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5.9L engine swap!


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I know this isn’t a mj question, but I don’t feel like joining another forum to ask this especially when I know there are folks on this one who know the answer to my questions.

 

Well first of all I want to say don’t give me too much flack about this, but I want to put a 5.9L in my xj! I was going to stroke my 4.0l but my overhead display wouldn’t be correct any more. ( that may not sound like a good enough excuse but I really like that thing). So if I'm going to loose that I should at least put something in there thats going to make some real power! No doubt that the strokers make a lot of power but all I would have to do is put a cam in the 5.9l to make the same. I have a 5.9L out of a dodge ram in the shop so I was thinking of using it. I would use megasquirt for efi. But I do have some concerns about the transmission. I have a 98 xj classic 4.0L auto. I can't remember what the transmission is I think it’s a 42r-something. But would I have to do a shift kit in it or would the transmission still shift with out the jeep computer running the engine? Or would it even bolt up to the 5.9L, I'm pretty sure it will though? I know a lot of yall are thinking that I will have over heating problems, I plan on getting an aluminum radiator for this. Heck if those Dakota pickups and grand Cherokees can run 5.9l why can an xj or mj?? :dunno:

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The tranny from the XJ will not bolt up to the 5.9, as AMC and Mopar have a different bell pattern, even though they are both round. Your best bet for this project would be to get the rest of the powertrain from a ZJ, along with the engine harness. The only diff. betweeen the 5.2/5.9 harness is the comp. You might be able to use the comp from a Dodge Ram without many/any issues. You also end up with exhaust manifolds that should fit inside the framerails, plus "stubs" hanging on the manifolds to start your new pipes. Not to mention an acc. drive that is fairly compact, with all the acc. closer to the engine, since the ZJ has a smaller engine bay thatn a F/S truck.

Good luck with the swap, and keep us posted!

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Ok, I did some more looking around and I think my transmission is a 30RH. I haven’t seen any one adapting this to the 5.9L. Could it be as easy as changing the bell housing or would I have to get another transmission? My goal is to re-use the transmission I already have.

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If you are referring to the transmission in the '98 XJ, it is an AW4.

 

Willy

 

only if its a 4L

 

Also, to the OP, FYI if you use the ZJ or DR computer it will have the CCD bus so all your factory guages and overhead console can be made to work seamlessly.

 

 

There is a 5.9 ZJ down at a junkyard near me, If I wanted to do the 5.9 swap it was complete with everything there.

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I was planning on running the megasquirt for the fuel only. Do you think my gauges will go crazy and lights on the dash come on if I leave the factory computer in just disconnect the fuel management part? I haven’t seen any xj with 360 in them. Well ive only seen a picture of a blue xj with a 318 sitting in it. Odds are they just swapped every thing over, engine, tranny, harness, ext.

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I was planning on running the megasquirt for the fuel only. Do you think my gauges will go crazy and lights on the dash come on if I leave the factory computer in just disconnect the fuel management part? I haven’t seen any xj with 360 in them. Well ive only seen a picture of a blue xj with a 318 sitting in it. Odds are they just swapped every thing over, engine, tranny, harness, ext.

 

IMO it will be way easier to just let the Chrysler ECU run everything, that way all your gauges and overhead console will work right.

 

Why spend more time and money to make a megasquirt work, when the OEM stuff is already setup and just needs some wires connected.

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I'd like to go back to the original post for a moment or three:

 

I was going to stroke my 4.0l but my overhead display wouldn’t be correct any more.

 

WHY would stroking your 4.0L engine in any way deactivate your overhead console display?

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It doesn’t deactivate it; it can’t calculate it correctly with larger injectors. It will be off a cretin percentage, I guess I could do a math equation every time I look at it!! but that’s no fun! :smart:

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It doesn’t deactivate it; it can’t calculate it correctly with larger injectors. It will be off a cretin percentage, I guess I could do a math equation every time I look at it!! but that’s no fun! :smart:

 

Thats only if you went with larger injectors.

 

Of course, if you use a megasquirt you won't have any overhead functions either, so its a toss up.

 

The better option is really the newer 4.7.

 

I saw a rolled 2004 WJ overland with the high output 4.7(which is a better engine than the 5.9, and makes more power/torque) sell for $1700 yesterday.

 

You could sell the NAV out of it for $350, the leather seats for $200, airbags for $300, rear end $???? front end $?????.

 

That puts you at less than $1000 for the whole swap in parts costs.

 

Then if you used a 02+ TJ Guage cluster(which bolts in the same as the XJ gauge cluster), you would retain all your factory guages. And then if you used the WJ overhead console you would keep all the mileage functions.

 

Plus you would have a complete engine/trans/wiring harness/computer to take with it all, and not be scrounging for parts.

 

All the ancillary things like PS hoses, AC, etc would still require the same amount of fab as with the 360.

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If you are referring to the transmission in the '98 XJ, it is an AW4.

 

Willy

 

only if its a 4L

 

See his original post.

 

I have a 98 xj classic 4.0L auto. I can't remember what the transmission is I think it’s a 42r-something.

 

Willy

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If you are referring to the transmission in the '98 XJ, it is an AW4.

 

Willy

 

only if its a 4L

 

See his original post.

 

I have a 98 xj classic 4.0L auto. I can't remember what the transmission is I think it’s a 42r-something.

 

Willy

 

Yup and gawd help some poor soul if they read that as all 98's have the AW4.

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Are you certain that larger injectors will mess up the overhead display? I assume you mean the MPG function. How is that calculated, and why would larger injectors make it less accurate than it already is?

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