[Seths95XJ]

Hi everyone, I am a new member to the forum but have been viewing for months. I am 17 and living in Spring Creek NC.
I have a 1995 Jeep Cherokee XJ 4 door with a 4.0L and ax-15 5 speed that is completely stock right now. Down the road I am going to build it into a rock crawler overlander. I want it to be diesel powered. I have not started at all but here is my theoretical build sheet.

Tube frame custom hybrid chassis, interior roll cage, complete exoskeleton, uni-rails replaced with 2x4 steel beams, all useless unnecessary factory metal cut out for weight reduction

42" tires
112"-114" wheel base (whatever is needed to achieve perfect 90* approach and departure angles
Approx. 3.5" lift (low center of gravity) (level control arm height)
Ironman4x4fab Front and Rear Double Triangulated 4 link kit, Chromoly tube links, huge rock bouncer Johnny joints
4.11 Currie dana 60 front housing upgraded tubes and RCV shafts w/ 1.5x ratio 4.5" lift portal knuckles 6.15 effective ratio
PSC hydro assist steering that uses double ended ram and pump from full hydro system
4.11 Currie Dana 70 rear housing upgraded tubes & Chromoly shafts 1.5x ratio 4.5" lift portal knuckles 6.15 effective ratio
King 3.0 External Reservoir Coil overs, maximum travel possible, dual bump stops at every wheel (1 air 4", 1 hydraulic 2")
Built Woody Custom Steel driveshafts with no skew angle
Atlas 2 or 4 Speed Transfer case depending on engine choice
NV4500 w/ GV, NV5600 w/ GV, or G56
Warn 12,500 winch and snorkel
Custom highest possible capacity diesel fuel cell (80 Gallons???)
Fully skid plated with simple steel front and rear bumpers, rock sliders
Entire body is comp cut but is completely sealed up from the inside "rain-proof" (hopefully river crossing proof too)

 

[Seths95XJ]

So what engine? I have a few in mind... I want huge mileage range and descent power/pep, but don't want ridiculous weight for off-road capability reasons, I think the jeep is going to weight at least 6,000 pounds depending on the engine/trans set up. I prefer fully mechanical but there are a few here that aren't.

4bt
huge aftermarket, can make plenty of torque (300+ Lb/ft), low-end but is tall and heavy (770LB) If I go this route there is a 4.5L stroker kit made for it.

OM617
descent aftermarket, can make plenty of horsepower and torque (300+Lb/ft), like revs, and is only 550 pounds but not as tough as 4bt and doesn't make as much low-end for crawling (but combined with 48 possible ratios and 6.15 axles it might not be a problem. I am leaning towards this engine because it is similar in size to the 4.0L. There are also variants of this engines that are newer and electronic but can make way more power and be converted back to mechanical easily and still make that same power. Haven't done all my homework on there engines.

Any Duramax smaller than 6.6, meaning the new 3.0 inline 6 and the 2.8. I don't know much about these but they are electronically controlled and injected and that is a turnoff for me but I am a Chevy guy so If someone here vouches for it I may consider one. I guess the 6.6 isn't much heavier than the 4bt so It might be on the table still if it will fit, but 850 pounds is pushing it.

Not a diesel but I could put a stroker and turbo kit on the Jeep 4.0 and make it a tiny turbo 4.7L torque monster?

VW 1.9 TDI ??? I've seen it before on YouTube, thoughts?? Seems like it would be under powered turning 42"s and 6000 pounds.

What options am I missing? Fill me in.

 

[Seths95XJ]

Actually I think I am going to go Mercedes OM606 24 valve 6 cylinder diesel and convert it to OM603 mechanical injection. I either want to go twin turbo or compound turbo, not sure which would be better all around. I want to go air-to-water intercooling and try for water cooled turbos. Aiming for 400 HP and 700 lb/ft with as much low end as possible. Pretty mild for what these engine are built to do.

 

[char1355]

Looks like you've been doing your research. A 4bt is definitely not a feather weight. That 4.5 L stroke kit would be very expensive for little gain. The original 4.5 4bt has a different block with a higher deck so you'd have to have custom rods or pistons or both to use the standard 3.9 block. That OEM 4.5 was never really meant for higher power levels. The big advantage to the 4bt is tons of aftermarket parts and it can make loads of low end torque. With a single turbo and stock injectors you can get above 200 HP with torque equal to a big block gas engine. With twins, power level will depend on which injection pump. The Mercedes you mentioned also has a decent aftermarket base and if size and weight are primary factors then that may be your best route.

 

[Seths95XJ]

So OM606 it is. There is an adapter kit for Mercedes OM603 and OM606 to New venture GM transmissions with a clutch bolt pattern for GM 10", 10.5", and 11" heavy duty clutches.

 

[char1355]

Those clutch sizes aren't all that big for a diesel. If you start venturing into high power they may slip. Member Eggman has upgraded his 4bt to near 300 HP. An 11" clutch wouldn't hold that. I believe he now has a 13". Stock clutch on a 160 HP Cummins was 12-1/4". Big factor will be how much torque the OM606 will produce. Probably no where near what the Cummins makes.

 

[Seths95XJ]

Maybe the guy in the video was mistaken, I haven't done that much research on clutch sizes but I thought with the adapter kit it put the standard GM clutch that was matched with the NV5600 back on there. I know the NV5600 dodge was behind a 12v Cummins so surely GMs couldn't have been that much smaller.

 

[char1355]

The Dodge NV5600 used the 13" clutch. Don't believe GM ever used that transmission. The OM606 is only 3.0 L and one tuned to around 250 HP only has about 300 lb ft of torque where a Cummins running 250 HP might be near double that torque. Those engines are totally different animals. One is a high revving automotive style and the Cummins a lower revving high torque monster.

 

[Seths95XJ]

Gotchya. Shoudl I save 165 lbs and go for an NV4500? Are the bellhousing to block bolt patterns the same for the two? How about the clutch and input shafts? What are the differences. The adapter plate is for Mercedes OM603 or 606 to GM NV4500. Would a dodge NV4500 or any NV5600 work? The 5600 is way stronger but also heavier. But it has better closer ratios and the proper fluid is more readily available for them.

 

[Snuggletough]

I never really got excited about the mercedes engines. The later ones are fun in a car, but the work and expensive and end result to put one in an offroad rig never made sense to me. I would choose an LS V8 in a heartbeat over a mercedes diesel. The V8 beats it in every way.

4BT is loud and 800 lbs. Not a good engine if you ever need to hear a spotter or you want to take in the natural, peaceful environment surrounding you. 4Bt wins in one aspect- Economy. Nothing else will ever match a 3.9 VE Cummins for fuel economy in a 5000-7500 lb rig.

Duramax is huge. The packaging and the complexity make it a difficult swap. They also weigh alot. And that weight is up high. Not where you want it. 1100 lbs of engine is a lot for a jeep. I just think it would be a poor fit.

I don't know what you have for length, but a 12 valve needs about 33-34" behind the radiator weighs 950-1000 lbs and the cool thing for offroad use is when you stuff one in a smaller SUV the engine will sit low and rear. That weight will be more beneficial than you think. Usually I see about 200 lbs more on the front and 100 lbs on the rear going from a gas 6 to a 12 valve.

Done a lot of expedition builds with SUV's weighing around 3 tons. The 12 valve is a big winner here. Always puts a smile on yer face. Power out it's ass and economy is great for what it is. usually 16-17 running it HARD and 18-19 MPG for a running average.

Most people can drive a 12 valve for thousands of miles at a time and enjoy listening to the engine the whole time. Many diesels this is not true. Some have very obnoxious sounds.

One thing I have learned after many, many diesel swaps: Small diesel in a heavy rig= Suck, conversely, Big diesel in a small rig= Smiles.

 

[Motohead1]

If you were staying automatic I would say OM648. seems to work fine here. Facebook

 

[Thegreengoblin]

Well you are asking on a primarily 4bt swap site....Guess what, I'm gonna steer u toward the 4bt. U are building a heavy truck, too heavy for any Mercedes in my opinion. U want to turn 42s don't mess around with smaller displacement. 4bt will provide more torque at a lower rpm then the Mercedes. Also the 4bt will be cheaper to build, easier to work on and be more reliable. So what it sounds like a dump truck, that's cool!!!

 

[Dougal]

Honestly in that list you're biting off more than a sponsored rig could chew. I'd scaled it back to a mostly stock vehicle with 33" tyres, recovery points/winch/bumpers, and any mods you need to keep those few things in line.

Then once you've got that far consider engine changes. Your fuel bill is going to be one of the smallest costs of operating an offroad rig that is driven hard.

 

[Seths95XJ]

@Snuggletough @Thegreengoblin
From everything I am seeing I think a modified mechanically injected Mercedes OM606 is the right choice for me. Crazy power, second best on "fuel" efficiency only to the Cummins, quiet, doesn't rattle, hardly smokes (like I care though), and most importantly it fits really well in an XJ from what I've seen with almost the same dimensions as a Jeep 4.0. Most other diesels are much taller and way heavier. You can also put a rear sump oil pan on these that levels 75% of the oil pan with the bottom of the block, great for front axle clearance. I don't think I will be disappointed with the power of this "small" diesel. I know it is small and the stock power levels are not overwhelming or as "grunty" as the 4bt but with the compound turbo set up and tuned mechanical injection set up I have planned for it, I think 400 hp and 700 lb/ft at lower RPM's than stock is totally achievable. That is about 75% of what some guys are getting out of them. Also at 465 wet weight, it is actually lighter than the 4.0 in it now!!! I have no problem with too little weight on this rig considering it will have a 12,500 winch, steel bumpers, an exo-skeleton, armor, and 1 ton axles.

I hear you about the extra weight being beneficial in some cases, but on real steep obstacle like a waterfall or tall smooth rock the extra weight that is now "up top" makes the vehicle unstable and unable to climb up or just dangerous since it is "top heavy" now. I've seen 4bt wrangler on YouTube that seemed like the entire weight of the vehicle was on the front bumper, they couldn't climb crap. I was really disappointed. I have seen a Duramax 4 door wrangler but that was a real heavy rig.

 

[Seths95XJ]

@Motohead1
That is an awesome rig! What size tires are those? If think if the other guys would see that turbo 3.0L Mercedes spinning large tires in a field they might feel differently. How much power you making? What engine mods? DO you have a thread on here?

@Dougal
Well, my plan is to finish my schooling, find a good job, (There is a jet turbine plant opening near me that will be hiring machinists in 2023, my year of graduation, for a starting wage of 68,000 a year), and then start gathering the parts to do a huge build all at once. I am trying to build the ultimate off-road XJ even if it means buying $60,000 in parts over 2-3 years. By then I should have a shop to build it in on my own and on my own time.

I am in school now for automotive (repair, building, restoration), diesel/heavy equipment mechanics, hydraulics, machining, welding, and metal fabrication. I also want to take metal-ology and blacksmithing later on.

 

[Dougal]

@Dougal
Well, my plan is to finish my schooling, find a good job, (There is a jet turbine plant opening near me that will be hiring machinists in 2023, my year of graduation, for a starting wage of 68,000 a year), and then start gathering the parts to do a huge build all at once. I am trying to build the ultimate off-road XJ even if it means buying $60,000 in parts over 2-3 years. By then I should have a shop to build it in on my own and on my own time.

I am in school now for automotive (repair, building, restoration), diesel/heavy equipment mechanics, hydraulics, machining, welding, and metal fabrication. I also want to take metal-ology and blacksmithing later on.

I'm a mechanical engineer. For decades I've had access to everything you think you're going to be using. Most of the active members here have similar skills and resources. But there are two things you are massively overestimating. The first is your spare time. Because a project like that takes thousands of hours to plan and execute properly. Which is the equivalment of years spent at your day job. The second is money. Because first you're going to be taxed on that income, then you're going to have a whole lot of living costs you never factored in.

When a vehicle ends up largely custom everything on it becomes a time consuming PITA. Everything needs research, design, modification and installation. Unless you've spend a few thousand hours designing and modelling the whole thing up in CAD before you start then you're continually going to be go working in circles changing things you've already done to fit around things you're trying to do.

Take a quick read of Randy's custom jeep build here: Here's the Descrambler
Randy started in 2008 and he's pretty much done now. His is the only project I've seen here of that ambition that has succeeded.

As for your engine goals. Calm them down a lot. Kids these days all think you need 300hp to collect groceries. Rock crawling doesn't need a lot of power, it needs a lot of control. Highly strung engines don't provide a lot of control.

 

[Seths95XJ]

@Dougal
I have read this post a couple of times since you posted it and I believe you are right. Eventually, whether I quit a job to pursue it or wait until I retire, I want to open an Automotive Customs Shop in my home town and build race cars, 4x4s, and make this possible by doing small engine work and heavy machinery mechanic-ing because where I live there is no one to work on the tractors or diesel excavating equipment and people are tired of paying people (mechanics) hundreds of dollars an hour to drive 2 hours from the nearest town then take their sweet a$$ time doing to work. I can make a living right where I live by doing mechanic work, small engine, heavy equipment, auto repair (not body), welding, and mounting and balancing tires. I just need the money to buy the equipment to do this kind of work. I actually stand to buy a neighbors old "tire and repair" shop (and the surrounding 9 acres) with all the tools and parts he used before he retired for really cheap just because he wants to see it be reopened and used before he dies and not see it go to some developer. The shop is less than 5 minutes from my house in the middle of nowhere, its been closed for 12-13 years. Once I have the schooling and the money to buy it I want to reopen it and expand it. Kinda chasing the Hennessey performance dream if you know what I mean. I know its sounds ambitious but It's what I want and nothing has ever interested me like the automotive field. I am only 17 and neighbors already pay me to do their auto work at mechanic pay because I am there. I didn't mention any of this before and you are still right, it would take thousands of hours but this is my plan. I will have a few builds for myself like this one that I will take to 4x4 events to get my name out there as a builder. I'm chasing the American dream, opening my own business and being my own boss, doing what I love, and providing a service for my community that needs to be filled, something that I could not do in any other country. USA!

P.S. I admire you for being a Mechanical Engineer, that was my plan before I decided to go Automotive and Diesel mechanics, I can do math pretty well and it is my favorite subject but I just couldn't cut college level math or 4-8 years of college. I'm getting all these degrees in 3 years and for me it made sense to get working earlier. I will be working in 2023 at age 20. Shooting for this high wage jet turbine class/job to save up money to open my own shop. The school I am in now offers an 8 week class specifically for the Jet turbine (pratt and whitney) that guarantees you an interview if you passed the class.

 

[Seths95XJ]

Just noticed you're from New Zealand, sorry if I stepped on your toes with my USA post. I don't mean to be controversial. We have freedom of speech in my country but are very quickly loosing that right. So I end up apologizing for most everything I say, especially at school unfortunately.

 

[Dougal]

@Dougal
I have read this post a couple of times since you posted it and I believe you are right. Eventually, whether I quit a job to pursue it or wait until I retire, I want to open an Automotive Customs Shop in my home town and build race cars, 4x4s, and make this possible by doing small engine work and heavy machinery mechanic-ing because where I live there is no one to work on the tractors or diesel excavating equipment and people are tired of paying people (mechanics) hundreds of dollars an hour to drive 2 hours from the nearest town then take their sweet a$$ time doing to work. I can make a living right where I live by doing mechanic work, small engine, heavy equipment, auto repair (not body), welding, and mounting and balancing tires. I just need the money to buy the equipment to do this kind of work. I actually stand to buy a neighbors old "tire and repair" shop (and the surrounding 9 acres) with all the tools and parts he used before he retired for really cheap just because he wants to see it be reopened and used before he dies and not see it go to some developer. The shop is less than 5 minutes from my house in the middle of nowhere, its been closed for 12-13 years. Once I have the schooling and the money to buy it I want to reopen it and expand it. Kinda chasing the Hennessey performance dream if you know what I mean. I know its sounds ambitious but It's what I want and nothing has ever interested me like the automotive field. I am only 17 and neighbors already pay me to do their auto work at mechanic pay because I am there. I didn't mention any of this before and you are still right, it would take thousands of hours but this is my plan. I will have a few builds for myself like this one that I will take to 4x4 events to get my name out there as a builder. I'm chasing the American dream, opening my own business and being my own boss, doing what I love, and providing a service for my community that needs to be filled, something that I could not do in any other country. USA!

P.S. I admire you for being a Mechanical Engineer, that was my plan before I decided to go Automotive and Diesel mechanics, I can do math pretty well and it is my favorite subject but I just couldn't cut college level math or 4-8 years of college. I'm getting all these degrees in 3 years and for me it made sense to get working earlier. I will be working in 2023 at age 20. Shooting for this high wage jet turbine class/job to save up money to open my own shop. The school I am in now offers an 8 week class specifically for the Jet turbine (pratt and whitney) that guarantees you an interview if you passed the class.

There is a very good living to be made repairing and servicing heavy machinery if you're talented at it. I know a guy who does just that. I also know a guy who owns a performance car workshop. Not so much building race-cars as constantly fixing and upgrading them for other people who race.

Both these guys daily drive stock Toyota hilux's. Because working on your own stuff gets tiring after working on other peoples stuff all week.

I'm not trying to piss on your parade. I'm advising you to scale it back to something achievable with a smaller budget and time-frame. Break it into incremental goals that can be done and the vehicle usable within months, not years. The time you have between finishing school and finding yourself with wife, young kids and no spare time is a lot shorter than you will ever imagine.
Everyone here was 17 once.

If you're rock crawling or other hard-core 4x4 then you're going to destroy vehicles. Make your upgrades and conversions modular so you can take them across to the next vehicle after the current one ends up beyond practical repair.

 

[Scot]

I would consider the VW ALH engine. I am running one in a 2002 Ford Ranger 2WD. With a set of injectors, a larger turbo and Malone #4 tune, it should be 180 hp if you believe what others say. I told them to turn it up as far as it would hold without having to swap rods and add studs. The truck runs surprisingly strong. I chose to run a Jeep/Dodge 4.0 bellhousing instead of Ford 3.0 or 4.0 to get the larger clutch. I ended up running an AX15 out of a Dakota after having trouble with one of the few NV3550 2WD ever built. There is a guy on TDIClub (EVguy) that builds the adapter you need and he did a Jeep (Cherokee?).