Cummins Repower ISF 2.8 for Defenders

donb

Well-known member
I have heard rumors of people considering the Jeep AX15 manual transmission too. Supposedly it is a little stronger than the R380 and widely available/affordable.

The NV3550 is supposed to be a little stronger and was the replacement for the AX15. From the info I've read the NV3550 is rated conservatively for 300lb/ft so it should be fine with the R2.8 in stock tune.

The Axis adapter kit for the AX15/NV3550 is just over $1,500.
AX15/NV3550 seem like you can get from $500 on CL to $1,500 for a reman'd version
But mating an AX15/NV3550 to an LT230 is the part I'm not sure about.
 

donb

Well-known member
Early on when trying to decide which way to go we considered the Aisin. After playing with the gear ratio calculator on the Cummins repower site the decision was made to go with the 6l80e for the 6 gear options and 4.10 diffs with a 1.2 tcase. The industry seems to be moving to more gears so that you can always find the sweet spot as opposed to being caught in between two gears and needing a split. Chris and Kevin @ Axis are working on making an 8 spd work.

This weekend we talked a lot about having stronger mainshafts made for r380's. Going to see if its possible to make an r380 stumpy trans that will hold up.

That would enable defender owners to not need to change seatbox, tunnel, floors etc and placing the engine further back eliminates the need to change the factory chassis mounts. Ie make this a bolt in. We preceive the primary market/application for these engines to be trucks that were rover 4 cyls that need either complete rebuilds or repower.

First off congrats on finishing the R2.8 conversion - I'm really hoping I cross paths with the owner and his 90 this summer/fall and get to see it in person!

I was going to ask you what axle gearing you used. I know with the 3.9 V8 I had in my NAS 90 the 4.1 gearing was fine with 35's. It's good to know the R2.8 can turn 35" tires. The UA CJ6 is on 38"s but I'm sure that rig is lighter and has lower tranny and Tcase gears: https://cumminsengines.com/uploads/.../2017-cummins-repower-profile-jeep-UACJ6D.pdf

I've been researching it a lot trying to associate prices with the different tranny options. The simpler and maybe cheapest route (depending on how much a beefier R380 would cost to build) would be the a stumpy R380. Like you said essentially bolt in Axis has their adapter at $2,200 (which could be the price of the NV3500 adapter and a good used NV3550).

Do you think a stock 200tdi Radiator and IC have the cooling capacity for the R2.8? Like you said if this could be a bolt-in for a 4 cylinder LR's and work with a majority of the existing items it would be a strong option even when adding the cost for adapters and engine mounts.
 

MountainD

Technical Excellence Contributor
So how was the drive/power of the r2.8? What would you say it is comparable too?id love to test drive one someday!
 

MountainD

Technical Excellence Contributor
I really would love to hear how an engine like this is in a 110. Thinking of making that combo. Would be a legal one.. the 6BT would get flagged where I am at unless you skirted stuff which could have bad results...
 

donb

Well-known member

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brdhmltn

Well-known member
Speaking of that, there's at least 3 people on IG doing R2.8 swaps into 110's or 90's and none of them seem to be willing to answer questions and they arent doing build threads. What's up with that? Hoarding up all the knowledge for themselves?
 

donb

Well-known member
Speaking of that, there's at least 3 people on IG doing R2.8 swaps into 110's or 90's and none of them seem to be willing to answer questions and they arent doing build threads. What's up with that? Hoarding up all the knowledge for themselves?

IDK - I asked this guy if he was using the R380 and LT230. He did respond but said he was using an LT77 and R380 :shrug:
 

rocky

NAS-ROW Addict
I know there is a shop in Canada...forget the name, putting the R380 behind it. I think that will become the preferred approach. However if the super strength version of the R380 arrives, that will be the way to go.
 

brdhmltn

Well-known member
The Canadian shop is one of the IG swaps I mentioned. There is also one in the UK (by Cummins UK) and two or 3 individuals, so it's more like 5-6 IG swaps.

I don't trust the normal R380 behind the R2.8 without evidence. My personal opinion is the mainshaft is not strong enough, and even if that is strengthened, the gears wont handle it long. So I'm glad these guys are doing it. I don't mind being proven wrong as it will be the easiest install path for a manual. Adapter costs don't necessarily make it the cheapest though.
 

bkeef

Active member
Guys will try and get pictures posted up after I get free from shop. Mine is with Ax15/NV-3550

It fits well and will take little mod to Tran tunnel but otherwise works great.

We bit a more off than normal. I have custom AC with dual evaporators new dash, and we are done my a completely new painless harness to replace the old junk rover wiring.

I go to pint who in few weeks and will have some better light. Will try and share more

It’s a Tom of work to do it right. Like others mentioned there is no real
Rod map. For now

Thanks
BK
 

Uncle Douglas

Well-known member
Callsign: delete
Most if not all questions can be answered by reviewing the Cummins install manual I linked. We didn't have the advantage of that pearl of wisdom,it was just released in January.

On transmissions, we used an automatic. The truck is anything but slow. The two other vehicles with a 2.8 mated to a 6l80e are both owned by Cummins. Those trucks both have the torque converter swapped out for a higher stall (2500 rpm) converter. Since the engine makes max torque @ 1500 and max's out around 3k we decided that didn't sound right and stuck with the stock one. The combination of the stock 6l80e, 1.2 tcase (used a d2 one and went GPS Speedo), and 4:10 gears with 35 inch tires seems to work nicely. smaller tires and stock diffs would have similar gearing. The fellow we built the truck for is still playing with shift points in the software but this transmission also "learns" as you drive it. Ie the more miles you put on it the better it works. As it is now, you do not even feel the shifts. He's switching back from the GM shifter it left here with to a Lokar because he likes the traditional/minimalist "look" more. That said, if anyone wants a Ashcroft console that is uncut for a shifter hole, get in touch as it won't be getting used. This truck was built to be wheeled so filling a 1/3 of the cabin with a console was decided against.

Engine cost is $8999.
If a Cummins auth installer like me buys it and gives Cummins the make, model, and vin we get a $300 discount (thats it) which pretty much only covers shipping from the Cummins warehouse in Tn these ship from.

Adapter cost to a rover 4cyl bellhousing is appx $2200. I gave Chris and Kevin @ Axis two trashed transmissions for templates. Contact those guys for a pilot bushing and modified flywheel, and adapter.
I'd suggest only using the heavier duty 130 clutch assembly.

Radiator/Intercooler- on your own here. Heritage Driven put an intercooler in front of the stock v8 radiator in a disco 1.

I've posted pictures of what I had made to spec but that special sauce costs $2k.

The engine ecu has the provision to controll adn electric fan. It kicks the fan on @ 190 degree's via a switched ground lead from the ecu. IE you wire up your fan with a relay and the ecu asks for cooling when the engine temp needs it.

People have emailed, texted and pm'd asking if Tdi stuff could be made to work ? Maybe, but the plumbing/hoses needed to make it work would look like Medusa's hair. Can a v8 radiator be made to work ? No. You need an intercooler and the v8 fills the entire space between the wings leaving no passage for the boost hoses.
My thoughts on this are why half ass the all important cooling system when you have a brand new everything else ? Do it once, do it right.

Wiring- The Cummins comes with its own harness and they indicate the ECU should be mounted in the engine compartment. The portion of the loom that needs to enter the cabin fits nicely through a stock defender bulkhead grommet. I placed the Murphy gauge(canbus gauge that allows you to scroll through all the functions and also displays any fault codes should you throw one) in the stock defender binnacle. Ie totally non- invasive install.

Oil filter. This one is on the installer. An oil filter needs to be where you can get to it and ideally where it can drain without making a huge frigging mess. I mounted it to the defender frame using a bracket i made up that uses one of the frame to bulkhead bracket bolts and two of the through frame crossmember bolts. This held the filter up above the bottom of the frame rail just in front of the trans crossmember.

Drive line. I mounted the tcase in the stock 97 NAS 90 spot using the factory brackets. The drive shafts I used were both solid ones, Ie not tubing like the lame ones used in defenders. The front I think was from a D1 and the rear was from a Classic. Both were front drive shafts.

Parking brake, I drilled and tapped the D2 case and used the original 1991 defender parking brake assembly.

Brakes-we used all new NAS 90 parts to include stainless lines from Rovers North. Total overkill, but make sure you have great brakes as the truck is going to move out.

Exhaust. I kept the particulate filter/cat and had a custom straight pipe made. Each install will vary here with the transmission chosen. Mine was 2.25 pipe that ran paralell to the driveshaft and then dove under right in front of the transfer case and then followed the stock route to the rear.

Fuel- I mounted the Cummins fuel filter in the same spot Rover mounted the 2.5 and 200tdi filters, on the bulkhead on the right side.

Steering- stock, had adapters made @ the steering box so I could use the universal AN fitings and then had my local Parker store make the lines. We used an adjustable panhard rod but this was because of the 3+ inches of lift the truck has. The stock steering res works fine.

That leaves engine mounts. This will vary with what trans you decide to use and what engine your truck has now. I realize not everyone has a mig and the ability to work with steel but I truly would not let this part of the conversion be a deterent. If you are using a rover trans, Chris and Kevin @ Axis will have an engine side mount that will match up with your existing chassis mount.

If you aren't the diy type, or know it will take you years to complete a project like this, send it to us.
 

Uncle Douglas

Well-known member
Callsign: delete
Sorry for the many pics, just happy with how it turned out
 

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rocky

NAS-ROW Addict
Brilliant work guys, and an extra thanks to the owner of this truck, for being the guinea pig and helping to do this right.
 

Uncle Douglas

Well-known member
Callsign: delete
The "data logger" is still installed on the truck. Cummins senior engineer for this project is able to dial into the truck via a cell phone call and review data, make programming changes etc. Initially we were having a communication issue between the engine and transmission which turned out to just be a cable. They sent us the coms box so they could communicate with the truck anywhere with a cell signal so they could see what was going on. I'm thinking that needs to go back to Cummins now that its dialed in. I realize that some here are ludites and can't embrace technology under the bonnet but go watch the video of this engine in a jeep underwater in the middle of a pond. Competely submerged for 15 mins in 12 ft of water. Never skipped a beat. You wouldn't want to try that with a LR td5. Cummins reliability is renowned and this isn't a new engine, its just newly offered as a repower alternative as its size, weight, power output, and simplistic installation, and low maint (no timing belt) make it a great repower choice.We worked/interacted directly with Cummins Corp in Indiana with questions, problems, who's doing what suggestions etc. I'm sure the others here working with these engines have done the same. Try doing that with any other engine manufacturer.
After checking around into what shops are charging for LS swaps the Cummins swap is appx $ 8-10k cheaper including our labor, and closer to 13k less if using your existing r380.
 
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