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Discussion Starter · #1 ·
Fellas,

I finally have an evening to when my girlfriend is to busy to force me to watch her dumb shows, so I can finally do a write up on my cummins engine swap.

The basics:

This was for my senior project to graduate with my BS in Mechanical Engineering Technology from Penn State.

I started with an 89 YJ I bought with no driveline, almost new interior, but ugly faded canary yellow paint.

I drove to Ohio and bought a 4BTA that was in a bread truck, It came with the alternator, power steering pump, turbo, aftercooler and some other junk.

I bought an NV 4500 5 spd, adapter, clutch, flywheel, master/slave, bellhousing, from a dodge ram 2500 that had a 12v cummins.

I got an adapter kit to mate the jeep NP 231 to the NV 4500

Got to work....
 

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Discussion Starter · #4 ·
more pics
 

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First time Jeep owner

I just drove my 95 YJ home, and have the SAME EXACT PLAN for it. If you can post more details about the swap, any tips/tricks you have or encountered along the way, I'd greatly appreciate it!

What's it like driving that beast? Did you throw it on a dyno yet?
 

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Discussion Starter · #6 ·
more pics

This is why welding safety is so important! haha
 

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Discussion Starter · #8 ·
more pics, sorry these are in no order
 

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Discussion Starter · #9 ·
more pics, really out of order, I just have them thrown around on my computer
 

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Discussion Starter · #10 ·
Anyway, these are just some pictures, I will try to write some things up tomorrow. Nobody was injured in the fire. we were welding and walked away from it, 2 minutes later it was lost....

I designed the motor mounts and had them laser cut and bent, I plan to make a few more sets up for sale at some point when I have some time!

I'll add some tips and things I learned as well

feel free to ask questions!

Sorry this is so short, I'm just trying to get to bed!
 

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Subscribed. What parts of the project related to your engineering degree? The design of the motor mounts for sure. Anything else?

Also I assume the swap is finished? How does it run/drive? What kind of gas mileage are you getting with the diesel?
 

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Discussion Starter · #15 ·
Heres a quick story...

I started the project in Feb 2011, we had a lot things worked out, most of our designs finished ect. ect.

I was welding holes shut on the firewall when I realized I had an ASME meeting in the next room. I hastily left the room, and did not triple check to make sure there was no hot metal anywhere.

5 minutes later the power went out in the whole building, and I immediatley knew what had happened, I ran back to the shop and it was already filled with smoke....

So long story short, the jeep, my laptop, wallet, some tools and just about everything in the shop was destroyed, luckily the enine was on the other side of the shop and was not touched.

So by the ime the fixed the shop, I had about 6 weeks, a frame, a body and a driveline to make it all work in order to graduate.... yee haw...

The main design of the project was the motor mounts, we did stress analysis and everything on them in ANSYS. We also had another engineer doing a biofuel project, so we had big plans to set the whole thing up to run on bio fuel ect. ect. but with the time constaints, we never actually ran it on biofuel, mainly because I was just to nervous about something going wrong, and killing the enine 3 days before we had to present, so we just told everyone it ran on a 50/50 mix of diesel and bio haha.

I got the Jeep done enough to drive it an hour home, no problems. Then I moved to Richmond VA for a job, and it sat at my parents house for a few months.

A few weeks ao, I drove it 5 hours down, no problems, she cruised at 70 mph the whole way, so no I'm tieing up loose ends in my spare time, an taking it out for quick drives.

It has crazy torque, it is definitely geared too low, it is very difficult to pull out in 1st without chirping the tires, and the 600 hp pulling clutch just grabs no matter what, it does not slip a bit, so it kinda drives like a tractor at the moment. I am hoping a re-gear and 35's will improve that a little.

The thing is loud! I have a 2.75" straight exhaust, and the turbo screams! I am only making about 10 lbs of boost under heavy load (5th gear pinned uphill). my EGTs dont go over 700 deg F, which is good, and absolutley no cooling issues, once it is warmed up, its sticks at 190 deg, and does not move.

I installed an air/air intercooler in the front, and just got random bent 2" exhaust tube to run all the turbo piping, and had to fabricate an intake manifold plate

The NP 231 has a super short SYE, and I put in a CV driveshaft, I dont even know who made the driveshaft, my friend at Novak wanted to try some new driveshaft, so he set that up for me, works great so far, I have never liked Tom Woods, I broke 3 on my last Jeep.

The in tank fuel pump is removed and just has a tube pickup, the lift pump on the engine does all the work.

I had to install a vacuum pump to keep the power brakes and vacuum controls, since deisel engines do not creat a usable vacuum anywhere.

Wiring is a peice of cake, you just need power to the fuel shutoff solenoid in the run/start key position, power to the stater and start wire to the starting solenoid, and it'll run.

I used a taurus electic cooling fan, thermostatically controlled and a cheapo alum. radiator off of ebay. Intercooler was off ebay as well.

It has a 1" body lift, and a 2.5" OME sus. lift. I had to fab 1.75" lift shackles for the front to level it out after the motor was in, but I plan to change that down the road.

I have not had it on the dyno, I will after I actually do work to the motor, I plan to put a 6bt turbo on it, injectors, a thing called a "killer dowel pin" in the injection pump to crank it up, hopefully it'll blow some nice black smoke. Hoping for 400 ft/lbs torque eventually.

The axles are stock for now, can't decide what I want to do with that yet.

I got 20ish MPG driving down from PA to VA, I hope to increase that a lot with new gears, it is pretty much topped out at 75 mph because the engine governor is set at 2800 rpm, I want to change the springs in the governor to get it to 3200 rpm as well.

Yes I HATED the yellow paint, I like the sahara green much better haha, but the interior is junk.

Basic tips:

You almost need a lift to fit it
Front suspension has to be beefed up a little
Plan to re-gear to 3.08s, almost a must
Air/air intercooler is much better than the stock water/air aftercooler mounted on the intake, and you can save 3" of height off the top of the motor if you ditch the aftercooler
No glow plugs on this motor
A big issue is clearance for the exhaust
Most the bolts on this motor are metric, I have found some good manuals I'll throw some links up to later

Got to get to work!
 

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Discussion Starter · #16 ·
No questions or comments?
 

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This is a fantastic swap I hope to under take some time in the future. I put it on the back burner for a while to focus on school work but I plan to start slowly collecting parts to get it rolling. Your thread is a huge inspiration! So the 12v Dodge transmission bolted right up or was there an adapter that needed to be fabbed up?
 

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Great job on the swap. I also did this swap in an 88 YJ with a th400 trans. I want to put an intercooler on mine and am curious as to which size cooler you used. 400 ft/lbs will be easy to reach without compromising the engines reliability. I hope to get mine on the dyno soon to see what it can do, so far I have just installed a fuel pin and 3200rpm gov spring.
 

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Discussion Starter · #19 ·
thanks! I still have some bugs to work out.

The dodge stuff does indeed bolt directly up. From what I gather the 4BT is the same block a the 6BT 12v, minus 2 cylinders, and a few differences in the lubrication system. There is a diference between the cummins engines and what you would expect on a typical V8. There is not a round "bellhousing" shaped bolt pattern cast into the block, but 8 holes, that are in 2 angles rows (4 holes on each side) on the back of the block. There are a number of adapter plates that will bolt to the block, there are ford, chevy and dodge versions of this adapter plate, some are clocked 10 degrees as well. If you get all the components from a 12v dodge ram, pre-97, (after 97 they switched to the 24v, actually at like 98.5 they switched to the 24v) from adapter plate, bellhousing, flywheel....ect ect, it all bolts up, no adapters.

I am curious as to what numbers you hit on the dyno with just the fuel pin and 3200 rpm srpings! Did you have an adapter plate that was clocked 10 deg for the th400? I will try to find the intercooler again on ebay. Most my research on intercoolers came up with hte same answer, use the biggest intercooler you can fit, So I found one that fit, but did not take up the whole grill.
 

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no glow plugs on this engine? what does it use then just compression? did you go with 3.08's because the power from the motor is enough to make up the undergearing? what size tires are you running with these 3.08's? did you stick with the stock D35 (god i hope not)
 
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