Unique engine conversion

I have a question on an idea I had for my 94 YJ. I will be taking off to the USAF soon, and while I am in tech school, I'm having a friend do a conversion for me. My question is will there be enough space and what would the recommended tranny/transfer case combo be? I want to remove the 4.0l I6 that is in it and put a Cummins turbo-diesel I6 in place of it. Any snags I may run into or just general thoughts on the subject? Thanx in advance

I have a question on an idea I had for my 94 YJ. I will be taking off to the USAF soon, and while I am in tech school, I'm having a friend do a conversion for me. My question is will there be enough space and what would the recommended tranny/transfer case combo be? I want to remove the 4.0l I6 that is in it and put a Cummins turbo-diesel I6 in place of it. Any snags I may run into or just general thoughts on the subject? Thanx in advance

Wow, that is an interesting conversion. I would definately use the rest of the drivetrain from the Dodge as well because that little YJ drivetrain just isnt going to be happy with the torque and weight of the big diesel. Anything is doable but I think this is as close as it gets to not doable. If you can wedge that Cummins in there with all its accessories, you then have to figure out how to keep it cool, then do something with the suspension to support it, then do something to the drivetrain to get the power to the ground, then your steering, brakes and frame arent going to be happy about the added weight.
Other than the above mentioned issues, it should be a piece of cake.

I figured weight would be an issue, and I had been guessin to just do the entire drivetrain from a Dodge truck 4x4. Stregthening frame and such shouldn't be a problem, and it'll have a lift done along with strengthening the suspension for support. I just thought of it one day, figured putting a diesel that's designed to move a ton or more would do great off-road in a lighter-weight Wrangler. And I would definitely have not used the AX-15 tranny or NP123 transfer case, there's no way they are strong enough for that diesel. I've been looking at torque problems since I thought of this, since that is the big change in what is delivered to the drivetrain and wheels. As a side note, I will be rebuilding the front and rear diffs/axles to handle the added power.

I figured weight would be an issue, and I had been guessin to just do the entire drivetrain from a Dodge truck 4x4. Stregthening frame and such shouldn't be a problem, and it'll have a lift done along with strengthening the suspension for support. I just thought of it one day, figured putting a diesel that's designed to move a ton or more would do great off-road in a lighter-weight Wrangler. And I would definitely have not used the AX-15 tranny or NP123 transfer case, there's no way they are strong enough for that diesel. I've been looking at torque problems since I thought of this, since that is the big change in what is delivered to the drivetrain and wheels. As a side note, I will be rebuilding the front and rear diffs/axles to handle the added power.

If you are doing this for off road reasons, I think its overkill and the weight will work against you. A diesel isnt a bad idea though but I would choose one of the 4 cyl turbo diesels from something like an Isuzu cargo truck. I discussed this with an off road friend of mine a few years ago. She dropped an Isuzu diesel into a Samari and it makes a heck of a good rock crawler combo. It still required borrowing other drivetrain components to keep from self destructing because it makes loads of low end torque, granted, not as much as a Cummins but still a good amount compared to any 4 or 6 cyl. and its much lighter and smaller then a Cummins or gas V8.

If you are doing this for off road reasons, I think its overkill and the weight will work against you. A diesel isnt a bad idea though but I would choose one of the 4 cyl turbo diesels from something like an Isuzu cargo truck. I discussed this with an off road friend of mine a few years ago. She dropped an Isuzu diesel into a Samari and it makes a heck of a good rock crawler combo. It still required borrowing other drivetrain components to keep from self destructing because it makes loads of low end torque, granted, not as much as a Cummins but still a good amount compared to any 4 or 6 cyl. and its much lighter and smaller then a Cummins or gas V8.


It's not specifically for off-road, it would also becoem my daily driver after tech school. I am not sure about using an Isuzu, due to I have not heard good things about them. My first choice would be the Cummins I6 that was used (still used?) in the Dodge Ram trucks a few years back. It's also an engine that has a good rep backing it, and I need more experience with diesels before I get one that may require a lot of maintenance or fixing. Most of my experience is in Chevy V8s used in drag cars, but the Chevy V8 is a conversion used a lot, and I would liek somethin that stands out. I anticipated the drivetrain issues, and plan on total conversion, from axles to tranny, transfer case, the whole nine yards. I'll be doin some research and seein what I can coem up with, as well as checkin back here to see what evryone has to say on the subject. Thanx for the help, and I appreciate any more you could give.