1. #1
    stepheng67's Avatar
    stepheng67 is offline Junior Member
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    Question Can I replace a 4 cylinder engine with a 6 cylinder

    I am in the market for a jeep YJ or TJ years 1993-1999. I have found many with 4 cylinder high mileage engines. I am not opposed to finding a 6 cylinder, but I don't mind buying and changing the engine out if it is possible without much trouble? How much trouble is it to replace the 4 cylinder engine with the 4.0 6 cylinder? Are the engine mounts the same? Bell housing? Transmission? What other issues would I need to be aware of? I have not owned a jeep since the early 80s when I had an underpowered 4 cylinder CJ 5.

  2. #2
    Bounty__Hunter's Avatar
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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    Nothing easy about it. Tranny won't work, motor mount perches need cut off and rebuilt, new wiring, etc. Since you're in the market, hold out for a 4.0L.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    Thanks for the answer, that was kind of what I have been leaning towards. I just needed someone with more knowledge to keep me from making a bad decision. Do the fuel injected fours have enough power to run the YJ and TJ? I just remember my 4 cylinder CJ-5 barely getting the speed limit with a 20 mph tail wind.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    The FI 2.5L has come a long way, '91+ has a lot more power, but it's personal preference on if it's enough power for you. I like mine, even after owning a v8 YJ. Most of the driveability is in the gearing, mine runs 5.38 axle gears to turn the 35" and 36" tires.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    better choice; put a 318 in it. or maybe a 3.9 out of a Dakota; they used the same AX 15 trannys (other than bellhousing) teh same 231 t case etc and being also a Mopar product a similar year swap oughtta be plug n play.

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    Bounty__Hunter's Avatar
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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    A v8 or v6 will not be plug and play. Still need to address cooling, motor mounts, and a custom wiring harness.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    Well, if you are considering the engine swap, then I'd say a V6 or V8 is a better option than the I6 (it will make it more worth your time and effort, anyway). I do agree with Bounty, though, in that the 4 banger is not that bad. Mine runs on 31's and I run 4.88 gears, and I can hold steady at 75 mph even in headwinds (I can even accellarate in 5th at 60mph, or hold 65 mph going uphill - which in Miami means overpasses). but if what you really want is the I6, better to buy that directly.

    '94 YJ 2.5L, Sperwinch EPi 9.0, RE 4" Std Lift, Adv. Ad. SYE, Woody Shafts, Alloy Axles, ARB Lockers, 4.88 gears, 62mm TB & Spacer, 165A Alternator, Griffin 3" Aluminum Rad, Taurus e-fan w/ DC Controller, Borla Cat-Back, Flowmaster hiflow cat, PD Ignition, 19# injectors, Adj. FPR (42PSI), MOPAR cam, Safari Snorkel, 33" BFG KM2, 15" AR wheels, Xenon H4 lights, KC Daylighters & Slimlites, Sony sound, Pavement Ends Targa Top, Hanson Front Bumper, JCR Offroad rear, AtoZ Rockers, Rhino lined Tub.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    I agree with Bounty Hunter, you are better off buying what you want in the first place than getting something else and trying to turn it into what you want. Buying a jeep with a 4.0 already in it will also be cheaper in the long run.

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    Re: Can I replace a 4 cylinder engine with a 6 cylinder

    There are things you can do to an engine short of replacing it. Sometimes just regular maintenance is all you need. Have a compression test done on the cylinders. If bad rings are causing a compression loss, a ring job is alot less expensive than an engine swap, and give you the power you need.

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