Hemi swap

Engine Swaps

  1. MotorHoggGears

    MotorHoggGears Well-Known Member

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    So im thinking about swap a 5.7 hemi engine and transmission into my 1980 Chrysler Lebaron. I have found the kit for it drop in but worried about the driveshaft and the differential. It 8.25 open differential that's connected to a slant and confused on the computer. I'm making this build for a daily driver and to compete against classic cars with modern day engines.???
     
  2. Duke5A

    Duke5A Well-Known Member

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    Schumacher Creative Services has a lot of swap parts if you still need anything.

    As for survivability of the axle, a stock 5.7L Hemi is rated for around 380 HP. You can hit that with a mild 360 build and plenty of guys have run them in front of 8.25" axles. I would only worry about it if you had plans of converting the car to a manual transmission. Tires also play into though. What kind of traction are you planning on? Is the car going to see track time?

    The factory u-joints on the car are the tiny ones (7260). That being said though I ran them for a decade with an aluminum headed 360 and even for a year behind my 512 stroked big block (not recommended though).

    The ticket used to be finding a Mopar 8.75" rear from a 66-70 B body car. They slip right in, but finding them now is the hard part.

    In short, yes it'll work and survive, but it won't leave much room for upgrade. If it were me I would be looking brand-X axles from something newer with disc brakes. A couple guys here have done Ford 8.8 swaps. They're cheap and wrecking yards are full of them. Even Ford 9" axles.

    If you have any questions regarding the electronics you may want to head over to the GenIII forum on Moparts. To my knowledge nobody here has undertaken a GenIII swap yet.
     
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  3. MotorHoggGears

    MotorHoggGears Well-Known Member

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    Thank you for all the info!!
    No I'm using the motor and auto transmission from a 08 dodge charger and I thought I might have to ✂ the driveshaft and change the rear end to lay power down to the floor. As far a tires haven't got that far but looking a pair of 20 inch dodge charger wheels with that black carbon look.

    Its not that 8.75 is so hard to find its more ppl want to much for some of these parts.

    Ob2 connection with a pedal commander o open up that throttle for faster response , cold air intake k&n high flow filter?

    I'm also in the process to try to get a newer interior I want the 2012 or newer chrysler 300 interior , because I want some accessories for modern days. Like the cluster, dash, steering wheel ,seats, and carpet. I know fabrication will be needed but its well worth it to have a classic car with modern day technology!!
     
  4. Duke5A

    Duke5A Well-Known Member

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    There is a lot that goes into the electronics. You won't just need the ECU. Unless it sees everything, including the body control module I don't think a factory computer will even run. You need to talk to someone who has done this swap before. As far as I know there are no aftermarket standalone computers to run the transmission either. This is why guys who do this will run either a 518 or 727 with a GenIII motor because there is no way to make the new eight speed work.

    One thing I can give an opinion on though is the rims. I have 18" wheels on mine with 285-40-18 tires on the back and 245-40-18 on the front. It's going to ride harsh, and I do mean harsh! These old school suspensions just aren't made to ride nice with no sidewall on the tire. I'm giving some serious thought to stepping back to down to 16" rims. I've already bent two rims in the last three years.
     
  5. Aspen500

    Aspen500 Well-Known Member

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    The electronics will be the tough part. To run everything, the car needs multiple modules and they all have to communicate and get the correct data. That incudes PCM, instrument custer, bcm, tipm, ignition nde, tcm, on and on. They all need to be from the same car and get all the inputs same as the donor car, otherwise, as Duke said, the car won't even crank nuchles start and run. Goes for the trans, guages, even the radio (if from the Charger). Multiple communication networks, multiplexed sensors,,,,,,,,,,,,,,,,,,,,,it's hard enough getting it all to work on a stock modern vehicle. Heck, some won't even crank or start if the ABS module isn't plugged in or has an open internal circuit.

    Not trying to discourage you though!:D
     
  6. MotorHoggGears

    MotorHoggGears Well-Known Member

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    Lol I understand but yea I was going to take ecm, fusebox and wiring harness for all to work from a chrysler 300 and the transmission is a 5 speed auto and I like advice helps me and others that have thought about it.. But about the fuel system that where I'm lost as far the gas tank and fuel pump????
     
  7. Aspen500

    Aspen500 Well-Known Member

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    If you decide to use only the engine and trans (not cluster or other parts), you can get stand alone ECU's and wire harnesses. It's when other module controlled parts are used that it becomes very complicated. Every make is different but, some use the ABS for speed signals or other inputs and without the ABS, none of it will work (just an example). In some cases, the fuel pump is controlled by a module, which gets inputs from the ECM (and possibly ABS, BCM, etc) then controls the pulse width of the pump, which sends data back to the ECM...........................Well, you get the picture.

    I am by no means an expert on retrofitting new to old, just know how integrated everything is on newer cars (I'm an auto tech). Example: Recently we had a 2016 Chevy Traverse in the shop that wouldn't crank, the cluster was dead, the power windows didn't work, among a few other things. Problem ended up being a shorted (due to salt water intrusion) side obstacle detection sensor/module in behind the right side of the rear bumper. Took the whole network down so everything on that network also went down and some things on another network were disabled due to missing inputs from modules on the network that was down. I love my job, I love my job, I love my job, lol.

    There is a member with a late Hemi Mirada (or Cordoba?) on here. Apologies to him and you, I can't for the life of me remember his screen name at the moment.
     
    Last edited: Feb 4, 2020
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  8. MotorHoggGears

    MotorHoggGears Well-Known Member

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    Thank you but I think wiring I PE
    Pretty confident in
     
  9. Aspen500

    Aspen500 Well-Known Member

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    Remembered it. Screen name is Joe12459 and he did a swap, including the electrical system, interior, dash, among other things. He would probably big a big source of info. I believe he used a Charger donor.

    There are threads with photo's somewhere on this site. May have to do a search but, they're here.:)
     
    Last edited: Feb 4, 2020
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  10. MotorHoggGears

    MotorHoggGears Well-Known Member

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    Lol hard find when did this happen
     
  11. Aspen500

    Aspen500 Well-Known Member

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    Here's one that has a bunch about it. If you click on the "search" box (far upper right side of screen) and type in Joe12459 where it says "Posted by Member" it'll bring up a list of his posts and then you can scroll through and find ones on the Hemi Mirada he built.

    gen 3 hemi swap in a j body?
     
  12. Joe12459

    Joe12459 Well-Known Member

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    I built mine in 2015. I posted pics and info here somewhere. I used Hotwire harness to control engine and NAG1 trans. You need factory PCM, TCM, BCM, ABS module and accelerator pedal. The harness kit comes with a tone ring that attaches to the driveshaft flange, to provide signal to the computers. i had my driveshaft made by The Driveshaft Shop, but I've seen many places that make them. I used a 68 RR 8 3/4 rear. I used an RMS AlterKtion front end, and I welded in the motor mounts several inches forward of where a stock small block would be, which allowed me to use that trans without cutting the floor/tunnel at all. If you use stock k-frame with conversion mounts, you will have to modify the floor and tunnel.
     
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  13. Joe12459

    Joe12459 Well-Known Member

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    OH, I forgot, you need the shifter, too.
     
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  14. MotorHoggGears

    MotorHoggGears Well-Known Member

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    Did you have any issues with steering? Did you switch to rack and pinion setup? I'm using a 05 hemi ram ecm wiring harness cause it's more plug and play setup this way for the motor and transmission not to much to worry about but I'm lost when it comes to the shift linkage and stuff?
     
  15. Joe12459

    Joe12459 Well-Known Member

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    I used the RMS AlterKtion front suspension, which is rack and pinion. How will you control the NAG1 trans with the Ram harness? I believe the Ram had the 545RFE. The 08 Charger is NAG1. It will need an external speed signal to the PCM and TCM to shift.