RJtx

I have been looking for a couple days now but it seems all the 4BT tread have died so im gonna try to bring them bak to see if there has been any lead ways in the last YEAR or so lol... basically what im wondering is how to intergrate the systems and what auto trans should I use? I can make motor mounts and all the brackets for everything just need to figure out the rest... and heck just to save time where could I get all the mounts and stuff? Bruiser conversion hasn't answered me in two months so im in a rut.

jtphoto JK

I think the biggest problem that has come up with the 4BT is that they can not be made road legal in most states and they are very noisy.

1978cj7jk2012

Any info you get let us know. I am very interested kn this as well

ToolManTimTaylor

4BT swaps have been around for eons (TJ BT swaps are real common) but I can assure you as a Cummins owner that the power is unreal. The things that seem to keep the number of swaps down are two things.

One is diesel has always had this shroud of secrecy as some mystical , smelly device that is noisy and gutless. The opposite is true to a point. The cummins (The 4bt) is noisy , but to me is a song of engine romance LOL. Smelly yes as the 4bt pre dates all the new emissions stuff so wah. They are sooo polluting ... NO... an older diesel's unburnt fuel and soot "rain out" of the atmosphere for the most part and do not hang around like hydrocarbons that gasoline engines produce en-masse. Gutless ... LOL nope not with a few tweaks especially the mechanical injection pump found on the 4BT.

The other issue is sourcing the engines. They are almost always found in bread trucks (Arnold's , Taystee , Wonder etc) but will have mileage ... no big deal as the 6BT and 4BT has a DTI (Dissassemble to inspect) recommended @ 300,000 miles. The delivery trucks usually had TH400 transmissions which make a killer combo and luck has it all the adapters (Duh) to make that setup happen. The thing is the pesky JK and its ever so love affair with needing to know information and communication with the BT is going to be ... Nil at best.

They are also H E A V Y soo a front axle upgrade is most certainly on the list of things to do. Rear axle shafts at a minimum as torque hates shafts and lugs LOL. The longevity , fuel mileage , torque , and the ability of putting out some rediculous power. Guys with a twin setup put out 380 Hp / 870 Tq on the edge of short life. Average decent life of 2-300K built 4Bt has a comfy 200 Hp / 425 Tq and 26Mpg range.

Hockeybomb77

Bruiser diesel in Tampa, fl do these conversions. They can help with questions

JKMARINE

You didn't even read the first post.

RJtx

so can how would I Isolate the electronics? I like the bigger body of the JK but the electronics are just unneccesary. could I rip it all out and run a basic lights, horn, crank setup or is EVERYTHING tied into the computer? is there a way to delete the engine/trans out of the equation? also I found a few cores on Ebay how often do the blocks crack?

ToolManTimTaylor

Cracking was an issue on 6BT cummins blocks with the casting number 53 on the side but that ended in model year 2000. Some 4bt blocks crack from running high boost with water/meth or propane systems that increase cylinder pressures. usually this is due to head studs that are way above what the clamping force strength is needed. It's not a bad thing but naturally the next weak thing is the block. A few 4BT's suffered from high cylinder temps @ piston 4. The last cylinder to be fed "cool" air and air would heat soak. This would prolong injection events in that cylinder raising EGT and stress cracks would form. Those days ended in the early 1990's

RJtx

what would be a good donor block? out of that vehicle?

Heholua

If I remember right, I believe AEV has done some 4BT conversions. The AEV guys are former Chrysler enginneers and I think they would know what you would need to do for the conversion.