What is involved in replacing a 5.2 with a 5.9

Small Block Mopar Engine

  1. SGBARRACUDA

    SGBARRACUDA ROY FABO Gold Member

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    I bought a few trucks recently and one is a 2000 1500 2WD with a knocking 5.2 Automatic.
    A friend of mine has a new 5.9 long block still wrapped up in plastic. So my question is, what needs to be done to make it work where a 5.2 was? Mainly with the electronics. Thanks for your help.
     
  2. MOPAROFFICIAL

    MOPAROFFICIAL Well-Known Member

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    Maybe the computer from a 5.9, flex plate/external balance convertor, damper, check on throttle body..but a few searches could clear up if any induction difference.
     
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    • 67Dart273

      67Dart273 Well-Known Member

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      I bet you could do nothing except change the flex plate and it would fit and run just fine. "Might be" that the TB is larger bore, don't know for sure, and computer/ injectors different.
       
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      • pishta

        pishta I know I'm right....

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        Balance...TB and injectors are the same (part numbers)....Maybe ECU?
         
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        • SGBARRACUDA

          SGBARRACUDA ROY FABO Gold Member

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          Thanks, I'm trying to decide weather I should find a 5.2 or if the 5.9 would be doable without to many headaches.
           
        • 67Dart273

          67Dart273 Well-Known Member

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          ^^This is the big difference in the older LA and the Magnums, too bad the LA's weren't done this way. Magnums are balanced with weights on the flex plate, while LA was balanced with weights on the converter. Magnum converter bolt pattern is not indexed, either.
           
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          • SGBARRACUDA

            SGBARRACUDA ROY FABO Gold Member

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            So I guess with the right 5.9 flex plate the original 5.2 converter will work?
             
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            • Jadaharabi

              Jadaharabi FABO Gold Member FABO Gold Member

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              .
              The balance is not the same between a 5.2 and a 5.9.
              You need a 5.9 flex plate. I believe everything else swaps over.
               
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              • Jadaharabi

                Jadaharabi FABO Gold Member FABO Gold Member

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                Also Chrysler changed the rear main cap to where a 5.9 oil pan fits on the 5.2. So no problem with the oil pan.
                 
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                • MOPAROFFICIAL

                  MOPAROFFICIAL Well-Known Member

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                  Balancer/dampner is diff, internal vs external.
                  I get different part numbers on the magnum balancer between 5.2 and 5.9. Mine looks nothing like a neutral balancer from a 5.2
                   
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                  • Bobzilla

                    Bobzilla Well-Known Member

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                    Converter should be the same, just need proper 5.9 Magnum flex plate and 5.9 Magnum harmonic balancer. There is two styles; a one piece with integral serpentine pulley, and the two piece that is separate balancer and serpentine pulley. Either setup will work on the same 5.9 Magnum long block, if it doesn't already have one.
                    Everything on the intake manifold works on either engine, so just make sure the plenum plate is sealed up and swap it over.
                    The ECM from either engine will run the other engine size as long as they were equipped the same, meaning same transmission style. I have plugged several different ECMs, both 5.2 and 5.9, into my trucks and they will run and drive normal. The only thing nobody can guarantee, unless they tried it, is if you can run that 5.2 ECM on a larger 5.9 engine while towing under heavy load. The camshafts have only very little difference.
                    The factory ECM tunes were very soft, so I think it would be safe enough, but getting another ECM is cheap and easy. Lots of these trucks in salvage yards. I usually only have to pay $45 bucks for a used ECM, in my area.
                     
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                    • krazykuda

                      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                      THe passenger side motor mount is the same for all small blocks, but the driver's side is different widths between the 273/318 and the 340/360, so you will need to get the proper left side motor mount....
                       
                    • Max1196

                      Max1196 Well-Known Member

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                      He's working with a "Magnum" 2000 vintage, the early style mount business should not be applicable for his truck.
                       
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                      • pishta

                        pishta I know I'm right....

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                        Yes, my answer was balance too. Then added the TB and injectors were the same. Maybe didnt come out looking like that but it looks like a viable swap with the right flexplate. I wonder if the 5.2 ECU would figure the added duty cycle of the 5.9 when it saw a lean condition from the o2 sensor? Some ECU's are pretty nailed down while others (EECIV) are dynamic, and learn the motors profile.
                         
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                        • SGBARRACUDA

                          SGBARRACUDA ROY FABO Gold Member

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                          I am also buying a truck 5.9 (not sure on the year yet) complete engine with pullies, accessories. mounts.comp, alt, everything. Just don't know the history of it. So I should have everything I may need. Just waiting to get the tittle on it before I buy the two engines. Truck is club cab and is real nice. I also got a 2002 Dakota 4x4 quad cab 4.7 auto that is in nice shape. The other one I will get eventually is a 1996 ext cab Dakota. Bad 3.9.
                           
                        • dusted

                          dusted FABO Gold Member FABO Gold Member

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                          Ecu is the same, program is different but it will run just fine with the 318 computer. We’ve done it before.
                           
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                          • 67Dart273

                            67Dart273 Well-Known Member

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                            Just a stray "becuz" and I know you have an automatic.......The "White Whale III" an 01 Dodge 2500/ 5.9 gas, auto, I was considering swapping to a 5 speed.......and the crank IS NOT DRILLED AT ALL for a stick pilot!!! Only the converter bore is bored
                             
                          • RustyRatRod

                            RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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                            @Bighead440 didn't you determine the 360 can run off the 318 electronics? I know somebody I know did.......I thought it was you.
                             
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                            • Bighead440

                              Bighead440 Well-Known Member

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                              My 1992 D-150 that you found for me in Perry had a blown 5.2 and I replaced the long block with a 5.9, mildly modded even. I just "fooled" the ECM by using higher flow injectors (slightly, like 19.5#hr stock to 22#hr 4-hole units from Five-O Injectors). The cam is 200/206*@.050",112LSA and I used a single plane 2bbl M1 intake and shorty headers. Very peppy with zero driveability issues, sounds better, but drives like bone stock. Gets 15mpg hwy, typical 360-LOL.
                               
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                              • MileHighDart

                                MileHighDart Well-Known Member

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                                Just add .7
                                 
                              • RustyRatRod

                                RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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                                The Viper Truck. LOL
                                 
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                                • Bighead440

                                  Bighead440 Well-Known Member

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                                  viperTruck.jpg
                                   
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                                  • dartfreak75

                                    dartfreak75 Restore it, Dont part it! FABO Gold Member

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                                    Thanks for sharing this thread with me roy!
                                    I'm gonna reopen it lol I have a couple questions
                                    1) the swap I'm considering is a 5.2 to a 5.9 as well but my 5.2 is a 5 speed manual the 5.9 is an automatic I am keeping the 5 speed what do I need as far as flywheel goes for the 5.9 to keep the balance ? Will the 5.2 flywheel mess with the balance or does it have to be a 5.9
                                    2) i know the tb and intake are the same but electric wise will the computer have to be changed i have both computers so changing it wont be that big of a deal but if I dont have to I wont!
                                    3) are there any difference in the injectors or are they the same too? I'm thinking about since its gonna be out anyway going ahead and getting the huges tb mod and replacing the plenum gasket I'm sure it needs it. I may even pull the heads and clean the valves and everything really good I'm not sure yet. I'd like to do headers also. What modifications can I make to the engine without messing with the computer at what point will it need to be reprogrammed or whatever has to be done? I'm not real knowledgeable with newer computer controlled engines so this is new to me. Thanks
                                     
                                  • 67Dart273

                                    67Dart273 Well-Known Member

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                                    You will have to get a 5.9 flywheel for balance. Also THE ENGINE MAY NOT BE DRILLED at all for a pilot if it's out of an auto. One of mine was not. This is not as hard as it sounds. You can drill an "oversize" hole "by hand" to clear the pilot, measure carefully and make it deep enough to clear the pilot as well as large enough. Then use one of the large fat pilot bushing/ bearings that fits the big converter bore.
                                     
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                                    • Bighead440

                                      Bighead440 Well-Known Member

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                                      I did a '92 D-150 swap from 5.2>5.9L and all I did was use fatter injectors recommended by Five-0-Motorsports to supply my mildly modded (200/206*112LSA cam) '97 360 Magnum. The 5.2L PCM works fine!! 5.9mag2.jpg
                                       
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