Cummins 4BT & Diesel Conversions Forums banner

1 - 2 of 2 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Hey yall. This is my first post on the site, as i just made my account. I have a 2002 Jeep Wrangler TJ with a 4.0 straight 6 on it with about 174,xxx miles total. Me and a bunch of guys at my church are planning to go crazy on it. I'm funding the whole deal because it's mine, but they all have far superior knowledge about vehicle modification. I leave for USMC boot camp in early August, so this is essentially my graduation present from the guys. By the end of our little adventure, we aim to have a 4bt in it, some sort of lift, and 33" pro comps under it. I'm going to be all out honest here, i have no clue where to begin. I'm starting a sort of engineer's notebook so i know what exactly i have to do. I want to start this in mid May so I can show it off for the last few weeks of school. So that gives me 3 ish months of planning and buying before i even touch it. I want to know what i gotta do beginning to end so i have minimal delays. I realize some are inevitable, but as few as possible is what i'm aiming for. So what i would ask of you guys is to kinda give me the basics if you wouldn't mind, of course I am doing most of the research on my own, but i am accepting any and all help. As of right now the Jeep is stock. Not one modification on it. Thanks for any and all input and I look forward to your help with this project!
 

·
Registered
Joined
·
3,391 Posts
Welcome to the forum Garret and thank you for serving!

There's been a whole bunch of Jeep builds by guys here. I'm not familiar with all the particular Jeep nomenclature for models. First best thing to do is go to the Buildup Showcase section and scroll through the builds there to find similar model Jeep projects. Those threads often give a step by step and may also contain solutions to very complicated technical problems.

Also the General section and Tech section have Stickies at top of page entitled 'FAQ's' that are alphabetically indexed lists by BobS of past threads by subject. A wealth of info there. In the General section there's another Sticky at top of page, 'Show off your Motor Mounts' with pages of motor mount examples and suggestions. There's yet more info and Stickies in the section titled, 'Transmissions, Adapter and Transfer Case'.

Main considerations are first and foremost: PROPER GEAR RATIOS! This is the very heart of a happy and successful build. It's a product of engine RPM's, Transmission ratios, axle ratios and tire size mltiplied together.

With diesels it's a whole new world from gassers. Diesels produce almost full torque right off idle plus they're torque monsters! That means that before the chassis & running gear is rolling and has inertia and momentum working for it the torque slams into the drivetrain. With big tires and heavy weights something's got to give. Either vehicle moves or parts lose their will to live.

That means you will need stronger axles and transmission & transfer case than for a gasser. What you have in that model Jeep may work, I have no idea, but still that's a major consideration. So do your homework there. A manual is best by far for mileage and longevity.
In addition a 4BT engine weighs 700 lbs dry, plus an NV4500 5 speed weighs another 200 lbs, and that's without the adapter plate, bellhousing, flywheel, clutch and pressure plate etc. This will be a serious weight increase over your current setup so the suspension & springs will have to be beefed up.

There can be some real complications trying to get gauges to work because they're often run off the computer ECM on these late models. Various build threads for Jeeps give cluse on this.

Some other miscellaneous is that the diesel needs a slightly larger fuel supply line [about 5/16" for a 4BT] and also a fuel return line [about 1/4"] to tank. Usually your current line is the right size for the return and you just up a bit for your new supply line. Good to install about a foot of clear vinyl line right before the fuel filter to be able to check for air, water or contaminants in fuel. The whole system has to be cleaned of gas and many/most guys yank out the in-tank filter and pump, because it's prone to clogging and causing trouble later. It's necessary for the diesel fuel system to be super clean as any contaminants can not only stop the engine but may do very expensive damage to the internals of injection pump - a very pricey item.

For a 4BT diesel engine you'll do well with about a 3" exhaust. Muffler isn't a biggy if it's a 4BT because turbo quiets down harsh exhaust pulses. Oh and regarding the engine I like the Bosch VE mechanical pump because it's simplest, by far the cheapest and provides plenty of power & torque for a project like yours. Other pumps can provide the really big power if desired but VE pump works great for me.

That's a few general ideas, the real Jeep experts will give lots more details. Check out the many other Jeep builds on here for more info. Have a fun time and thanks to your buddies there for pitching in, sounds like a mighty fine crowd to me!
 
1 - 2 of 2 Posts
Top