I was thinking of doing same thing, I am a mechanic so thought I had some advantages. All I hear from peeps is its not worth it, go buy a YJ w/ the 4.0L. Thought I would buy a cherokee doner that way I have anything I would need. brackets, harness's, exhaust parts, etc XJ's are cheap in my area and very populated at the junkyards. wranglers not so much
What year is your 2.5L? 1987-1990 you have to swap the whole harness, 1991-1995 you can use the existing harness, just have to wire up the new injectors.
Would you rather swap in an engine or buy a Jeep with the 4.0 already in place?
Even so, you have to get bigger tires for the 4.10 gears. Manuals are 3.07 and autos are 3.55 I believe, for the 4.0, whereas the 4 cyl got 4.10's. Otherwise you'll be over-revving your 6 cyl. You are obviously going to need to swap in the AX15 and matching NP231J. And the computer, as well as weld on new mounts and whatnot.
Not really reviving a dead thread since it is only a week old but I need some clarification on this.
I have a '93 with a 2.5 and a manual transmission. After driving it for the first time a few weeks ago I was really disappointed on the highway. I need an engine that can handle driving at 75 as well as offroad. The 2.5 cannot. You guys are saying the same year Wrangler with a 4.0 is a different beast? I was hoping I could simply drop in a 4.0 but you are saying I would have to replace the transmission and rework the gears as well?
If it requires that much work would I just be better off selling it and buying one with a 4.0?
It is stock. I can hold 75, with my foot nearly buried. Any hills and the speed slips. Keep in mind that this is in Colorado with thin air. I burned 3/4's of a tank of gas between Denver and Colorado Springs trying to maintain 75-80 when returning from DIA.
It does fine in town, but I-25's speeds are a struggle.
auto trans 6 cylinders are 3.07 gears. cherokee with 4.0 and auto are usually 3.55-3.73 gears.
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These are the factory standards for the YJ:
2.5L manual - 4.10
2.5L auto - 3.73
4.0L manual - 3.55
4.0L auto - 3.07
3.07 - used with 4.0L engine / manual transmission
3.31 - only available on older (pre87?) 2 door XJs with "Fuel Economy" package
3.55 - used with 4.0L engine / automatic transmission
3.73 - found in some XJs with the towing package
4.10 - used with 2.5L engine usually, and older XJs with the "Off-Highway Vehicle" package.