OK, so let's be serious...4.7l swap.

Discussion in 'KJ General Discussion' started by JeepCoMJ, Mar 14, 2013.

  1. JeepCoMJ

    JeepCoMJ Full Access Member

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    I know I recently pm'd someone that I had no interest in doing a 4.7 swap after they suggested it.

    That said...I'm considering it.


    After going through some considerable research, I've decided several things;

    1. for similar years, both the 3.7 and the 4.7 have the same block casting to the farthest forward hole, tho the 4.7 obviously extens one more cylinder

    2. The 4.7 is really only about 4 to 5" longer than the 3.7

    3. The intake for the 4.7 would pretty much fall into the same location

    4. If you use the 3.7 harmonic balancer, a/c pump, and alternator, which all bolt up, then you will be able to use the OEM serpentine to your vehicle, eliminating hassle when ordering parts

    5. While the flange on the exhaust manifold may be different for the forward cats, it would not be hard to rectify that problem

    6. Everyone is overthinking this swap.



    Here's the basic deal. A 4.7 will bolt up to the 45RFE trans that are in all of my 02 KJ's. Likewise, based off of my measurements, the 3.7 motor mounts will bolt directly to the 4.7 block.

    Assuming there are no real issues with the oil pan and clearance (which it is more likely that there will not be, as they were designed off the same piece), the motor should actually bolt right in.

    If you do not run a mechanical fan, there is actually enough clearance in the engine bay to put the non-mechanical fan shroud with e-fan in, and add a pusher fan from a CRD

    That said, the KJ's radiator might not be enough to cool the 4.7. I'm sure that there are several aftermarket full aluminum radiators available that could remedy that problem.

    The intake manifold places the throttle body in darn near the same location as the 3.7, if not exactly, if you are using similar year. Likewise with the fuel rail and where you hook it up. A longer hose might be necessary, but no big deal.

    As far as wiring and sensor issues etc...

    If the donor motor has the proper tone ring and cam ring (whatever you call it), with the matched similar year ECU, modifying the existing harness to be compatible with the v8 harness (or vice-versa) would be pretty darn simple.

    The only real problem that I see is whether the tachometer will read properly...which it should based off of the information I'm finding about tachometer signal.




    This whole deal is really pretty straight forward in my opinion.

    I guess the next thing I'm going to need is a 99-02 4.7 longblock, intake manifold, fuel rail, flex plate, and exhaust manifolds. I really don't even need a good motor, but I'd like to mock this up and put it in my liberty to show just how possible it actually is.
     
  2. dude1116

    dude1116 Full Access Member

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    It's actually been done. There's a thread around here somewhere. In either case, I commend your mechanical expertise!
     
  3. JeepCoMJ

    JeepCoMJ Full Access Member

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    I cannot find a thread on it anywhere
     
  4. dude1116

    dude1116 Full Access Member

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  5. tjkj2002

    tjkj2002 Full Access Member

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  6. dude1116

    dude1116 Full Access Member

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    I found that odd too. But hey, pics and vids are pics and vids!
     
  7. JeepCoMJ

    JeepCoMJ Full Access Member

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    Well that confirms it for me. I'm looking for a complete junk motor for mockup now.
     
  8. jeeptorino68

    jeeptorino68 Full Access Member

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    from some pictures i have seen you are right about the intake/TB. i saw pictures where they had the 3.7 powertech air box silencer on the 4.7 throttle body possibly in the thread above.
    i really want to do this if our 3.7 ever dies.
     
  9. TwoBobsKJ

    TwoBobsKJ Full Access Member

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    I've wondered about this especially after just swapping in a new 3.7....

    Are the additional cylinders of the 4.7 on the front of the block? If so I'd think the motor mounts would be on the same location on the 4.7 block as the 3.7 - it doesn't seem logical that the bosses for the mount would be cast in a new location for the 3.7.

    To me the one issue that may pose a problem is the location of the cats coming off the exhaust manifolds - will the clear the firewall, bolt up to the crossover pipe and allow enough clearance around the transmission pan...?

    The wiring harness from a 4.7 donor vehicle should take care of the additional coil packs and injectors - and the cam ring and crank reluctor ring kit that's available would ensure the timing is correct for the '02 computer. If I were motivated to do this project I'd look for a 4.7 as new as about 2011 or so with low miles and have a go of it.

    Keep us posted.

    Bob
     
  10. tjkj2002

    tjkj2002 Full Access Member

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    That new of a 4.7 may be alot more tricky since it has 16 spark plugs,room will be a factor to access those bottom 8 plugs.
     
  11. 04Liberty

    04Liberty Full Access Member

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    The other obstacle there is up through 05 KJ's are PCI bus vehicles and any 4.7 newer than 2006 will be CANbus based. I don't know if you could get the 2 different systems to talk to each other properly. If I were gearing up for this, I'd try to find a 2005 Ram based computer setup. Excellent custom tunability and still a PCI bus system.
     
  12. JeepCoMJ

    JeepCoMJ Full Access Member

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    still over-thinkin.

    what the motor came out of doesn't really mean squat.

    The tone ring and cam timing ring can be swapped to match your year computer.

    What the sensors came out of and whether they are compatible with the motor you have, DOES.

    Since the blocks didn't change, and intakes seem to be consistant, I'd just as soon get a good one out of anything, and make it work.
     
  13. tjkj2002

    tjkj2002 Full Access Member

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    Actually alot changed with the GENII 4.7's and will not work with GENI computers,CAN Bus or not.
     
  14. JeepCoMJ

    JeepCoMJ Full Access Member

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    :happy107:
    Most of the parts can be swapped, and tone rings etc. can be swapped or custom machined and swapped.




    Either way, picking up an 01 4.7 out of a durango, and 02 ECM out of a WJ. Will be using 3.7 sensors, except crank and cam unless I find that they will work.

    Will be repinning and adding to the factory 3.7 harness to make this work.
     
  15. jeeptorino68

    jeeptorino68 Full Access Member

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    lots of pictures please
     
  16. JeepCoMJ

    JeepCoMJ Full Access Member

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    There will be, at some point, but not until I am finished and it's driving. This is one that I want to do a build thread that you can read start to finish on the first page. Don't need a bagillion comments making it harder to absorb the tech involved.
     
  17. JLRockies

    JLRockies Full Access Member

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    Ok, looking forward to someone raising this thread from the dead in a year or so.
     
  18. JeepCoMJ

    JeepCoMJ Full Access Member

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    You'll see it all done in about 3 weeks. I'll post pics with the engine installed by the end of the week.

    I'm getting the mechanical aspect done before I consider wiring...want to get as many parts installed as possible.
     
  19. TheBlueKJ

    TheBlueKJ Full Access Member

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    (popcorn)

    Can't wait to see the finished product
     
  20. wheeee32

    wheeee32 Full Access Member

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