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Diesel Engine Swap, Discuss...

erikrs301

NAXJA Forum User
So my 4.0L has 257K on it and will die someday. I have an AX-15 and NP231 also original. This is a trail rig, but may be driven a few hours to the trails. Questions...

- What all would be involved with swapping in a deisel engine?
- What engine would be best?
- Scrap or keep AX-15/NP231 combo?
- Is it worth it?
- Give some budget and unlimited budget options?

Please keep your, "just get a Stroker" or any other gasoline engine swap related comments out of this. I know just throwing in a new Jasper 4.0L would be much easier and cost effective. ;)
 
my first concern would be the weight of the diesel .. i dont think the unibody psuedo frame would be able to handle it without a whole lot of reinforcement... xj's did come with a diesel at some point but from what i remember it was nothing spectacular and was quite small.. oh and just FYI .. the aw4 doesnt like to shift right with anything other than a motor that once came in front of it ( another 4.0l etc etc )
 
I know in CA, from CARB smog perspective, it is right next to IMPOSSIBLE to do put a diesel engine in a gas chassis. The reverse is much easier, but not simple by any means. Don't know about your neck of the woods.

For off-road, diesels are not the best for the type of wheeling we do out here. You need quick throttle response, and a diesel is not good at that at all.

If you were set on one, the one to have would be the VM 4 or 5 cylinder diesels used in UK spec WJ's. From what I've heard, they are quite nice. They are made in Italy to DC specs.

They are, of course, not certified for U.S. over-the-road use, so it would have to be an OHV vehicle for the rest of it's life.

CRASH
 
Basic EPA regulations for an engine swap for a vehicle to be registered for on-highway use:
1. The engine must be complete with all its original US emissions systems.
2. The engine must be same age or newer than the chassis.
3. The engine must have been offered by the manufacturer for that MODEL of vehicle sometime during the vehicle's production run.

Even a new KJ diesel wouldn't qualify, since it was never offered in the XJ chassis.

So, you're screwed on getting a street-legal diesel (unless you go thru the enormous effort and cost of getting an EPA Certification).
 
Yes, those are pretty much universal rules. Good post, RixXJphx

CRASH
 
Ya I would say go for it. The frame is going to have to reinforcement to it. I would look at a Turbo Diesel from a Dodge Ram in a juck yard. They are inline 6's. They might measure out to be the same length as the 4.0. Now with this engine would come custom motor mounts, rad. wiring harness. You could get the transmission out of the Dodge truck as well. Super beef. You might have to get a adaptor for the t-case, not sure. But if the only thing your going to use it for is trail use. I would look into it. But first thing is to get all the info needed for the swap from your local DMV. If they would allow a OHV to have a diesel and it can be done within the law. I say hit the bone yards and start figuring out what you need. Also a place to call would be Banks. They do diesel stuff. Juice
 
Interesting. What about a small Mitsu unit, out of a small box truck, or maybe a little 4 cyl Cat? You MAY be able to work around the emissions by classing it as "experimental" or change it to a "truck". Let us know what you do...I am excited for you.

Rev
 
I don't know if I'd actually do this. If my 4.0 lasts a couple more years and I have the CJ done, diesel may be an option. If the engine goes, everything is getting gutted, hacked, caged and re-done.

PA has a Special Construction title, it could probably be re-titled as one after all is said and done. Otherwise I guess I'd have to get a trailer for it.
 
Ya I would say go for it. The frame is going to have to reinforcement to it. I would look at a Turbo Diesel from a Dodge Ram in a juck yard.

Have you ever actually seen or dealt with a 5.9 liter Cummins Turbo Diesel? They weigh about 950 pounds, dry. When I rebuilt the one in my brothers truck, it cleared the radiator mount and firewall by exactly 1/8". The engine is also VERY tall, owing to the deep skirt block.

They are a very good engine, bot to put one in an XJ, you would need about 14 inches of lift to clear the oil pan, and one helluva hood scoop to clear the intake manifold and valve covers.

CRASH
 
Rev Den said:
Interesting. What about a small Mitsu unit, out of a small box truck, or maybe a little 4 cyl Cat?

I'm thinking 4 cylinders is all it should need as long as it's a big enough 4 banger. 6 would be nice bu the weight would probably be killer.
 
CRASH said:
Have you ever actually seen or dealt with a 5.9 liter Cummins Turbo Diesel? They weigh about 950 pounds, dry. When I rebuilt the one in my brothers truck, it cleared the radiator mount and firewall by exactly 1/8". The engine is also VERY tall, owing to the deep skirt block.

That's why I'm thinking a 4cyl...although a custom 10" high cowl hood would be, uh, interesting to say the least :D
 
Have you looked for an 84-85-86 XJ diesel? they are not horrible, but they are underpowered. It's easy to "massage" a diesel, though.

CRASH
 
Look in to a four cyl. Cummings. Case uses them in construction eq. skid loaders etc. I looked in to putting one of those into my 88 xj, but it was too much fab work, motor mounts tranny adpters and the like. A friend of mine put a TB6 industrial engine (the 6 cyl version) into a '79 F-250. He fabed all f the mounts and adapters himself took all winter, but it worked out very well. 45 mpg over the Divide in overdrive!
 
diesel

I think that as someone suggested the mitsubishi truck might work well. I would steer clear of the VW diesels as they severely lack torque (I drove a diesel Rabbit for years). I know that the 4 cyl cummings are good but don't have any advice as to what tranny would make a good match. Good luck and show us the finished product!
 
A Friend of mine talked about putting a diesel in his TJ just to make it one of a kind. He was looking into a 3 cylinder motor, the way he talked they make adaptors for tranny, etc. BUT that was a TJ, I'll ask where he got his info tomarrow, but I would think you would be able to find info doing a search on the net.
 
The 3.9 liter, 4 cylinder cummeins is shorter than the 6 cyinder, and it would fit into the engine bay, lengthwise. However, they are just as tall as the 5.9.

They weigh ~625 pounds, dry, depending on accesories. They can be massaged to make 500 ft lbs of torque, so they would really scoot your cherokee around.

Last time I checked at a Cummins dealer, they were $6,200 for a re-manufactured unit, plus core.

They can be found in some UPS and Fed-Ex rigs, and also some E-350 Ford box vans from the 1980's.

CRASH
 
Dreaming you say.....always wanted a 2.3 ford turbo cause the 2.3 is super cheap and easy to build (friend of mine races ministocks and turns 8k every weekend makes est. 200hp, you wouldnt need anything that wild but stock with turbo makes ok power. What I really want to do is go full electric motor. Looks like it would cost up to $6-8 grand but that would be full torque as soon as you hit the throttle. Never add gas or oil and you could always hear your spotter.
 
yellowxj said:
Dreaming you say.....always wanted a 2.3 ford turbo cause the 2.3 is super cheap and easy to build (friend of mine races ministocks and turns 8k every weekend makes est. 200hp, you wouldnt need anything that wild but stock with turbo makes ok power. What I really want to do is go full electric motor. Looks like it would cost up to $6-8 grand but that would be full torque as soon as you hit the throttle. Never add gas or oil and you could always hear your spotter.

I have one of those in my 79 mustang pace car(had it since I was a teenager) ... :D

it is a dog... I remember geting beat of the line by escorts... :D :D

but that could be because my number one piston skirt was laying in my oil pan.. drove like that for 30k miles :D.

I don't think that would be a good option for the XJ..
 
suprised nobody has brought up mercedes. An old 5cyl mercedes might fit well.
 
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