4 cylinder to 6 cylinder swap

I have been looking around for a cherokee for quite a while now. I dont know too much about cars and stuff like that because I am only 15 but I am very willing to learn. I want a 2 door manual and Im not having a lot of luck finding one. I found a couple of them with 4 cylinders though. Did they make cherokees in the 90s that had 4 cylinders? I was under the impression that they didn't. Now to my main question. Is it easy/possible to swap out a 4 cyllinder for a 6 cyllinder from another cherokee? I read somewhere that you could get newer cherokee engines for about $1200. Would that be worth it.

Thanks for being patient.

Yeah, they came with a 2.5L 4 banger, 2.8L v6 and the 4.0L I-6 which is the 2.5 with 2 extra cylinders. The rod lenght, piston size, cam lobs, valve size are the exact same. Putting in a 6 for the 4 cylinder is a bit**, the motor mounts are different and you need to weld in supports. You would have better luck getting an auto with a 4.0 and changing the auto to manual (if that is your choice of tranny). http://www.stu-offroad.com/aw4/index.htm it changes the manual to an auto, but it gives a rundown of the different parts from auto to manual parts on the T-case. There was a few different 5 speed tranies used in the jeep, unless you get into the older CJ then it came with a couple more choices. for the price of the 4.0 motor you listed, you could find a used jeep and get the parts from the junkyard to swap out trany The cross member on the 5 speed is ~4" further foward than the auto, but the bolt wholes are there. It would require new driveshafts front and rear to do the change. The best years are '91-'95, the HO motor came out in '91 and in '96, they used a different tailshaft on the T-case and you need to drop the trany 1" to reduce driveline vibes, and an SYE (slip yoke eleminator) when lifting above 2".
:repair:

the 4-banger and the 6-cylinder use different transmissions.

get a 4.0L auto and swap in a 5-speed, or deal with a 4-banger.


as far as actually swapping in a 6 in place of a 4, no welding is needed, just swap the motor mount brackets on the unibody, you can unbolt them and bolt the 6-cyl ones in.

HO/Renix 4.0L... neither is better. just different.

the HO has more top end HP, better for cruising on the interstate.

the Renix (87-90) has a flatter torque curve which peaks at a lower RPM. this will give you more pulling power, and, to put it in perspective, a renix 4.0L will beat the 4.0L HO off the line, but the HO will whip the renix before the next traffic light

95+ XJs had WAY better brakes. THIS is MORE important than ANYTHING.

especially if this is gonna be your first vehicle, and stay away from 89-92 models with ABS. they're death traps (Single Channel Bendix ABS) this braking system failed on a friend of mine, damn near killed him too.

How about the '93 ABS system? I have a '93 country and the wife has the '95 SE. Since I plan (once I find the front) to change the axles for 60's and won't need the ABS system (no speed sencors on the 60's). Want to take '95 booster out of wifes and put the ABS axles (297X) and the stock LSD, and complete ABS including the computer, on wifes and take her booster. She has rock hugging 8.25 open, she will loose the strenght but gain a limited locker, and stronger front axle.

I must have been missled :anon: I thought the mounts had to be welded and that the firewall clearence would be a problem if didn't do it. But that must just be on the pre-'87. Maybe, don't know.

Where

Where are you located. I have a 2 door manual 2.8l v6 here in Colorado that is looking for a new home. I was going to use it to put my 4.0l stroker and tranny in but found a newer model with a fried engine. We're talking less than $500.

Just to clarify an apparent discrepancy between what M. Lake posted and what CheapXJ posted:

I know that CheapXJ has recently completed a 4-cyl to 6-cyl swap in an MJ, so he speaks from experience. However ...

Keep in mind that the 4-cyl was used from 1984 thru 2000. The 4.0L I-6 was not introduced until 1987. The engine compartments in any 1987 or newer XJ or MJ will already be set up to accept a 4.0L -- no welding necessary. The engine compartments of the 1984 thru '86 XJs and MJs were configured to accept an I-4 or a V-6 -- those are the years that require fairly major surgery in order to make a 4.0L engine fit. It can be done, it HAS been done, but it's a lot of work that's completely avoidable if you are looking for a vehicle rather than dealing with one you already own. Just buy an 87 or newer and there's no problem.

BTW, I would not discount the lowly 2.5L 4-banger. It's a very good engine, and for most purposes other than drag racing or heavy towing will be more than adequate. And it can be tweaked to produce a lot more power than stock -- all those truck races Jeep won with the MJs in the early 90s were running the 4-cyl engine.

CheapXJ- so what you are saying is that it is possible but I would need a different transmission? If so, would that be very hard/expensive? I don't even have too much money yet but by the time I do, I hope there will be a cherokee like I want.
Also, is it simple to change from auto to manual? Are there any benefits from putting in my own manual transmission over a stock manual transmission?

Thanks for the help.

Learning curve.

:doh: I was close, I knew that there has been discussions of the engine bay modifacations, but was forgetfull of the years. With having the HO 6, I don't have much need for the knowladge, but tried to bring up old memeries.

The 4 and 6 banger AW-4 tranies are different, but don't remember exactly how. Either the imput gear, or the strengh, both as for as I know.

If you get your hands on a 4 banger and decide to go for the 6, you will need more then the motor, ECU, and harness will need to be hunted down. Best bet would be a bone yard. Or give it a month or two and find the jeep you will be happy with from start. Jeeps are built not bought, but a good foundation to start with helps.

vbjornsson, you came to the best place for info. I am a member of a local state group, and a strokers group, but this group has all the info you could ever learn. Pitch, toe, roll, pinion angle, squat. These guys have all the #'s and come up with things not seen anywhere. Stick around and you will see what I mean and what all that stuff is.

Jeep Tranies scan down

vbjornsson said:

CheapXJ- so what you are saying is that it is possible but I would need a different transmission? If so, would that be very hard/expensive? I don't even have too much money yet but by the time I do, I hope there will be a cherokee like I want.
Also, is it simple to change from auto to manual? Are there any benefits from putting in my own manual transmission over a stock manual transmission?

Thanks for the help.

Click to expand...

You could use just about any transmition you want. Conversions Can come up with quit a few conversions for just about any motor, trany, t-case combo you could think of. The jeep XJ (most years, u/k early years) are interchangeable, the parts for the pedle and the hole for the stick is in the body either auto or 5 speed.

The crux of the tranny problem is that the 4-cyl uses the same small bellhousing-to-block bolt pattern as the old GM 2.8L V-6 that was offered from 1984 thru 1986. The 4-cyl used that bolt pattern right to the end of the XJ in 2001, and still uses it in the Wranglers. The 4.0L uses a larger bolt pattern that was the old AMC V-8 (and I-6) bellhousing bolt pattern.

So it's more than just spline count -- that's more of a problem of mating the tranny to a transfer case. The first problem is bolting the tranny to the engine.

For automatics, the 4-cyl used a Chrysler tranny -- 904, I believe. The 4.0L uses an Aisin-Warner AW-4. For 5-speeds, the 4-banger used either a T-5 or an AX-5 (T-5 was in the early years when they ran low on AX-5s), while the 4.0L depending on year used a Peugeot BA 10/5, and AX-15, or a NVG 3550. Even if you can find (or make) an adapter, it's not likely that the AX-5 would hold up for long behind a 4.0L.