Engine swap

BRL319

MEMBER
2007 DODGE CHALLENGER
2.7L
V6
2WD
AUTOMATIC
140,000 MILES

I have the car listed above that I want to put a 3.5 2007 Charger engine in. The engine is about toast. Bought the car for fairly cheap hoping I could save it but water got in the engine and a mechanic came and took apart the engine then gave up and left it out in the open telling the lady he can’t do anything (according to the lady I bought it from). I knew it might be hard to fix but I had high hopes. Well, it has been a while now and I’ve done everything I could and the engine is toast. I want to just take the 2.7 out and replace it with a 3.5 since I have heard it’s a much better engine and it’s in my price range. I am wondering #1 is it possible? Which I’m 95% sure it is but I figured I’d ask an expert just to make sure and #2 what would I need to replace on my current Charger to be able to fit and work with the 3.5 liter engine? I’m sure I’d need to replace the transmission but I’m not sure. Please let me know if you have any answers. Thank you for the help.

Saturday, December 26th, 2020 AT 5:26 PM

6 Replies

STEVE W.

MECHANIC
15,233 POSTS

Is it possible to do? Yes, but you will need to replace a lot more than just the transmission. The wiring harness is different as are the instrument panel, PCM, BCM, power systems, steering column module and a few other items that would be needed to allow the 3.5 to work. The days of simply doing an engine swap have pretty much vanished with modern cars. It can even be difficult if you use the same engine because of the internal changes they make.

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Saturday, December 26th, 2020 AT 6:25 PM

BRL319

MEMBER
3 POSTS

Thank you. So, just one more question. If you had to guess how much would you estimate the total cost of swapping all of those parts would be?

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Sunday, December 27th, 2020 AT 12:39 PM

CARADIODOC

MECHANIC
34,330 POSTS

Hi guys. Steve is right. Changing to a different engine size, and often the same size from a different year, is not a good idea, ... But there is one exception. That is switching from a 2.7L to a 3.5L. I'll have to find out the year and model, but a friend of a friend did that exact swap on his mother's car. Nothing else had to be replaced, not even the Engine Computer.

Chrysler always used to be the manufacturer with a well-known reputation for good parts interchangeability, but those days are gone now. I was really surprised a few years ago when I saw this swap when it was completed. The person doing that swap is a very competent do-it-yourselfer who has restored quite a few older oddball cars, so he knows how to research these topics. He puts together some nice stuff and doesn't cut corners.

One thing you want to look at is the flex plate and the holes or notches in it that are read by the crankshaft position sensor. Over the years, there could be three sets of four notches, or two sets the same and one set has one more or less notch. If the replacement engine uses a flex plate with different notches, use the original one to the car over with the replacement engine. If you use the wrong one, you'll have a crank / no-start. The Engine Computer counts those, along with the pulses from the camshaft position sensor, to know when piston number one is coming up on the compression stroke.

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Sunday, December 27th, 2020 AT 3:34 PM

STEVE W.

MECHANIC
15,233 POSTS

If it was done with original parts I'd love to know which years as the 2.7 has been a pain when it comes to swaps because of all the changes they made to it.

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Sunday, December 27th, 2020 AT 6:08 PM

CARADIODOC