Thanks for letting me in. Been reading many forums and discussions about the low-end Magnums, such as mine - 2.7L v-6 - and I want to see if I have a handle on things.

Keeping to essential overall generalizations here, basically, the platform for the 2.7 and the 3.5 are the same coming down the assembly line; i.e., split at the junction for engines, and it goes left for the 2.7, center for the 3.5, but the Hemi-cars are on a different line, because of the underlying k-members, is that close?

The Body/Frame assembly does not care about the powerplant [of these two], they are interchangeable. Or are they?

That said, the Electrical seems to be where it all goes south, as the harness for the 2.7 is significantly different from the harness for the 3.5, is this right? Different engine control chips, senders/receivers are not the same, even for similar purposes like throttle bodies, temp, oil, the usual monitors.

And the transmissions between the 2.7 and the 3.5 require different computers chips, as well?

Does it stop at the firewall? In other words, is the harness alike for everything else from the firewall back, but different under the hood, or is the entire wiring affected?

If I want the 3.5, and I take the engine/trans and underhood harness together from a donor, will it transplant clean, plug in to the firewall junction, and all the necessary elements work?

I have owned the car for a couple of years, put money into the front end, rear fuel system [including tank, pump and related gear], but it was not well-cared for by the previous owner - even the electronic key is non-functional, as the internal battery connections were all broken, it holds no battery or juice - so now I am at that point where the engine needs the attention, preferably the easiest course.

The usual 'junk it and buy the Hemi' calls are not appropriate here, this is what I have to work with, but I do have some flexibility, if the 3.5 swap can be relatively painless, or even just rebuilding the 2.7.


On the other hand, more fantasy than serious plan, but jerking the harness and re-wiring/re-building for a small block motor-and-trans, like a 340, just for the helluvit, appeals to my Roadworthy/Roadkill side, lol.


Thanks, I appreciate the discussion.

 

So really, this is your question. And a quick google for "Dodge 2.7 to 3.5 swap" comes up with many forum posts, YouTube videos and the like.

But, TLDR, yes. All you need is the engine harness. BUT, there are many changes and differences between years and trims so be sure to get the right one for your engine!

https://www.chargerforums.com/thread...1#post-4644073

 

And here is a list from another member who did the swap.

 

Indeed, a quick search reveals lots of swap info, and videos of folks doing many swaps - but as you note "...there are many changes and differences between years and trims...", and this is a part of what I was asking about, because the manuals I have are necessarily incomplete [I have not yet sprung for the Factory books], and questions about the k-members, wiring, and most especially the computer chips, have remained unanswered or vague.
I appreciate, also, that your results may not have been mine, as the following posting with the 'list' is not one I had seen, and I have been looking for a while.

Quite frankly, engine-swaps are not new to me, but most of my experience going that deep was on cars pre-computer [like my '70 RoadRunner], and the issues with this one have been 'above my paygrade', as it were, because diagnosing and fixing 'tron issues is not unlike learning Spanish - I may know the words, even some of the definitions, but my problem is building complete sentences in this foreign language, lol!
Thank you for the link to the other thread, there is a lot to unpack there, very helpful.