2.5 to 3.0 For The Dodge Avenger

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2.5V6 to 3.0V6 ENGINE SWAP

Basics: (Found on ASOG HOW To Sectrion)

Get a used Mitsubshi 3.0 motor from a totalled car, preferable with under 25K if possible. My 2.5 has over 60k now, and it's fine. The best option for you, if your 2.5 is gone, and you want to keep your Avenger? Get a 3.0 bottom end. I have read that some 2.5s are as high as 128k, and still going.

Simple Stuff:
A 2001 Eclipse 3.0V6 will work
3.0L Engine from a 2000, 2001 galant works - Lets just say that most Mitsu.1996-2001 3.0s should work.
You Can use JUST the bottom end of the 3.0 & It's Exhaust Header Pipes
Can, and should use the the original 2.5 ECU, and wire harness..
The A604 bolts right up to it - The bellhousing pattern is identical, the stock flywheel bolts right on

As we should know: The 3.0 is 99.9% identical to the 2.5, except certain spots have to be slightly grinded to mount some of the brackets, but nothing really big at all. You can use the whole bottom end, and the heads from the 3.0 - which are the same, and use all the other parts from the 2.5 on it, including the oil pan. Basically, the 2.5 is an underbored 3.0 block.

The 2.5 is said to come out in a day, but doing the project yourself will take about 36 hours. Having it done in a shop should only take about 13 man hours, then any other fine tuning, tweaking, and testing hours.

What do you exect to gain? Not too much, maybe 198hp or better depending on your tube intake, which injectors and engine's intake you used. It's stock rating is 200-220, official rating from Mitsubishi, depending on the year. The 2003 Stratus is rated at 200Hp. So, you're only looking at a 30/35hp gain over the stock 2.5.

This is not just a "I want to do that" kind of option/upgrade. If your 2.5 is blown, or bad, then this is the route for you. When (when is right; the wife says no trade in! - at this point) my engines goes, this is what I will have done, simply because the price won't be much different then rebuilding the 2.5. Same with boring the 2.5 "40" over (making it a 3.0), getting a 3.0 will be just as cost effective.

What ERT Says:
The 3.0 exhaust manifolds are totally different and if you use theirs you'd need to do alot more than grind a crossmember. You'd need to make a downpipe from scratch, remove their O2 sensors, and make sure the front precat doesn't hit the fans up front.

Here is what you use: (Avenger/Sebring, not sure about 1g strat)
2.5 Oil pan and 2.5 oil pickup
2.5 oil filter neck (seems thiers has clearance issues with our AC compressor
2.5 Alternator mount on the rear of the block
2.5 AC Compressor mount on the front of the block
2.5 rear manifold brackets and upper alternator bracket
2.5 drive plate
2.5 block to trans brackets (front and rear)
2.5 exhaust manifolds
2.5 upper manifold and throttlebody
2.5 idler pulley for the timing belt
2.5 cast iron motor mount (PASS SIDE)
2.5 Alternator
2.5 ac compressor
2.5 power steering
2.5 distributor and wires
2.5 water crossover (houses the thermostat)

Things you will need to know.
The front block to trans bracket needs to be modified. The bracket is cupped and the 3.0 does not have the notches in it to fit the bracket. So, grind the sidewalls ont he bracket down until it fits, leave it loose until you put the engine and trans together, otherwise you will not get it even close to matching the other hole.

The alternator bracket (lower) will not clear the 3.0 oil pump, there is a lower timing cover hole you will need to shave flat to clear it. Just grind it away and keep test fitting it until you can fit the bolts through.'

The lower timing cover will need to be trimmed as well. The lower right side near the crank has a mount for our oil pump, the 3.0 doesn't therefore the cover sticks out. Trim the sidewal flat until it fits.

GET THE GASKET FOR THE OIL FILTER NECK BEFORE YOU SWAP. That flange is the site of extreme pressure, silicone will not work. You can use felt paper gasket sheets and an exacto knife if you have to. Get this at any auto parts store in rolls.

Do not remove the lines for the AC compressor. Just remove it from the brackets in the car, and drop it down. Take a rope or something and tie it so the weight is not on the lines.

Remove the alternator and sit it on the top of the crossmember behind the engine and leave it there, easier to put in this way.

Remove the crank pulley, PS tensioner and the AC tensioner from the motor BEFORE pulling the engine. You'll thank me when you have 1/2" more room to tilt the motor.

If you use the 3.0 injectors on the Avenger, you have to swap injecor clips. They are TOTALLY different. You also have to use the 3.0 lower plenum. The injectors are shorter so the plenum injector bosses are raised to compensate for this. Try to use the 2.5 injectors in there and the fuel rail sits about 1/4 " to high. If you use the Stock 2.5 injectors, you HAVE to use the stock 2.5 lower plenum.

You have to use the cast iron mount from the 2.5. To do this, you have to remove the 3.0 unit and the 3.0 idler pulley behind it. When you do this, the timing belt loses tension, so you make usre you redo that. Take the stock 2.5 timing idler and swap it to the 3.0.

GET A NEW TENSIONER. The 3.0 unit is crap. No matter if the engine has 2k or 30k, REPLACE IT. We just finished a swap and the motor had 4k on it. The car left adn 5 min it was back because the tensioner gave way and it skipped 5 teeth in the rear head. Luckily the motor survived and we had him running shortly after redoing it all.

Inspect the timing belt. If it has rust or water stains. GET A NEW ONE.

[If you got a 3.0 from a manual] Remove the crank position sensor for the 3.0 that is under the timing cover. You don't need it and no you can't use this for a 5sp swap. Just wrap the stock knock sensor wire up and tuck it under the lower plenum.

Break in the car as you would a brand new vehicle. Change the oil after 1k.

Make sure the axle support bracket you remove from the block is pointing UP. The only way to fix it is to remove the engine or the axle itself.

The swap is pretty straight forward. Parts like the driveplate, distributor, and the torqueconverter are indexed. Meaning they can only go on one way, just line up the holes and boom... it all falls together.

PICTURE OF THE AVENGER WITH THE MISTUBISHI 3.0 (Who's Avenger's This?)

Manual Transmission More info:
I read that A whole 5 spd/3.0 swap will work, for those of you who have the I4 manual, or want a manual transmission: At that point you will need the entire 3.0 drivetrain, ECU, wire harness, and quite a few other little things. You'll need to reference the 3.0 wire harness to the 2.5 wiring schematic so you can cut and splice wires correctly.