Topic: swapping in a 4.0 in place of a 2.5, simple??

[Bigboi]

i was reading somewhere and someone claims that the 2.5 and 4.0 of the same are swappable with very little modification, i am not 100% sure of this, but i did notice a majority of plugs and connectors are alike from the same year 2.5/4.0, because if its possible, ill swap in a 4.0 6 cylinder into my 98 dakota 2.5, the 2.5 doesnt move quickly when weighed down by a trailer, and i think a 4.0 in a dakota would be pretty sweet

the main thing i see is, wiring for the ecu and injectors, if someone could chime in and give me their thoughts, id appreciate it

[Jeffy]

http://4bangerjp.com/forums/index.php/topic,11242.0.html

[sharpxmen]

never done it so take this with a grain of salt
what needs to change
 - frame motor mount location
 - wiring harness (I can't recall there was no Dakota 4.0 6cyl so if that's the case it might be a big problem when attaching to the in-cab and power distribution)
 - tach
 - radiator and fan
 - transmission and driveshaft
 - you need a 4.0L ecu, you can't reuse the 2.5L. You can't reuse your harness either, the lengths are different and you need 2 extra injectors which are not provisioned on your ECU connector, you will need a 4.0L ECU connector. You should be able to marry the 4.0L harness to your other pigtails (non engine and ECU related) but you'll need a service manual for both the donor and your vehicle.

that's what I can think of

[Bigboi]

it would be neat to have the 4.0 in the single cab 2wd dakota, according to the guys writeup it should be quite simple to swap... modify/weld mounts and says alot is the same, id just need to find a 98 4.0 2wd to pull everything from

[sharpxmen]

for '98 Dakota there was a v6 3.9L but no 4.0L I6

[Jeffy]

It might be too long to fit in a Dakota.  Even the XJ's had to do a some changes to fit them in the earlier models, IIRC.

[Bigboi]

It might be too long to fit in a Dakota.  Even the XJ's had to do a some changes to fit them in the earlier models, IIRC.

for '98 Dakota there was a v6 3.9L but no 4.0L I6

of course the dakota never came with the 4.0 I6, But being that my dakota is a 2.5, my truck should practically have a jeep badge instead of dodge

the length of the engine was my concern as well, the rear 2 cylinders may be a PITA to get to once installed, OR, some of the firewall needs to be cut, But, i will say that cummins 5.9 engines have been swapped into dakotas, SO, its got the space for it, just may need a lil modifying

[Mnkyboy]

IMO after all the work you would be very disappointed in a 4.0l, I would rather swap a V8 if I was gonna go through the trouble of a swap.

[dwtaylorpdx]

+1 You can put a magnum 5.7(360) in and likely get better mileage than the 4.0 will give you..
Don't bother with the 318 it was way down on power because of their old school lame injection on them.
The 5.7 got new fuel injection that the other Mopar v8's did not get especially the last years of the truck based Durango.
I have friend with a Durango 5.7 and a supercharger on the highway gets 22 to 25 if you kept it at 70 or lower.. NOt running big tires its his tow/travel rig not an offroader..

[Hunter02]

+1 You can put a magnum 5.7(360) in and likely get better mileage than the 4.0 will give you.. ...
The 5.7 got new fuel injection that the other Mopar v8's did not get especially the last years of the truck based Durango.

dwtaylor, could you check the numbers again? The way I figure, 5.7 comes out to 345CI. I'm not trying to pick on you. It's just that I'm interested and I want to make sure I'm checking out the right engine.
Thanks a bunch.  Hunter

[Jeffy]

dwtaylor, could you check the numbers again? The way I figure, 5.7 comes out to 345CI. I'm not trying to pick on you. It's just that I'm interested and I want to make sure I'm checking out the right engine.
Thanks a bunch.  Hunter

For Dodge a 5.7L (Hemi) means 345 ci.. and a 360 ci. would be a 5.9L.  318 was First Gen Durango.  The 5.7L appeared with the Second Gen Durango and the smaller engine was the 3.7L.

Sounds like he's got his wires crossed unless he meant to say 5.8L (360 CI.).

[sharpxmen]

dwtaylor, could you check the numbers again? The way I figure, 5.7 comes out to 345CI. I'm not trying to pick on you. It's just that I'm interested and I want to make sure I'm checking out the right engine.
Thanks a bunch.  Hunter

he's probably thinking imperial gallons, but it is better than the 4.7L Durango according to this.
http://www.fueleconomy.gov/feg/PowerSearch.do?action=noform&path=1&year1=2007&year2=2007&make=Dodge&model=Durango%202WD&srchtyp=ymm

[dwtaylorpdx]

Yep 5.9  first gen truck based Durango not the minivan with a long hood..

I've been considering a swap in my YJ, tired of no power or mileage.. (Id take the crappy mileage if it had power... LOL)

Even with my 4 cyl warmed up its still just too doggy. Especially after I finish my body metalcloak install this week..

Cheers

[sharpxmen]

I'd stay clear of the 5.9, I had a Dakota 5.9 R/T and was getting 10mpg on a good day. I also drove a Durango 5.9 for a couple of weeks (not R/T) and the story was almost the same, I was very very light on the throttle and never better than 15mpg average (and that is tops). The 5.7 sounds like a better option although I doubt that will be a gas saver in the YJ or TJ

[dwtaylorpdx]

My 4 cyl has never really broke 15mpg much unless driving at 40 for extended periods of time.. LOL So I figure if the mileage is going to suck at least it will suck for a good reason.