Engine swap...what's needed

**thelastgoodbrother** · 04-09-2007, 01:28 PM

I was looking at another thread that referred to us 2.7 owners swapping our engines to a 3.5. I am interested in this prospect...since I know that I am upside down on my car and the fact that I have dumped major bread in this car already.

What is needed for a correct swap of this magnitude? My car was a fleet car, so I have ESP and a power seat. Other than that I don't know what the differences are between me and a stock SE. I see on ebay right now a 3.5L for 2100.00. I haven't shopped around yet so I am quite sure I can get one for less. Will I need a new ecu? What about the transmission, which is a 4spd? Thanks...this website is the best

**PhatPhat** · 04-09-2007, 01:29 PM

i want to know the same thing, show the 2.7 some luv mang.

**TMag** · 04-09-2007, 01:40 PM

3.5L comes with a 5spd auto, so you would have to upgrade to that also. You would also need the pcm/tcm for both. Probably wiring harness to match. Do you have a Pick-a-Part, I would look into those to find whole set-up.

**DannyC** · 04-09-2007, 01:41 PM

I'd love to put a 5spd tranny in my SXT. That would solve the B&G flash and give me better excelleration with the extra gear.

Any info on either one of these swaps?

**MooNDoGGie** · 04-09-2007, 01:46 PM

You don't need a 5sp tranny. I have a 3.5l with a 4sp transmission. I'm not sure the suspension is adequate though. You might need to upgrade that. Not sure though.

**TMag** · 04-09-2007, 01:46 PM

Originally Posted by DannyC

I'd love to put a 5spd tranny in my SXT. That would solve the B&G flash and give me better excelleration with the extra gear.

Any info on either one of these swaps?

You can swap your 4spd for a 5spd(Nag1), you would need to get a new tcm for it I believe.

**thelastgoodbrother** · 04-09-2007, 01:49 PM

So is your 4spd different than a stock SE's? If not, then I wouldn't have to do the tranny swap.

I have srt springs and rt sways...

Originally Posted by DannyC

I'd love to put a 5spd tranny in my SXT. That would solve the B&G flash and give me better excelleration with the extra gear.

Any info on either one of these swaps?

**TMag** · 04-09-2007, 01:51 PM

The 4spd is either a fleet car option only or Dodge changed it, 4spd is not available thru Dodge website, only the 5spd is for the 3.5L.

**lafrad** · 04-09-2007, 02:02 PM

I would look at:
www.dodgeintrepid.net

Do some searches... they have quite a few members that have swapped 3.2L and 3.5L engines into their 2.7L rides.

The transmission bolt patterns are the same, so there is no NEED to swap transmissions. the 4-speed will operate with the 3.5 just fine. If you don't like the tranny... good luck on the swap, i think it will be MUCH MORE difficult than swapping the engine.

The 2.7L ECM *SHOULD* be able to run the 3.5, without any real "modifications". The fuel tables (and bigger injector sizes on the 3.5) have enough room to put more fuel into the engine so it won't damage anything... a B&G flash would sort out anything that may cause issues... (that will be a custom flash though, so it may get pricey)

Manifold tuning valves and such are all "configurable" and, in the end, unnecessary. you just hook up the connections you have available on the 3.5 (I think someone said the 3.5 had 2 tuning valves, and the 2.7 had 1... just hook up the 2.7's to the 3.5's most appropriate one, and tie the other either open or closed.. whatever fits your driving style best). DON'T LET A TUNING VALVE DISSUADE YOU FROM DOING THE SWAP. They are usually there to "pad the numbers"... and the 3.5 will be a HUGE bump in performance, even without them operating fully.

This all sounds a LOT easier than it is. changes of this scale will run you into roadblocks and dead ends... but it IS do-able... and it will be a VERY valuable resource for other LX'ers in the field, if you choose to chase this path.

PS:
The 4.0L Pacifica and Nitro engines are the same "block", with more displacement as the 3.5L blocks. Maybe check into those... fnky had some advice about the differences a short while back, search for that info if you want to go "all the way".

**Cdn_Magnum** · 04-09-2007, 02:27 PM

Originally Posted by TMag

The 4spd is either a fleet car option only or Dodge changed it, 4spd is not available thru Dodge website, only the 5spd is for the 3.5L.

Thats not a true statement. All the '05 and early '06's had a 4 speed transmission in them (3.5's). The mid '06 switched to the 5 speed.

**TMag** · 04-09-2007, 02:44 PM

Originally Posted by Cdn_Magnum

Thats not a true statement. All the '05 and early '06's had a 4 speed transmission in them (3.5's). The mid '06 switched to the 5 speed.

Or Dodge changed it, which they obviously did.

**CANDYAPPLE** · 04-09-2007, 03:17 PM

Originally Posted by TMag

Or Dodge changed it, which they obviously did.

It's interesting when Russ and I and a few other SXT's (V-6's) get together to pick out the subtle differences that were made on an ongoing basis. My early '05 (Build date Aug 04- now with 9000 miles on it) has black headlights, 4 speed, black outside mirrors, fog lights N/A etc. These all changed over the model year and into the '06 line.

Cheers CANDYAPPLE

**ASU_Magnum** · 04-10-2007, 04:06 PM

with how touchy these cars are with their computers being messed with, I would be amazed if it was a straight, no problem swap.

**lafrad** · 04-10-2007, 05:26 PM

Originally Posted by ASU_Magnum

with how touchy these cars are with their computers being messed with, I would be amazed if it was a straight, no problem swap.

Don't mess with the computer.

The stock computer can *almost* run my highly altered engine.. just needs help idling due to low vacuum from the cam. a stock cam, or even just "mild", would run, without complaint, on the stock computer.

A 3.5L engine with stock cams will have a similar vacuum to the stock 2.7L (and therefore, idle fine, startup fine, and learn the adaptive memory fine). The question will be "what sensors are needed", and the Dodge Intrepid guide answers that.

i would assume, if anything, the new Engine computers in the LX's will be MORE forgiving than the old LH Engine computers.