well i don't have any good info for you...

but, i will be considering this option soon with my 01 2.5L.
I would be VERY interested in how this works out for you.

Subscribed to thread. :banana2:

 

You'll need a new PCM for sure.. as far as the wiring harnesses - not too sure on that one. For what it's worth, I'm doing a 3.9 to 5.9 swap right now, and I'm re-using my V6 harness - the only thing that's different is wiring in the 2 extra injectors for cylinders 7 and 8. So it might be the same for you for 5 and 6?

If you want my opinion too.. the 3.9 is a step up from the 2.5, but it's still kindof a dog. If your going through the trouble of doing an engine swap, grab a V8 :drive:

Check out my thread in the 5.9 forum! There's 6 pages of info there, I started off knowing pretty much nothing on the topic, and a few weeks later I have all my info, I have the engine and the PCM sitting in my garage, and next weekend I'm doing the swap!

Good luck! PM me if you need any help, maybe I can help you out :beer:

 

yeah the v6 is kinda a dog and a gas pig.

a dakota seems a little to heavy for that v6, at only 175hp it's a bit of a slug.

v6 - 20mpg (maybe)
318 v8 - 17mpg

 

yeah the v6 is kinda a dog and a gas pig.

a dakota seems a little to heavy for that v6, at only 175hp it's a bit of a slug.

v6 - 20mpg (maybe)
318 v8 - 17mpg

20/17 is extremely generous. Either way, yeah.. the V6 in the Dakota is very underpowered.. i can't even imagine how it must feel to drive the 4 banger. It's V8 time :woot:

 

Oh C'mon it's not that bad lol. Seriously, I always thought the 3.9 had a lot of grunt to it compared to most other 6cyl engines... Gas mileage isnt the best though but I'm driving a F150 with the 300 6cyl and I got better MPG with my 3.9 but I do believe this ferd motor is a little stronger than the 3.9 but it's also backed with a 5-speed...

 

Oh C'mon it's not that bad lol. Seriously, I always thought the 3.9 had a lot of grunt to it compared to most other 6cyl engines... Gas mileage isnt the best though but I'm driving a F150 with the 300 6cyl and I got better MPG with my 3.9 but I do believe this ferd motor is a little stronger than the 3.9 but it's also backed with a 5-speed...

You're also talking about a truck that weighs a lot less than us Gen III's.

I would tend to agree with the others... going from a 2.5L to a 3.9L isn't really going to gain you that much (I've had the 2.5L, and I've test driven MANY 3.9L's) I ultimately went with the 4.7L and if I were you... I would DEFINITELY go with some sort of v8... even if you can find an old 5.2 out there... it's going to be worth it. There is a lot of work that goes into swapping out a motor... and I just don't think the amount of work will justify the amount of gain you'd get out of only going to a 3.9L.

BUT.... if you are dead set on making this happen. I don't see how it wouldn't be possible. The other poster above is right on with a new CPU... you'll definitely need one of those. As far as the wiring harness... from what I remember from owning the 2.5L... there ain't much for wires under that engine bay... I would dig REAL deep just to make sure you wouldn't need a complete 3.9L harness before forking over any money for this motor.

Paul

 

To yall saying the 2.5L is pure hell.. it is.. I have a built in need to go fast and get fast faster.. and the 2.5 just aint cuttin' it. Im planning on buying the motor from Jason (though I'm still keep options open, but its looking really good) for a very cheap and affordable price. What kind of gas mileage will I get.. I get around 24 in my truck *points and laughs at all yall with 5.9 gas suckers * By the way Red.. are you willing to sell your 3.9 pcm?

Thanks for yalls help...

[Xtrah]

 

To yall saying the 2.5L is pure hell.. it is.. I have a built in need to go fast and get fast faster.. and the 2.5 just aint cuttin' it. Im planning on buying the motor from Jason (though I'm still keep options open, but its looking really good) for a very cheap and affordable price. What kind of gas mileage will I get.. I get around 24 in my truck *points and laughs at all yall with 5.9 gas suckers * By the way Red.. are you willing to sell your 3.9 pcm?

Thanks for yalls help...

[Xtrah]

We'll see - let me see how the engine swap goes first

 

the bellhousings are different!!!!! you'd be better off doing a swap to a 4.0l out of a simular year jeep. It's the same relation ship to that 4 banger as the 3.9 is to the 5.9. The 2.5l is the same engine that came in wranglers and the 4.0 is the same motor with two extra cylinders. This engine would well eat a 3.9l stock dakota. You would also be the only one to do it. If you have your heart set on the v6 then find a trans too. The I6 would be a bolt in that would allow the same clutch/trans, or torque converter to be used. You would also be able to reuse your accessory drives and all your electronics. So find a wrecked jeep wrangler or cherokee and go to town. With the initial purchase of an engine and related parts @500.00-750.00 you could have 200hp for less than a grand total. Do the research because this swap would be way cheaper in the long run. There's also all kinds of power adders-superchargers, turbos made to run on this engine due to it being such a popular application.

 

the bellhousings are different!!!!! you'd be better off doing a swap to a 4.0l out of a simular year jeep. It's the same relation ship to that 4 banger as the 3.9 is to the 5.9. The 2.5l is the same engine that came in wranglers and the 4.0 is the same motor with two extra cylinders. This engine would well eat a 3.9l stock dakota. You would also be the only one to do it. If you have your heart set on the v6 then find a trans too. The I6 would be a bolt in that would allow the same clutch/trans, or torque converter to be used. You would also be able to reuse your accessory drives and all your electronics. So find a wrecked jeep wrangler or cherokee and go to town. With the initial purchase of an engine and related parts @500.00-750.00 you could have 200hp for less than a grand total. Do the research because this swap would be way cheaper in the long run. There's also all kinds of power adders-superchargers, turbos made to run on this engine due to it being such a popular application.

Good call! That would be sick to see a 4.0 in a Dakota - My dad's wrangler has a 4.0 5 speed, and that jeep has some balls for a V6.

 

next month i may have a complete harness for ya if red doesnt come through and a comp, best ive gottten was 22-24 on highway and 19-20 around me, i'd suggest if ur really gonna go with a 6, have the heads worked a tad and the intake manifold, with some work you could get same mpg and have same amount of power as a v8

 

Don't waste your time on the 3.9. Swap in a 5.2 or 5.9 and mod the engine before it goes in. I don't like the 3.9 one bit. I have drove many 3.9 Dakota and my 3.7 is so much faster and and i still want a V8.

 

The 4.0 would be fun.. I'll agree.. but heres the thing... will I get tons more power out of the 4.0 than the 3.9? I'm going to be getting Jason's engine for $200... if I could find a relatively cheap 4.0 (aka under $750) I'd love to go for that. Though I think yall are right about going with a jeep engine because my engine is a jeep engine... we'll see...

PS: I'd love a v8... but that just doesnt seem possible between gas mileage and price of the motor itself.

[Xtrah]

 

The 4.0 overall is a much torquier engine than the 3.9, and probably slightly more reliable. My buddy's has 167,000 miles, still runs great. There are cams available for not too much, you could easily see 300 tq. out of a 4.0, naturally aspirated. Not so much a 3.9. I love my motor, but I believe the dakota should have had the 4.0 for a six cylinder originally.

I say go for it!

 

as far as mods go the 4.0 has a huge aftermarket. Just pick up an issue of jeep magazine and you'll see the list of people making parts for it. They even stroke the things to 4.6's all the time. You'll easily beat all 3.9l daks and even give the v8's a run for the money. You can re-use the exhaust, power steering pump, a/c, transmission, clutch...... it's as close to a v6-v8 swap us 3.9er's have because of the engine family we're stuck with. If I had a 4banger I wouldn't even consider doing my v8 swap. The 4.0 has somewhere @10 different intake manifold manufactureres compared to just one for us v8 guys. Were stuck with @250hp stock with no real mods to get us better. the I6 starts out at 200hp with another 50 available with just the cam, header, intake and tB. You'd have a different setup than anyone I know. You'd also have a more interesting engine bay. People look at my truck and go "big wup, another v8 dakota".

 

I'm new on this forum, but I have owned an 87 Dak and a 99 Dak, both with the 3.9 V6. It was, "ok", but lacking in power and fuel economy. With some mods I got my 99 Dak up to 20 to 21 mpg. Better, but not good.

I'm thinking of buying a 92 Dak cheapo project truck (yeah, I know, cheapo is never cheap). The truck has been dropped (spindles in front, swapped springs in rear), it has the 5-spd manual tranny, but the 2.5 inline 4 is gone.

Do I read this post right that a 4.0L Jeep six will bolt right in place (for the most part) of the 2.5L 4-banger? That would make a sweet combo. I like the sound of a tuned inline six, and torque is what I want to haul my cycles and snowmobile. Has anyone done this swap? Any success?

 

So aside fromt he bellhousing, the 3.9 will drop in in place of the 2.5 and connect to the A535 tranny in the truck I'm considering?

The rest, harness, radiator, intake, exhaust, I can handle no sweat. In fact it would allow me to set up the truck as I like it. Plus, I'd work up the 3.9 before I'd drop it in.

I have a lead on a 95 3.9V6 engine, which in a Gen II and a 5-spd manual with a bit of engine tweaking should produce a decent runner. I'm just looking for a basic inexpensive truck.