you're going to rebuild the engine at all, you might as well make it a stroker. The extra torque that you'll get from the bigger displacement will definitely satisfy your need for speed.

[dirtjunkie99]

OK... well my motor only has about 125000 miles on it, so... Ive heard of ppl strokin the I-6 but never really looked into it. 1st I guess is how much does it cost & 2nd is it really worth it?

[seanyb505]

It depends on how much you want to put into it. Ive heard of people doing it for just under 5 or 6 hundred, but youll probly want to put a little more into it. Chances are if you only want a little more power, your craving wont be satisfied until you have about 5 or 6 hundred hp. So to answer your question of is it worth it, yes. Most definately yes.

[Flash]

Rebuilding a 4.0 is cheaper then building a stroker.....But, if you need to turn your crank, might as well buy a reground stroker crank(258 crank)

the only extra cost would be a set of 258 rods

You could buy your self a plug and play stroker(one already built) you just install it, in replace of your stock motor.(this is the simplest, but one of the more expensive routes)

[Dr. Dyno]

OK... well my motor only has about 125000 miles on it, so... Ive heard of ppl strokin the I-6 but never really looked into it. 1st I guess is how much does it cost & 2nd is it really worth it?

How much it'll cost depends on how far you want to take it. Maybe these stroker "recipes" on this page (http://www.jeep4.0performance.4mg.com/stroker.html) of my performance site will whet your appetite.
When you've finished drooling, you can read my stroker build-up (http://www.angelfire.com/my/fan/stroker.html) to see how you can build an engine that performs even better on the road than it does on the dyno.

[1bolt]

The non HO 1990 is definitely putting out very noticably less HP and torque, My 89 MJ has a fresh Jasper Engine in it (still renix) with 20k miles and it's considerably less powerful than the 147k (Reman'ed at some point but don't know when) HO in my 92 (now mostly parted out) XJ.

The difference between either of them and the 4.6 is also another considerable step up in power.

A well done stroker puts out very similar HP and torque to a 90's 5.0 mustang. The 5.0 or 289/302 SBF has always been a low torqer. Just like the stroker. I can tell you my 87 and 95 5.0's were very comparable to my XJ's stroker. My XJ has 33's and 4.58's and it would have smoked my 95, off the line. Though my 95 was a 'Vert (Heavier than an XJ by a couple hundred pounds), and 95 was the 5.0's worst year ever for wheel HP.

The stroker has a MUCH flatter Torque curve, and less higher RPM HP, but overall they feel pretty close.

Is a stroker "worth it"? If bolt in, late model small block power for relatively cheap (while keeping all stock drive train) is good enough for you then it's EXTREMELY WORTH IT. I love mine! Breaking 33" tires loose is fun :) But If you need 500 HP to put a smile on your face then Spend the extra money, and a LOT more time swaping a V8 (+ drive train and wiring harness, trans, TC etc.) in.

[Dr. Dyno]

Even with all the mods that I've done so far on my 5.0 Stang (and it's noticeably quicker than stock), my 4.6 XJ would still smoke its ass off the line. You're right about the flat torque curve. Take a look at mine.
_____________________________
1992 XJ Laredo - 4.6L Stroker - 5-speed manual
Dyno (http://www.angelfire.com/my/fan/HP_TQ.jpg) - 198hp@4650rpm, 254lbft@3550rpm (wheels) = 245hp@4800rpm, 306lbft@3550rpm (crank)
Performance (http://www.angelfire.com/my/fan/XJ_Performance.htm) - 0-60 = 6.2, 1/4 mile = 14.78@93.7 in full street trim
Sites - Jeep 4.0 Performance (http://www.jeep4.0performance.4mg.com), 4.6L Stroker Build-Up (http://www.angelfire.com/my/fan/stroker.html), Dino's Jeep Tricks (http://www.angelfire.com/my/fan/)

1995 Mustang GT (http://www.angelfire.com/my/fan/Mustang1995GT/Home.html) - 5.0L V8 - 4-speed auto
C&L 76mm MAF|Summit Racing 75mm TB|FRPP 1/2" manifold spacer
Gutted cats|2.5" mufflers, MSD cap/rotor|Taylor plug wires, EGR/AIR delete, FRPP 3.73:1 r&p

[OCMI_Teddy]

Holy shizzle I didn't know you hit 6.2 in that. NICE!

[1bolt]

Even with all the mods that I've done so far on my 5.0 Stang (and it's noticeably quicker than stock), my 4.6 XJ would still smoke its ass off the line. You're right about the flat torque curve. Take a look at mine.


Yeah as you know, a few more mods and your 'stang will be leaving the XJ behind easilly a Cam, and GT-40 or Cobra Upper and lower intake bigger injectors and MAF, Wicked flowing aftermarket heads, the fun doesn't stop until your wallet says uncle...

I wish the 4.0 had the a tenth of the aftermarket of Mustangs. We'd have those roller cams and lifters already :eeks1: