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Another 5.2 > 5.9 swap

10K views 26 replies 11 participants last post by  Blue93Dakota 
#1 ·
I scored a 2K Dakota R/T motor/trans/rear/Computer with a MP computer to boot! I haven't seen them yet, but are there any visual ques that denote an R/T drive train, vs a regular 5.9/auto/9.25 rear? I'm also looking for any pointers for when I drop the 5.9 into my '98 Dak Sport 4X4.

Planing on freshening up the motor with new rings, Bering's, gaskets...besides the MP Magnum book, are there any other resources for modding them? I'm assuming it's easier to put in headers while the motor is out, so will be looking at that while I am doing the swap.

TIA, and feel free to direct me to any threads that would be relevant.

j
 
#2 ·
it's not going to bolt in. sorry.


the R/Ts are 2wd only. you just said yours is a 4x4. you're going to have to do an axle flip kit to it in order to make the rear fit, because 2wd Dakota's are spring under axle, the 4x4s are spring over axle.

the R/T rears are all 3.92 ratio with an LSD in the 9.25" axle. that's the only difference that pertains to R/Ts otherwise the 5.9L motor and trans are exactly the same as any other 5.9L of the same year. sucks doesn't it! sorry man, nothing special about the R/T drivetrain other than the gearset, and the 5.9L motor. and you can option up to the gearset in any of the trucks if you wanted to.

now, if you just want the motor, it will drop right into place where your 5.2L sits, and probably don't even need an R/T PCM or the MP one unless your 5.9 has other mods to it like headers, intake, etc.

the 5.9Ls respond well to the "simple" bolt ons while it's out of the truck--intake manifold, headers, camshaft, computer tune, shift kit in the auto trans, etc. you should be able to make 350-380 hp if you pick the right cam and work with the right aftermarket engine tuner like Sean at SCT
 
#3 ·
I was just excited about the 5.9 :woot: the rest is a package deal the guy won't part. I was actually talking with the guy about getting me the people that called him looking for the tranny, and maybe the rear end :D hell, If I could sell the tranny for 3-5 bills, and the rear end for a couple, I'd be just fine with that.

My plan is pretty simple. Simple bolt on mods to bring up torque as I would like to use the truck for towing my Duster and Demon to the track for weekend play. As I understand it, if I swapped in the 9.25, I would have to change the gearset in the other the front Dif to match, correct?

Hmmm...3.92 gearsets...I think I could handle that :D

j
 
#4 ·
yes, if you swapped gear ratios on the rear axle, you need to match it up front or you'll tear shit up.

now, don't expect that rear axle to just bolt right in. you need to do an axle flip kit to it to get it from 2wd config to 4wd config. the 2wd trucks have a totally different suspension than the 4wd trucks, coil springs vs torsion bars up front, and spring over axle vs spring under axle in the rear.

you would need to cut and relocate the spring mounting pads on the axle to move them from the bottom, to the top, so that you can take that 2wd axle and put it into your 4wd truck.
 
#5 ·
So, got the parts home last night. It is indeed a 360 as denoted on he block, so YAY for me! It is complete from the plastic intake hose to the output shaft of the trans. Forgot to ask if he had the drive shaft tho...oops. I got two computers along with all the connectors cut off with about 3"-4" of wire for a pigtail. Their plan was to send the pigtails off to a place that would make a harness for the car they were going to put the drive train in. Now, that got me to thinking...if I can find that operation, I should have them build me a harness for my Demon :D

Now to the questions...

Computer: Is there much of a difference between the '98 5.2 and the 2000 5.9 computer wise? Where is it located?

Harness: is there much of a difference between harnesses from '98-'00, and 2WD-4WD?

What should I prep for for aftermarket goodies like headers, intake, cam, and the like? This is going to be for towing more than racing, so low end torque is high priority.

Thanks :D

j
 
#6 ·
The computers i am pretty sure look and work the same, it's just the tune. The 5.9 would have a different fuel/spark/timing curve than a 5.2, etc. You could have your 5.2 computer tuned and it'd work..but, i think it'd be cheaper to just use a 5.9 Computer off the bat.
 
#8 ·
It was by accident but I have a 5.2 computer with my 5.9. It runs fine.
 
#7 ·
not if he's going to use an aftermarket cam, intake, exhaust, etc in which case, he wants to go with Sean at Hemifevertuning.com and go with an SCT tune.

the fuel maps and timing curves are probably close enough that the computer won't know if you're running a 318 or a 360. afterall, there is no mass airflow sensor. just Manifold pressure, throttle position, crankshaft sensor for RPM, and O2 sensors for the air/fuel ratios. the 318 computer will work fine on a stock 360.

but, you can also go with SCT and get a program written for your specific 360 with whatever mods you do to it, and load it onto your stock computer. then you can use your stock computer and wire harness, and everything will just bolt right in.
 
#9 ·
A friend of mine has done 2 of these swaps now...one in a 98 grand cherokee and just finished one in a 00 durango and has never swapped the ECU...we let them isle up to temp shut it down drink a soda...then start them back up and burn the tires off...but a tune I'm sure would help greatly
 
#11 ·
Stick with stock manifold. M1 raises tourqe curve. I'd go with a 50mm tb for towing
 
#12 ·
This is the rear end I have...
 

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#17 ·
Kool...I forgot to look in the glove box when I left work LOL

But, the general concensus is, the 5.9 should slide right in, and changing the computer is an suggested option. What I might do, is find another computer, and send that in to have it flashed for the 5.9.

j
 
#18 ·
really good chance u have an 8.25 rear, if u have a 9.25, pull the diff from the r/t rear get new bearings and clutches, and swap into ur housing and boom u havve lsd,

as for motor drop it right in, use ur harness and ecu, and drive it, sell the mp ecu, sell the trans, and sell the rear if u cant use the diff and make some money back, i know that mopar ecu will sell on here fast
 
#19 ·
Getting the money together to get the 5.9 freshened up, so I can do the swap. I'm hoping to have the motor ready to go by the end of summer. My rear end is howling, so I hope to have that done soon, very soon.

What is the best way to get more torque out of a 5.9 Magnum? The plan is to use the Dak as a two rig for my Duster and Demon.

j
 
#20 ·
If you want towing torque... Then leave it fully stock. The factory built these for just that, low RPM towing torque. No intake out there is going to out perform the stock kegger intake in that arena, unless you custom build some sort of small block crossram intake reminiscent of the old big block cross ram packages

Long tube headers might help over the stock exhaust manifolds though.
 
#22 ·
You should be able to use the computer that came with the 5.9 unless one of them has that security system crap, then that would need to be flashed out. Use the wiring harness that is in your truck now. You have the 8.25 rear. Find out what ratio you have. If you want help towing go to a 4.10 or 4.56 rear depending on tire size. As mentioned above the stock set up should be fine. If you wanted to spend some money you could upgrade the heads and put in a different cam, but I don't think it would be worth the money. If you really wanted to spend some money, you could stroke it, but I don't think that's what you are wanting.
 
#23 ·
I have 3.55 gears now, and the 9.25 rear has 3.92, so that will help. I'm looking at probably just a cam, and maybe a TB change, with a flash on the PCM to accommadate. If I give the specifics, mostly stock, cam specs ( Something like the Comp Cams 254HR12 ) , stock tranny/converter, 3.92 rear, 33" tires, will a custom tune be all that I need? Also, is a PCM tune going to accommadate the different diameter tire, and keep the speedomoter correct? Some of the questions I keep coming up with in my head.

Finding out just how much I DON'T know in this swp LOL

j
 
#25 ·
They can tune that I believe. I have OBD1 so I'm stuck changing pinion gears in the trans.
 
#26 ·
Is there a connector I can attach to my laptop, and a program that I can use to adjust, and/or fine tune my PCM?

j
 
#27 ·
Not that I am aware of. GM has that and so does Ford. Not sure we can do that. Even so, I don't think that would be safe unless you really know what you are doing. With SCT or other handhelds you can adjust certain perameters, and some people can send you a tune. I'm sure for the right price you could get the software that allows you to tune it as well, but not sure how much. Unless you are going to be doing it as a business, probably best to leave it to the experts. I thing B&G performance can hook you up with some software, but not sure it's what you need for what you are doing. Get in touch with Sean (Hemifeaver) and see what he has to say about the tuning. For what it sounds like you are looking to do, he should be able to get you there for the lowest cost. He helped the guy that bought my 410 stroker. We pulled a 5.2 out of a truck just like yours and dropped it in there in one weekend. He already had the SCT loaded with the new tune and it fired right up and drove. A few calls/notes back and forth and he was good to go.
 
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