Replacing my 2.5L with a 4.0L

KCsTJ

KCsTJ

TJ student
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Jan 9, 2018
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Farmersville, TX, United States
I would like to replace my 97 2.5L engine with a 4.0L.

I want to replace the 2.5L engine only. i want to keep the 32rh 3 speed tranny cuz it has just been rebuilt.

Before i start doing the research, has anyone here done this with success?

I can do the labor, the thing that concerns me is, will the 4.0 PCM match with my 32rh 3 speed automatic?

The last thing i want are PCM issues.

Am i limited to finding a used 4.0L from a 32rh or can i buy a new crate 4.0L and specify a 32rh 3 speed tranny compatable PCM?

Will the 32rh 3 speed stand up to the 4.0L power and a few wheeling adventures each year?
 
I also have the 2.5L. Can I ask why you are looking to change this? What do you use this jeep for? What is your tire size or plan for tire size? You may may be happy with just changing your gear ratio. There are many options of swaps out there, and searching in the forum will find you almost all of them. That being said, the 4.0 is almost a worthless swap in my opinion. Look up gear ratio as well on a simple search.
 
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TimboSlice said:
I also have the 2.5L. Can I ask why you are looking to change this? What do you use this jeep for? You may may be happy with just changing your gear ratio. There are many options of swaps out there, and searching in the forum will find you almost all of them. That being said, the 4.0 is almost a worthless swap in my opinion. Look up gear ratio as well on a simple search.
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Yes, well i bought a 4.0 Sport two months ago and love the power. The 2.5 runs fine and has 169k.
i would like to to beef up the 97 and keep the 05 mostly stock.
Short answer, i just like the power. :)
 
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KCsTJ said:
Yes, well i bought a 4.0 Sport two months ago and love the power. The 2.5 runs fine and has 169k.
i would like to to beef up the 97 and keep the 05 mostly stock.
Short answer, i just like the power. :)
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Hemi swap!!!!! More power. Lol. Seriously though , numerous threads on the subject suggest the work is the same. I might find a donor Grand Cherokee with a v8 and auto and start from there... But I have a 4.0 ;)

Sent from my Pixel using Tapatalk
 
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Same amount of work to do a GM LS engine swap or many other options, if power is what you are looking for.
 
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Personally it's easier to just sell the Wrangler and buy one with a 4.0 already in it. I'm sure most will agree on that.
 
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Also, your 2.5 doesn't have a 32RH, it has a 30RH.

You'd have to swap in the 32RH as well, as the 30RH isn't strong enough to hold up to the 4.0 long term.

Those transmissions aren't controlled by the PCM, as they are hydraulically controlled. So your PCM would likely be fine.
 
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Chris said:
Also, your 2.5 doesn't have a 32RH, it has a 30RH.

You'd have to swap in the 32RH as well, as the 30RH isn't strong enough to hold up to the 4.0 long term.

Those transmissions aren't controlled by the PCM, as they are hydraulically controlled. So your PCM would likely be fine.
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Yes thank you @Chris, it has a 30rh.
Sorry for my confusion!

Ok thats what i was concerned about, would it hold up over time.
I think ill keep the 2.5L and use it for a cool looking around town jeep . :)
 
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KCsTJ said:
Thank you @Billwynburger , i was looking for a thread like that!
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You're very welcome, nothing wrong with wanting more power. If my jeep was my daily driver I think I would look into more myself but at my age and condition which is half blind, a bad back and I can't hardly hear myself fart, so now I join the herd of turtles in the right lane.
 
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Billwynburger said:
You're very welcome, nothing wrong with wanting more power. If my jeep was my daily driver I think I would look into more myself but at my age and condition which is half blind, a bad back and I can't hardly hear myself fart, so now I join the herd of turtles in the right lane.
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@Billwynburger you sound like the perfect jeep head :) you are doing just fine
 
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KCsTJ said:
Yes, well i bought a 4.0 Sport two months ago and love the power. The 2.5 runs fine and has 169k.
i would like to to beef up the 97 and keep the 05 mostly stock.
Short answer, i just like the power. :)
Click to expand...
Of course the 4.0 has more power and is a good motor. I would consider installing the stroker motor. 4.0 head with 4.2 crank. Search them on google nice replacement fits in like the 4.0
 
KCsTJ said:
@Billwynburger you sound like the perfect jeep head :) you are doing just fine
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Of course even with the 4 banger I still plan on a lift kit & larger tires along with a re-gear but again it's not my daily driver. Here's a photo I found which is how I hope to see my jeep once it's finished. The perfect amount of lift, not too much empty, unnecessary fender space, just the right amount.

2inchlift.jpg
 
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Actually the 5.9 from a GC is as easy as the 4.0 swap.... All Mopar...
KCsTJ said:
Yes but i dont want to go overboard, as much as i would love an LS swap, just too many details.
Thats why i want to stay with a 4.0, nothing too tricky, i hope. :)
Click to expand...

Sent from my Pixel using Tapatalk
 
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Jerry Little said:
Of course the 4.0 has more power and is a good motor. I would consider installing the stroker motor. 4.0 head with 4.2 crank. Search them on google nice replacement fits in like the 4.0
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Yes indeed, @Jerry Little dont get me going on a stroker motor i would absolutely love to have one, now that is tempting...thats bringing out the hot rodder in me ... :)
 
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fxrsliberty said:
Actually the 5.9 from a GC is as easy as the 4.0 swap.... All Mopar...

Sent from my Pixel using Tapatalk
Click to expand...

A local guy in town has a 5.9 in his LJ Rubicon. He let me drive it for a while as I was considering buy it.

I was less than impressed with that 5.9. It didn't have loads of power or anything. Sure, it was quicker than my 4.0, but it wasn't enough power to make you do a double take.

My previous 4.0 with a supercharger had just as much power as that 5.9, I can say that with certainty.
 
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