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Discussion Starter · #1 ·
Hey all,

I've got a 2006 magnum se with 175000 miles. Its a nice car except the engine (go figure). So... I'm going to attempt to swap it with a 3.5. I'd love to have advice and hints about this but please no "you'd be better off trading" due to the fact that the car has low oil pressure once warmed up and would have little trade in value. I've got some mechanical experience and electrical know how. I've got a used low mileage 3.5 on its way.

Thanks for any advice or tips.

Silvermopar
 

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I owned a 2.7 before I got my 3.5 and it's a noticeable difference. I could feel it the first time I passed someone.
 

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You should weigh the 2.7- 3.5 to a 5.7 costs. Mines got 117k on it and I thought that once it reached 200k I'd consider putting a 5.7 in it. Always wanted a HEMI just couldn't find one reasonably priced in 08' when I bought my 07'. Just a thought.
 

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Discussion Starter · #4 ·
I did consider the Hemi, but the cost and work were far too high for me. I'm expecting this to not cost much over 2K.
 

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A 3.5 swap would definitely be much cheaper. With a 5.7 swap, you have to change a lot more than just the engine. If you're not a performance guy, the 3.5 should suit your needs just fine... and you can upgrade too. The 2.7 is painfully slow with few add-ons available.
 

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Just make sure that the 3.5 you have will fit your 4 speed transmission. Some 3.5s use the 5 speed and will not fit a 4 speed.
 

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Discussion Starter · #7 ·
Yes, the engine I got came out of a 4spd rwd 300. So I expect it should bolt in. One question though... Will I need a computer from a 3.5 car? I've read articles about this saying that my computer will work, and other articles saying that it will not. I'm wondering if the 3.5 with a 4 spd uses a different computer than the 3.5 with the 5 speed.

Its great to have people to talk to on here about this. Thanks for the advice.
 

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The PCM should work but you'll need to have it re programmed.
 

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Discussion Starter · #9 · (Edited)
Keeping cost in mind... would I be better off to buy a used computer i think they go for about $100 online or should I go to the local steelership? Or is there another option?

And I must say fireman you've got a very nice magnum in your signature. I'd like to be able to build something like that some day down the road a few/twenty years.
 

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are you swapping the engine yourself?
 

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Just make sure that the 3.5 you have will fit your 4 speed transmission. Some 3.5s use the 5 speed and will not fit a 4 speed.
A 3.5L with a 5spd will work in a 4spd car, and Vice Versus... You just need the correct 3.5L Oil Pan that corresponds to the Transmission that is going to be used(Trans Mount is attached to the pan, and you need the correct mount for that trans)... In my case, I have an 08 3.5L 4spd, that I plan on swapping in a 5spd, so to do so, I would need a 3.5L Oil Pan from an LX/LC that came from the Factory with a 5spd...
Keeping cost in mind... would I be better off to buy a used computer i think they go for about $100 online or should I go to the local steelership? Or is there another option?
Kind of a toss up really... 9 times out of 10, a Dealership wont be able to get the different parts to communicate with eachother, if they werent the ones who preformed the swap in the first place... Most cases, there will be several attempts and failures, all done while on your dime, and time... Personally I would spend the extra cash for a correct PCM that is known to be good, and then just start swapping it in from there... Way better to have as many of the needed parts as possible, so that way you arent dealing with the other hassles that would come up with using the different pieces...


For an SE, it is definitely wise to swap in a 3.5L if on a Budget... As generally the only things that really need to be swapped in, would be the engine and electronics... Whereas with a 5.7L Swap into an SE/SXT, then you gotta swap in the trans, if it isnt a 5spd SXT, the Brakes, the electronics, front struts, and more than likely the rear & driveshaft too... In that case, would be way Cheaper to start with a wreck 5.7L Donor, and swap everything over from there...
 

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Keeping cost in mind... would I be better off to buy a used computer i think they go for about $100 online or should I go to the local steelership? Or is there another option?

And I must say fireman you've got a very nice magnum in your signature. I'd like to be able to build something like that some day down the road a few/twenty years.
Either way, it will need to be flashed with your vin and for your car's options.

Thank you! I've had my car almost 9 years and it's taken me 7 years to get it where it is now.

A 3.5L with a 5spd will work in a 4spd car, and Vice Versus... You just need the correct 3.5L Oil Pan that corresponds to the Transmission that is going to be used(Trans Mount is attached to the pan, and you need the correct mount for that trans)... In my case, I have an 08 3.5L 4spd, that I plan on swapping in a 5spd, so to do so, I would need a 3.5L Oil Pan from an LX/LC that came from the Factory with a 5spd...
Isn't the bell hopusing different too? I don't know much about the 4 speed, that's what I've read.
 

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Having done this on many Jeeps, all I can say is have both vehicles side by side so you can grab whatever parts you need from the donor vehicle. You are far better off to buy a whole car, and then sell back to the junk yard what you don't use, than to have to go to the junk yard 37 times.
 

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Isn't the bell hopusing different too? I don't know much about the 4 speed, that's what I've read.
My understanding is that the Hemi 5spd, and the 3.5L 5spd does have a different bell housing, but the 3.5L 5spd shares the same bell housing with the 4spds... So Ideally, if you are swapping a 3.5L around, then those are only different via the Oil Pan mounted trans mount, so you would just need to swap on the correct 3.5L oil pan for whatever trans you are mounting... Now if you were to attempt to swap in a 5.7L/6.1L 5spd into a 3.5L, then you would need to swap on the correct bell housing, and also the correct 3.5L oil pan, should you decide to go with a trans your car didnt originally come with... Atleast thats what ive gotten from FnkyChkn(Pete's) posts... Other posts that I havent verified, have said that the 3.5L 5spds and Hemi 5spds are valved differently as well...
 

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So how did the swap turn out ?
I've been working on my 2.7 to 3.5 swap so far it bolts right in, there are a couple diff intakes so make sure you get the engine harness that comes with that motor.
The harness plugs right into trans and ecu.
The A/C compressor is different from the 2.7 to 3.5
The alternator and power steering are the same
The trans will bolt up but if the motor is a 3.5 5spd the oil pan will not bolt to the 4spd trans another cost to keep in mind 150 to 160 range
Im told the 2.7 computer will run the 3.5
Exhaust bolts right up
Motor mounts are all the same and sit in exact same holes
The upper Rad hose seems to be diff
Also the coolant line from the 2.7 to 3.5 oil cooler has to be modified
Right now im down to a issue with the starter not kicking in
All i can say is make sure you buy a motor from someone that wont cut the engine harness , the guy i bought my engine from cut my harness causing another issue
Also he took one motor mount bracket so i had to buy a new one
I have filmed the whole swap and once i get it running ill list the last few glitches i run into
I have seen some many talking about these swaps but don't see where anyone shows the final project
If anyone has a link to the finished swap please post a link
Thanks Cody
 

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silvermopar,

Have had my magnum for a year now and am looking to do what you did with the 2.7 to 3.5 swap. How did it go? Any tips? Thanks.

msperna66
 

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I have a question i have a 06 magnum with a 2.7 with a 4 speed transmission i brought a 07 3.5 with a 5 speed transmission what would i have to do to use the 4 speed transmission or 5 do i have to do to use it with the 5 speed transmission
 

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Hello all. We have a 06 dodge challenger 2.7 going to swap to 07 3.5 came out of auto. Dont have the tranny from the 3.5 or tranny harness. would I need them have both brains and full 2.7 harness. Any insight would be awesome
 

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Yes, the engine I got came out of a 4spd rwd 300. So I expect it should bolt in. One question though... Will I need a computer from a 3.5 car? I've read articles about this saying that my computer will work, and other articles saying that it will not. I'm wondering if the 3.5 with a 4 spd uses a different computer than the 3.5 with the 5 speed.

Its great to have people to talk to on here about this. Thanks for the advice.
To be safe and cover yourself as much as possible I would definitely recommend either ordering an ECM for the 3.5 because of the fuel mapping, shift patterns, and just the fact that no matter what anyone says it is a larger engine than what you’re running now. Some people may disagree and that’s cool but if I am going to dump 2 grand into a motor then I certainly want to get everything I can from it.
 
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