Cummins R2.8 Swaps - JeepForum.com
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post #1 of 20 Old 09-14-2021, 09:57 AM Thread Starter
orange150
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Cummins R2.8 Swaps

How many people have done this swap, or know of people who have done it? I bought a 351w to swap into mine and after putting some build sheets together there's only about $3k difference to swap in the little Cummins. Unless I don't build the 351, then the delta is much larger


'82 CJ-8
258/AX15/D300
OME YJ 2.5"/31s
D30/D44/3.73s/Truetracs
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post #2 of 20 Old 09-14-2021, 10:59 AM
emiller35
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I haven’t done it yet, but when my 258 dies I’ll likely do the conversion to a small diesel. So I’m in the process of gathering all the info as well. Subscribed!


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post #3 of 20 Old 09-14-2021, 11:54 AM
Fourtrail
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Buddy built this Commando with a 2.8/NV3550/Dana 300. Make sure that you add in all of the extras needed for the cummins swap, custom intercooler, the swap was not as cheap as they thought it was going to be.


https://www.motortrend.com/features/...diesel-engine/


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post #4 of 20 Old 09-14-2021, 12:04 PM Thread Starter
orange150
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Quote:
Originally Posted by Fourtrail View Post
Make sure that you add in all of the extras needed for the cummins swap, custom intercooler, the swap was not as cheap as they thought it was going to be.
This is what I came up with
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'82 CJ-8
258/AX15/D300
OME YJ 2.5"/31s
D30/D44/3.73s/Truetracs
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post #5 of 20 Old 09-14-2021, 12:07 PM Thread Starter
orange150
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Quote:
Originally Posted by Fourtrail View Post
Buddy built this Commando with a 2.8/NV3550/Dana 300. Make sure that you add in all of the extras needed for the cummins swap, custom intercooler, the swap was not as cheap as they thought it was going to be.


https://www.motortrend.com/features/...diesel-engine/


Two years post bid, does he have any long term feedback?

'82 CJ-8
258/AX15/D300
OME YJ 2.5"/31s
D30/D44/3.73s/Truetracs
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post #6 of 20 Old 09-14-2021, 12:25 PM
Fourtrail
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Just saying be prepared, they ran into a lot of little things when doing the swap. Follow donscottwheels on instagram to see more pictures from the build.

80 CJ-5, 74 CJ-6, 56 CJ-5
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post #7 of 20 Old 09-14-2021, 12:30 PM
Fourtrail
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Quote:
Originally Posted by orange150 View Post
Two years post bid, does he have any long term feedback?

the mileage is nice, they have put over 10,000 miles on it in the two years since the build. Had to do a fair amount of work to get the front end to behave with the weight of the motor, heavy springs, revers shackle and stiff shocks to get it to run down the road without chasing it, but that may have more to do with the chassis than the motor swap. Also not a big fan of the vibration, said your feet fall asleep after driving for about an hour. Overall they are happy with the build compared to the really bad vibration and noise of his other conversions, scout II and Wagoneer with 4bt's in them.

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post #8 of 20 Old 09-14-2021, 01:41 PM
StoneTower
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For an emission state a 50 state legal crate motor might be a nice option. I like the idea of good mileage, but on a vehicle you don't drive everyday, it is not that important. I really enjoy my 5.0 Ford Mustang EFI swap and it is a ton of fun to drive. I can put a lot of gas in it to offset the cost of a diesel swap and I am willing to bet that my 5.0 with the NV4500 is more fun to drive than a R2.8.
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post #9 of 20 Old 09-14-2021, 03:14 PM
Jim1611
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What about the Cummins 4BT?


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post #10 of 20 Old 09-15-2021, 05:51 AM
Axhammer
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I can see where the little 2.8 Cummins would be an attractive swap in a CJ. It sounds a little expensive at first glance, but if you consider you are starting with all new components, it has more appeal. Good power while easy on fuel sounds good to me, once you get past the initial cost. If someone wants to put some miles on their CJ, this is even more attractive.

Some people are happy with the 258, others want more power, others just like to be different. I guess it depends on what kind of power plant YOU want to swap in.

If you don’t mind the cost, I say go for it. That little diesel will probably go 200K miles (or more) easily.

https://www.motortrend.com/features/...8-engine-swap/

Why do I own a CJ? I like to “Balance the wrench and the steering wheel”
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post #11 of 20 Old 09-15-2021, 06:44 AM
cglax6
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I finished up a 351w swap last fall, and I'll give you my thoughts on that...

My whole driveline was shot and my 304, T18 and D20 needed rebuild. It made more sense for me to build a reliable 400hp 351w and purchase a newly rebuilt Ford T18 and D20 than to rebuild the 304 to the same spec. After all was said and done with Sniper EFI (with Hyperspark Distributor, CD box and coil), fueling upgrades, Edelbrock top end kit #2092, CVF accessory kit, hydraulic clutch swap (you won't get a bellcrank from anything to fit without major fabrication; and honestly the swap was easy and cheap), radiator, electric fans, headers (with Jet-Hot coating), Painless wiring kit, JB twin stick, hoses, internally balanced rotating assembly and all block work, my grand total was a touch above $9k. Mind you, that was with spending $2.5k on a newly rebuilt Ford T18/D20 from Herm. I sold my 304/T18/D20 combo for $2.5k, so that offset the cost of my transmission/transfer case.

Don't forget the cost of your rotating assembly, lifters/rods, rockers.

It all adds up...but I spent the better part of 2 years planning and purchasing everything making sure I got good quality stuff at a good price...waited for holiday deals, coupons, etc. Military discount also helped out in most places.

I've driven my 351w swapped CJ for nearly 7000 miles and there hasn't been a second where me and my kids haven't had a big ol' smile on our faces. Not sure if I'd get that same feeling out of an R2.8...or even a 4BT.
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post #12 of 20 Old 09-15-2021, 07:28 AM
jeepdaddy2000
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Diesel's two big advantages are economy and longevity. They are usually about 30% more efficient than gas motors and 300,000 miles on an engine isn't uncommon.

Their (huge) disadvantage is initial cost.

If you are looking for economy/longevity or just something different and have deep pockets, a Cummins/TDI, (Mercedes or Mahindra?) swap is doable. If you are simply looking for more power and/or don't see massive miles being racked up, rebuilding/tweaking your stock setup or a swap to a gas V8 may be a better choice.

I've had diesel trucks in various forms for about thirty years and am a solid fan. My dream is to convert my 91 Bronco to a 7.3. Having a diesel powered CJ would be an extension of that dream.

Of course I also dream of owning a Mercedes 300SL gullwing...........

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post #13 of 20 Old 09-15-2021, 08:31 AM
Axhammer
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I agree that economy and longevity are a great benefit when running a diesel, however the main reason I bought my Duramax and my EcoDiesel were for the added Power. A turbocharged diesel will normally make good torque at a low RPM. The 2.8 Cummins does this with over 300 ft/lbs. Its probably a perfect size for a CJ, because it is small enough for good economy, yet, it packs a punch when needed.

Most stock small block V-8’s will make well above 300 ft/lbs torque, but they peak at a much higher RPM, their torque curves aren't flat like the diesel. It’s not that I dislike small block V-8’s, I actually love the sound of a mild cam in one at idle, but when you want low RPM torque, those little V-8’s have their place in the pecking order.

My little inline six in my CJ-7 makes a bunch of torque right off idle, that’s the reason I built it, for the flat torque curve. I would rather give up peak power at 4000-5000 RPM, to have less power, that comes in at a lower RPM, in my Jeep.

I think the Cummins 2.8 is a great choice for a CJ, once you get past the cost. That’s my opinion, and I explained why I think this way.
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Why do I own a CJ? I like to “Balance the wrench and the steering wheel”
1985 CJ-7 Sebring Red, White hardtop, 284 CID inline six (4.7) TF 999 auto
2020 JLU Black, Black hardtop, EcoDiesel, 35’s on 2” Mopar lift
View my Pontiac in my profile
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post #14 of 20 Old 09-15-2021, 09:33 AM
bob4703
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Quote:
Originally Posted by jeepdaddy2000 View Post
Diesel's two big advantages are economy and longevity. They are usually about 30% more efficient than gas motors and 300,000 miles on an engine isn't uncommon.

Their (huge) disadvantage is initial cost.
Scratching my head over this one. It would take me 100 years to drive that many miles on my Jeep and 130,000 miles to start saving on the fuel cost. Then you have to consider that modern gas engines are good for 250,000 miles or more.

My Dad and I had a conversation on this back in the 80s when he bought a Chevy C10 with a 6.2 diesel to drive a 60 mile round trip to work for the last three years before he retired. He traded a three year old El Camino that got 18-20 MPG. I figured that he would have to drive the truck for over 90,000 miles to pay for the increased price for the diesel engine and fuel minus increased fuel economy. It is the same for electric vehicles where you need to ignore MPG and look at dollars per mile.

There is the "No chit!" factor when someone "Says nice Jeep! What you got in it?"

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post #15 of 20 Old 09-15-2021, 09:44 AM Thread Starter
orange150
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Lots of great comments and opinions!
I'm in the camp where I like the low end power, the fuel economy, and the fact that it's "different". I've also just always wanted to put a diesel in it. I do daily drive my Jeep and want to take it on long(er) trips as well.
I settled on a 351w because I'm a Ford guy at heart and if I'm not going to diesel swap it I want a V8, an AMC or Ford V8.
After I put that cost comparison together in post 4 above and saw how close the delta is between the two I started to consider the 2.8 again. Who knows if I got my allowances close though.

The good thing about a typical V8 swap is that you can piecemeal the swap together which helps spread the cost out, unlike buying a crate engine, especially one like that. The good thing about the Cummins though is that it comes with everything it needs to run.

I was really hoping people would chime in that have actually done the swap.

'82 CJ-8
258/AX15/D300
OME YJ 2.5"/31s
D30/D44/3.73s/Truetracs
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