4BT cummins KJ??

jafstl38 · **Posted:** Wed Sep 01, 2010 11:19 am

Neighbor about 3 houses down just blew the motor on his 03 KJ after 145k on her! He was in the market for a CRD motor and said he came across a 4BT cummins motor and is toting with the idea of swapping it in! Is this even remotely possible!?

LibertyCRD · **Posted:** Wed Sep 01, 2010 11:43 am

The 4BT is a 3.9L engine. The VM CRD in the KJ from the factory is only a 2.8L. You are going to find that squeezing the Cummins into the KJ is going to be very difficult and time consuming to do.

However, IF you can shoehorn it in there, the wiring to make a 4BT run is a piece of cake compared to a modern diesel.

tommudd · **Posted:** Wed Sep 01, 2010 12:04 pm

Anything is possible you know, seen several in Jeep Wranglers, EB's and Scouts already
I mean I have personally seen a 302 Ford in the engine bay of a KJ and theres room so why not try?
Tight spots are going to be over the steering rack and front diff

Straight6Jeff · **Posted:** Wed Sep 01, 2010 12:10 pm

Ihad done some preliminary leg work on a 4BT swap. One issue will be the fixed front axle. Will definitely have to drop the cradle.

Would be a great project though! Now if I wasn't in the middle of remodeling my house and yard......

InCommando · **Posted:** Wed Sep 01, 2010 3:51 pm

I hope he goes for it. The 4bt is awesome

Vranes17 · **Posted:** Wed Sep 01, 2010 5:28 pm

cummins rock, I would do it but Id never personally feel like doing that myself.

1996xj · **Posted:** Wed Sep 01, 2010 5:31 pm

After the wife get's a new jeep and the KJ motor is worn out, Im going to look at a "6.1 HEMI" for a replacement motor !!! There are a couple company's that have been installing them in the new JK's !!!

JeepinJarhead03 · **Posted:** Wed Sep 01, 2010 5:36 pm

I took some measurements at one point for 4.7 swaps, sbc / sbf and 4bt swaps, i've seen worse constraints

it's doable, ignoring cradle, it looked to be more doable than the 302 in the ford ranger i did where I ended up having to cut the front of the vehicle and extend it 6" to avoid having to do voodoo with the radiator / fans lol

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

1996xj wrote:

After the wife get's a new jeep and the KJ motor is worn out, Im going to look at a "6.1 HEMI" for a replacement motor !!! There are a couple company's that have been installing them in the new JK's !!!

Drooooooooooool :JEEPIN:

InCommando · **Posted:** Wed Sep 01, 2010 7:53 pm

1996xj wrote:

After the wife get's a new jeep and the KJ motor is worn out, Im going to look at a "6.1 HEMI" for a replacement motor !!! There are a couple company's that have been installing them in the new JK's !!!

DOOOOOOOOOOOOOOOOOOOOOOOOOooo it!

tjkj2002 · **Posted:** Wed Sep 01, 2010 8:55 pm

The "so called" HEMI is to big for the KJ's engine bay.You would need alot of cutting and SFA is needed also for oil pan clearance.I measured :wink:

,why a 4.7 or Ford 347 swap is more realistic and still be able to actually drive it without killing the bank.

As for the 4BT that would be awesome but your going to need to get some very HD front coils made if keeping IFS,the OME 790's are not enough for that monster.If I remember right the 4BT is almost 900lbs for the engine alone.

Diggerfreek · **Posted:** Wed Sep 01, 2010 8:57 pm

MMMMMMMM 4BT

JeepinJarhead03 · **Posted:** Wed Sep 01, 2010 9:28 pm

tjkj2002 wrote:

4BT is almost 900lbs for the engine alone.

almost, i think it crates at 800 fully loaded with oil, regardless, it would be very difficult to keep the IFS with that type of weight, just look at how tight 790s are, I really don't think a "useful" ifs could be achieved with custom coils beyond the 500-600 range without redoing the entire IFS system already in place and as troy's mentioned before, cost of creating a new custom IFS system would be something ridiculous like triple that of a SFA

with no steel front, and a 4bt ignoring other circumstances, the front of the vehicle would probably sit at 18-19" with OME 790s and be all over the bumpstops in motion

however, don't let any of that stop you! regardless of how many giggles behind the scenes there may or may not be, we'd all do the best we could to help see something like that happen with a KJ

dieselenthusiast · **Posted:** Wed Sep 01, 2010 11:03 pm

Diggerfreek wrote:

MMMMMMMM 4BT

X2

My buddy here in New Mexico just did a 4BT swap into his 1980’s Chevy pickup. He can’t go very fast, but he’s averaging 30 mpg. :shock:

jafstl38 · **Posted:** Fri Sep 03, 2010 10:11 am

He is still toying with the idea of the 4bt, theres alot of fabrication thats going to be needed. I saw someone mention a 4.7 on here, isnt that a WJ motor? Would it bolt up to a 45RFE?

JeepinJarhead03 · **Posted:** Fri Sep 03, 2010 2:51 pm

jafstl38 wrote:

I saw someone mention a 4.7 on here, isnt that a WJ motor? Would it bolt up to a 45RFE?

All day long like it's wearin a thong

KJWildman · **Posted:** Fri Sep 03, 2010 6:49 pm

Tell him to "GO FOR IT!" . Look what I'm doing! Anything is possible, just tell him to take his time estimate and double it! Then, take his budget ...... and double that too! :ROTFL: