Anyone put a newer 2.4L OHC into an XJ?

I am thinking about whether to purchase a friend's 1994 2.5L 2WD 5-Speed to use as a daily driver for some decent fuel economy. (I know, if I really want good fuel economy, I should drive a compact car, but I *like* XJ's)

The 2.5L has 265,000 miles on it, so I think the little 4 cylinder is probably about used-up. 265,000 is a lot of miles to put on a 4 cylinder.

So, I am thinking of possible engine swaps. I searched the forums. Has anyone put in a newer 2.4L OHC Power Tech I-4 into an XJ? Donor vehicles could be 2003 and up Liberties, Wranglers, and 2007 and up Patriots, Compasses, or Calibers.

Will a 2.4L OHC fit under the hood of an XJ, given that the engine is taller?
And I suppose I will have to move over all the electronics, ECU, and wiring harness.

Just wondering whether it is worth putting in the newer 2.4L OHC?
Maybe I should just go with short or long block 2.5L MPI like OEM.

the Patriot, Compass, Caliber use a different 2.4L, its a "World Engine" vs. the Wrangler/Liberty 2.4 which is similar to the P/T Cruizer/SRT4 Neon engine but with a different block for lateral positioning.

hot_rod_hooligans said:

the Patriot, Compass, Caliber use a different 2.4L, its a "World Engine" vs. the Wrangler/Liberty 2.4 which is similar to the P/T Cruizer/SRT4 Neon engine but with a different block for lateral positioning.

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Thanks for pointing that out. I guess that narrows my choices of a donor vehicle even more so to a Wrangler or Liberty, - vehicle with a lateral engine.

Why not try the 2.8 or 2.9 liter chevy 4 cylinders just for some more power with the an efficient DOHC design? If it has the traditional GM 60 degree bellhousing, then your current ax-5 will bolt right up (but may blow up). I dunno... I'll do some researching.

Another cool idea is taking the block from a 2.4, then swapping the head, manifolds, and control system of the turbo PT on. Not sure what the bellhousing is, but I know the NV2550(or something like that) behind the 2.4 is more stout than the ax-5, but not entirely desirable.

and who's to say the 2.5 isn't still in good shape? Same design as the 4.0, 4.2/258, the earlier 232, and every other I-6 made by AMC, but with the middle two cylinders removed. Every one of those is known to be bulletproof, the 2.5 isn't too far off. Mine blew its' #2 rings because of poor prior maintenance, then me using alot of engine treatments to clean it, then running it too hard after. It still hasn't totally given up, even after running on three cylinders and a broken control system for FAR too long.

I'm in a little over $1000 on a performance rebuild 2.5 (including the purchase), and $700 on a newer MPI control system to replace my broken TBI. I consider myself INSANE at this point, but also hope to get a good 140HP/160ft/lb tq, all with Jeep OEM stuff (except for the pistons/cam/lifters). After I have it broken in I think I'll get myself an RVOB4 cam to open up the valvetrain some more.

After all this work, I still want efficiency more than power, I fully expect to get 22city/27hwy, which is just a bit better than what I got after first buying the jeep (and subsequently breaking the engine/control system).

IIRC the 2.4 in compass/patriot is Mitsubishi

I wood just look for a newer XJ with a 4 banger. Switch engine in a XJ will seldom pay for it self in the long run. How if this is just something to do this winter then go for it

Hi Mr_Random,
The family of new in-line engines from GM just released a few years ago, the Vortec 2800 I-4, the 3500 I-5, and 4200 I-6 look like an excellent family of engines. I agree the 2.8L I-4 is a great engine, at some 190 HP and 190 lbs-ft. of torque. I have often thought about how great an XJ would be with a GM 3.5L I-5 or GM 4.2L I-6 within it. A stock GM 4.2L I-6 puts outs close to 300 HP and 300 lbs-ft. of torque. That is in the range of a extreme stroker based on the AMC/Jeep 4.0L expanded to 4.7 to 4.9L. It does seem like a GM 4.2L I-6 might be a more cost effective solution than a stroker based on a AMC/Jeep 4.0L. However, there is some question about how well a GM OHC will fit in an XJ. And the engines are not very common yet, having been available only for a few years so far in some GM trucks and SUV's.

I am thinking that if it turns out that during the bail-out and restructuring of GM, if GM buys Chrysler/Jeep, it would be great to see some of the GM in-line engines in the Jeeps. I think I would rather have a GM OHC 3.5L I-5 over a Chrysler 3.7L V-6 in a future Jeep.

badron said:

I wood just look for a newer XJ with a 4 banger. Switch engine in a XJ will seldom pay for it self in the long run. How if this is just something to do this winter then go for it

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That is good advice. I too have been thinking that the marginal increase in fuel economy of the newer 2.4L OHC over the older 2.5L MPI is hardly worth the cost and effort of changing engines. Moreover, the 2.4L OHC appears to be sufficiently rare, that a guy may have to pay a premium to get one. Probably the best approach is, as you advise, I should just keep looking to find an XJ that has a 4 cylinder, 2.5L, 2WD, 5-speed with less than 125K miles on it.

I have heard of people putting 300K miles on the AMC/Jeep 4.0 I-6. But I would think that the 2.5L I-4 would only last maybe 2/3 as long, being only 4 cylinders and having to do more rpm's to cover the same distance.

Orson_Yancey said:

Thanks for pointing that out. I guess that narrows my choices of a donor vehicle even more so to a Wrangler or Liberty, - vehicle with a lateral engine.

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I meant to say a Wrangler or Liberty with a longitudinal engine. Probably bolting up (bolt pattern) on the bell housing flange is a lot different between a longitudinal vs a transverse engine.

When looking at a replacement for the 4.0, don't look just at the HP numbers - look at the torque / power curves.
The 3.7 they put in liberties is rated 20 HP higher than the 4.0 ever was - but you have to wind it to 5K to get there....
I'm guessing most of the 4 banger options are the same and would yield undesirable results when swapped to the XJ. Unless you like the sound of four chipmunks being whipped into a froth...

GM has had several issues with the 3.5 I-5 and the 4.2 I-6. The 3.5's have issues with leaking valves and porous head casting allowing coolant to seep through the aluminum of the head into the combustion chamber. The 4.2 on the other hand has had less issues mostly consisting of head gaskets.

Hmm. No godlike reliability in the GM inline family like we've got in the 4.0... Oh, well. Still might be worth it to gain ~100 horse / 80 ft lbs in a geometrically similar package.