5.2L Swap into a 91 XJ??

Well forgive me guys if this question has already been posted, but I've searched and haven't came up with anything so.........here we go!!

I have a 91 XJ with the 4.0 and I'm thinking about buying a 5.2L and auto tranny out of a Grand Cherokee to swap in there. Keep in mind this thing isn't really street legal anymore so I'm not to concerned about some of the electrical, emissions, etc. All stock gauges are going to be eliminated. Also if you guys are wondering why a 318 instead of a 360......well basically I can get the motor w/ 103K miles, freshly rebuilt auto, T-case still in a 97 Grand Cherokee for $600 bucks. So that means I have all the wiring, computers, etc that I should need to do the swap.

The body is completely gone, the whole thing is tubed and I have a TON of room to work with up front. The only thing left of the body is the firewall. Now my question is, has anybody done this swap and if so how big of a pain in the butt is it to do? I can weld and fab like no other so that part shouldn't be a problem.

The main reason for wanting to do this swap is for a little more power, the 4.0L does ok, but it'd be nice to have a little V8 grrrr to it!! Something about a rig on 40's with a 6 banger just doesn't seem right!! LOL

So if you guys could lend me some advice or steer me in the right direction I'd greatly appreciate it.

The 5.2 doesn't have just loads of power more than a 4.0. It would be a PITA imo just gear it.

With 40 inch tires I'm going to assume you do nothing but crawl rocks and that your rig is towed to the trail.

A 4.0 is a very powerful engine compared to what I've seen on rock crawling tv shows. If its geared correctly it is plenty powerful in my opinion.

There are a lot of serious rock crawlers that use very small engines. On tv I saw one with a 1.9 liter Saturn 4 banger, and one with a 2.4 liter Toyota.

When a vehicle is used for nothing but off road purposes where walking speeds are used, you don't need a powerful engine, or a torquey engine for that matter.


In your case, a 4.0 with 4.88 gears will "feel" roughly the same off road as a 5.2 with 3.55 gears provided everything else is the same.

I have a 4.0 on 39.5 iroks and geared 5.13's . Everyone seems very impressed about how my engine performs. I can spin all 4 on the pavement or on the rocks, so really what are you looking for. I believe the sound of the V8. I love the sound, but is it whats best, probably not. Just my 2 cents.

the hardest engine to swap into a jeep....is a jeep engine.

you would have a much easier time with a SBC or something similar.

my .02

-Tim

It's not the physical engine swap thats the hardest it's the harness but you said you will be stripping the factory dash so I imagine it will all be coming out. You will need the ZJ's ECU and a good portion of the harness so the fuel injection will work, the 4.0 harness won't do it.
I don't know how you will work the gauges though, the ECU needs the sensor imputs so you would have to figure out the gauge hookup inside or start tapping and threading holes for dual senders, one set of the computer and the other to drive a set of stewartwarners or vdo's.
From all I have read and seen, 4.7 or 4.9 stroker is the way to go, gobs of torque and power for what you want. Thats bascially a matter of assembling it on a stand at your leisure then with that big open front of your caged XJ a quick 2 hour swap, almost plug an play. Good luck on whatever your decision. maybe if you can salvage the ZJ's gauge cluster plus the internal harness and somehow fit that in you would have the gauge problem licked.

Yeah this thing is strictly trailer only as of right now. The main reason I was thinking of swaping to the V8 was because my 4.0 is getting a little tired and figured if I could get this V8 for next to nothing it'd save me some cash.

But I do totally agree with you guys it won't make much more power than the 4.0......cuz I'm running 5.38 gears right now with 39.5" Irocks. I was mainly looking for a tad bit more juice and the V8 sound.

I was just trying to make up my mind whether this was going to be more of a pain in the butt than it's worth.........it's kinda sounding like it!! The gauges won't be a problem as I'm not looking to keep anything factory, everything is going to be aftermarket. I don't think I'm going to even run a speedo, just a tach and the usual oil pressure, water temp, volts, etc. The only thing I was kinda worried about was fabbing up the motor mounts.....not sure how hard that would be. Could I cut them off the Grand Cherokee frame and swap them over......or would it be easier to make new ones?

Maybe I'll just stick with 4.0 for now..........but if you guys have anymore input I'd love to hear it!! Thanks guys

As far as the gauge issue goes, you will still need the factory senders if you use the factory ECU, it uses them to control the FI. Then you have to figure out where to tap for the visual gauges that you want on the dash. If you could get the inside harness and cluster then you could use that by fabbing up a housing of some type to hold it, waterproof and sealed box. Have you ever seen an XJ with no dash ? It's got alot of room so your options would be fairly open with all that realestate, elinination of the heater/ac box, etc.
The oil pressure you could T off the stock sender, tach off the distutor unless you can find the tach output from the harness [should not be hard] and drive an another tach. Water temp might present some problems as to where to put another sender [remember the stock sender tells the ECU when to come out of cold loop and lean the fuel out once it reaches that 180F temp].
I have no idea what is available aftermarket ignition wise to control the injectors and mixture though there has to be something unless you convert it to a throttle body injection system which would mean an aftermarket intake manifold unless you can block the multipoint ports with plugs of some sort.
I know a few on blue mountain jeep alliance have considered this swap into both newer YJ's and TJ's but abondoned after actually laying it out but then there are others like AEV that put hemi's in TJ's, maybe call AEV and ask them if they have a custom harness of some kind or Painless wiring might have something. Just trying to come up with ideas.
A 4.9L with a supercharger though, that to me would be sweet, maybe with a nox tank

Wow good points man......I didn't really think of the electrical much but now that you pointed all of that stuff out it is kinda looking like it's going to be more a pain in the butt than it's worth.

The last thing I want is a dang electrical nightmare.......maybe I should just throw in a Ramjet 350!!! LOL

Gotlift01 said:

Wow good points man......I didn't really think of the electrical much but now that you pointed all of that stuff out it is kinda looking like it's going to be more a pain in the butt than it's worth.

The last thing I want is a dang electrical nightmare.......maybe I should just throw in a Ramjet 350!!! LOL

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If you can get the ECU, both internal and external harness and gauge panel it should be pretty doable. I mean it's not like you will have to deal with alot of body sheetmetal in the way or anything... The only other issue that pops into my head is if it has one of those security keys, at that point you will be needing the ignition switch..., what do they call it 'sentry system' or something...