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BugoutJeep

BugoutJeep

TJ Addict
Supporting Member
Joined
Oct 31, 2018
Messages
2,018
Location
KY
I picked up my TJ 5 years or so ago to do a VW tdi swap, that turned into OM617, that turned into a 4BT, that turned into leaving the 4.0 alone, to putting in a R2.8 Cummins and then swapped the r2.8 in with 33" x 10.5" KM3s with a Genright Extended Range tank. The swap isn't complete, but it's perfectly driveable. I'm going to eventually need a lower range transfer case, better brakes, some basic armor protection (trees/brush/equipment), locker(s), and stronger axles.

I'm running the AX-15 and stock 3.07s, which will pull any hill I've tried so far with the newer released tune in 5th gear doing highway speeds.

I've lurked on the forum a lot, but never chimed in.
 
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So let me get this straight... You have a Cummins R2.8 in there?

If so, you're the first person I've ever found who actually has one in their TJ (that I've spoken to at least).

Did you install AC in it? What are you running for the radiator? Also, what kind of MPGs are you seeing?

Good choice on the R2.8 too. I rode in a 4BT once and it was so loud and obnoxious it would rattle your fillings out. Not to mention how heavy it is!

Oh... and pictures please! You're going to have a lot of people picking your brain I'm sure!
 
That's a fairly recent photo before I added a cheap coolant overflow tank. I do really like it but it wasn't cheap. I bought a kit from Axis Industries. I'm still waiting for some parts. The radiator and intercooler etc are from axis. I kept the stock ax-15 just put in a new clutch and new oil.

I'm not running ac. It's probably another $3k for it at the moment and I typically have my top and doors off over the summer.

I have no exhaust on it at all currently and at various rpms on the road it's noisy, but it wasn't quiet before the swap. I've only put about 220 mi on it so far which is an educated guess using Google maps and filled up 8.667 gal the other day. That was highway, backroads, a lot of idling to check stuff, some 4x4 stuff on the farm when I had a bunch of tools with me to work on 2 tractors, an f150 my dad has and to possibly have to work on something I forgot to address on the Jeep.

I'm not a lead foot kinda guy and find when offroad if I can't idle through something I should back up and try another route or use a winch.

I viewed this swap like going to jeep and getting the one I wanted the most, but choices in the USA are almost non existent.

I love the 4BT but I wanted something new or fully rebuilt and didn't want the downtime to do all that for a 4BT, which I think is heavy and more appropriate for a 1/2 ton type vehicle, which could be a bad ass jeep.

I started documenting the build very thoroughly but life intervened after awhile and I lost a few weeks of build time due to stuff on the farm we had to do. I made a lot of mistakes too as I'm rusty in some cases and simply ignorant of some of best practices for a swap like this.

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wow that's impressive...looks like you needed a shoehorn to squeeze it in. :D The torque on that would be amazing I bet ?
 
The torque is great which was the major draw for me. HP is irrelevant imo for a normal Jeep, but that depends on your driving style. This engine reminds me of a large V8 that doesn't require changing the entire drive train, but the fuel economy (early indicators) of some kind of small crossover hybrid.

The fit is a bit tight, but it's not terrible. In time with the EGR removed fitment will be much better. The EGR and DOC are the problem trying to cleanly route everything. The DOC forces your hand practically on engine placement. They do make brackets so you can squeeze in an AC compressor, but it was just too much money on top of everything else, considering I like to take the top off and the doors off during the summer and pick my trips.

I'm still working to install gauges, which I went with a Dakota Digital VFD3 display with GPS speedometer and DSL-1E. And I picked up some Corbeau Moab seats. I'll probably just do a straight pipe from the DOC without the OEM muffler which is banged up and I think internally it's coming apart. I'm also going to add in some HAM stuff as well and I had an ARB fridge for a bit, but out of the box it didn't work and had to return it. I plan to run an AUX battery as well, mainly just for the fridge, but also as a bit of a backup for the main battery. I really wanted to go with 2 dual purpose batteries for starting and winching and an aux deep cycle. But the budget was smashed a bit ago, so maybe in a few years.

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Here's a couple more. One of these days and it likely won't be until December when I'll have the time, I'll try to put together some videos of the install. It's mostly of me being an idiot and doing stuff more than once, but I was trying to explain stuff because in a few years there isn't going to be a service manual for what I've done.

Next big task for documentation is a wiring diagram. I've removed handfuls of wiring and more to come since removing the PCM. I'm also looking into one of the SPOD HDs to try and simplify some wiring, but the price tag is keeping me away for a bit until I can address several other areas like axles, exhaust, need to relocate front turn signals, because I destroy them and I guess an Atlas transfer case to slow me down a bit in 4Lo.

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DieselJeep said:
I love the 4BT but I wanted something new or fully rebuilt and didn't want the downtime to do all that for a 4BT, which I think is heavy and more appropriate for a 1/2 ton type vehicle, which could be a bad ass jeep.
Click to expand...

In all my research on diesel swaps, I came to find that the 4BT is actually not a great candidate for the TJ. It's heavier than the 4.0, it's old, it's loud as hell, and there are just better options out there. However, much like you said, there aren't many options when it comes to diesel engines here in the U.S. They're either huge diesel engines meant for full size trucks, or smaller diesel engines meant for VW TDIs (still not convinced on that swap either).

Ultimately I gave up on the diesel idea since it was going to be more than I'd want to spend to swap the R2.8 in, especially pairing it with an automatic transmission. I just decided to supercharge my 4.0 and call it a day. Not as cool as an R2.8 by any means, but more than enough power to make it fun to drive!
 
Yeah you're basically spot on with everything. Did you have to go to premium fuel with the supercharger? I'd looked mostly at the possibility of a stroker, but had pretty much settled on just towing the TJ and not touching it to go and play. However there's something about towing a streetable vehicle I didn't like and I was afraid of having the kick of going to premium which in my area is higher than diesel, which would mean almost never driving my favorite vehicle.

And unless you pay someone to do this swap, which could be a PITA with issues in the future ie a decade from now, it's an intense devotion to the project. I did this almost completely by myself as well with a few days vacation, several weekends, and a majority of nights after work for the last couple/few months. I'd always wanted to build something similar though so though it is work it's fun well it'll be fun hopefully looking back in a year. I'm still not done either and being able to drive it is a killer to my motivation.
 
Thanks.

As a mechanic/fabricator, I have ridden a desk for about 10 years with just a few stints here and there of anything resembling mechanic/fabrication work. And before that the doing part of those skills was more dream than reality. I'm around welding and machining on a daily basis for machinery, but I don't do any of that work physically.

The relationship of time and money is probably the harder part to overcome for these kinds of builds. And as a complete vehicle/system, I won't have the time/money for a couple of years or more to truly finish what I started and even then it's unlikely I will be finished.
 
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