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Discussion Starter · #1 · (Edited)
I have recieved alot questions regarding the build of my Cummins powered MJ, so I figured I could post the specs to help anyone interested in a MJ/XJ vehicle conversion. Here goes:

1992 Comanche MJ 4x4 shortbed
1993 Cummins 4BTA 3.9l Compound HX30W/HX40W, VE pump-turned up,366 spring
2000 Dodge Cummins NV4500HD trans, adapter plate, transfer case input gear
with 13 inch clutch and flywheel conversion
1996 Cherokee XJ 4.0l/AX15 clutch master, slave and line
1987 Cherokee XJ Dana 44 Semi floater-Trutrac diff,Superior shafts,ZJ discs,3.55 ratio
1992 Comanche stock front axle with Trutrac diff,297x shafts,3.55 ratio
7.5" inches of lift- 8.5" inch Rustys coils, settled 1" inch, Bilstein 5150's,
TnT Customs Y Link long arm front suspension with modified bellypan to clear
NV4500 trans/ HD rear spring with spring over axle conversion
Custom track bar and cross over steering conversion
New process 240 series transfer case from 4 different donors with factory
fixed output from pre 94 Dodge Ram and 1330 2 piece, non cv rear drive shaft
3 core radiator with tripple 9 inch electric fans, 205 on 195 off
One half of a 6.0l Ford Powertsroke intercooler core with Ford F700 end tanks
and 3 inch plumbing
open mandrel bent 3 inch exhaust and Powerstroke K&N filter
94 to 98 Dodge 12 valve intake horn shortend 1.250" on cut down 4BTA
base, with fliped intake plate for hood clearance
1994 GMC Astro AWD power steering and hydroboost system w/ZJ prop valve
33x12.5 Goodyear Wrangler MTR's on polished 15x10 Eagle Alloys

I have been using this truck as my daily driver/trail rig/tow vehicle since august of 06, and I love it! It gets 28 mpg average, pulls 6k lbs with ease, likes foot deep mud and NO problems keeping up with highway traffic. I beat this truck like I stole it every day, and I swear it likes it. I have lots of pics, If I can help any one in any way, feel free to ask. Don Bankston
 

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Very cool truck! :)

Two questions: How did you have the Ford intercooler shortened, and what gears do you have in the axles?
 

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Nice engine and turbo colors. Looks identical to mine. My intake came so close to my hydroboost that I had to slightly rotate the reservoir. Is that why you cut your intake horn down? Looks like the main difference between your's and mine is the turbo and maybe the injectors.
Some other Q:
1. What are your boost levels at?
2.Think about running it on a dyno? Curious how your H1C run against my HY35W and Bosh 190's seeing we have almost everything else the same.
3. How far did you turn up your pump and what settings did you turn up? Mine is just short of runaway on full fuel and I only smoke for a very short time during hard acceleration.
4. What's your overall vehicle weight?
 

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Discussion Starter · #4 ·
Mikel, any intercooler or radiator can easly be shortned top to bottom, its length ways where you have to weld a all the small circles around the core holes. The ford intercooler just happened th be the correct witdh vs depth to sqeeze between the header panel and the grille. I centered it on the radiator, placed my end tanks, and fabed the space between with 1/8 inch aluminum plate, and tig welded it together. I used to run a driveline dpt in a Ford dealership, so I saw alot of 6.0l Powerstroke intercoolers split the plastic end tanks, replaced under factory warranty, so I already had the intercooler core lying around. The axles have factory 3.55 ratio, which puts RPMs at 1810 at 65 MPH, verified with a digital tach and gps.

Drivers, I cut the intake horn down for hood and brake booster clearence, which it gave bearly enough, about 9/16 of an inch, same as the #1 valve cover. This is just enough for the intake horn paint to scuff the under side of the hood on the 1/2 powershift during my frequent burnouts. I am using first gen Ram 6BTA mounts, with 3/16 steel plate formed the frame rail and secured by six 13mm factory bolts, so far with good luck, given my record for abuse. I would love to dyno the truck, do you know of any place or events in western PA or NE Ohio to do so? Presently the pump mods are: smoke screw-1/2 turn in, AFC spring tensioner-1/4 down, max power screw-2 turns in with factory tack welded collar in place(washers removed), factory aneroid pin at deepest setting and 3200 RPM Governer spring. Before the pump mods the most boost I ever saw was 14 psi, after mods 25 psi max, with egts under 1000 deg post turbo, how do these numbers compare with yours? I will be installing my 12cm3 exhaust housing as soon as I can find time to finish my one peice rear turbo blockoff plate/downpipe. Factory exhaust parts will not fit in the space I have left. I am very curious as to how much power I am making with my modest settings. The truck weight is 4040lbs with a full 17.5 gallon fuel tank, bucket seats, and all power interior. What does yours weigh?
 

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I would love to dyno the truck, do you know of any place or events in western PA or NE Ohio to do so?
We definitely have to hook up and compare trucks. I live in N.E. Ohio. I have a dyno place in Ashtabula, Ohio where I go. He charges $50 and is preparing for a dyno festival of some kind real soon. I will find out. He said there was a TChevy Duramax that did not smoke at all last year at his event and put out some monster numbers.
The axles have factory 3.55 ratio, which puts RPMs at 1810 at 65 MPH, verified with a digital tach and gps
I see how you are getting 28 mpg. I avoided this rpm at highway speed because it had more vibration there. I went up to 2000-2100rpm at 65 mph to get into a real smooth running zone. The HY35W plus the pump advancement lets the engine really come alive there. My max torque is at around 2100rpm and the high h.p. is right after that on the curves. I knew I would sacrifice some mpg put my priority was to make a strong tow vehicle for my 4,500 boat and maybe a camper on top of the bed.
pump mods are: smoke screw-1/2 turn in, AFC spring tensioner-1/4 down, max power screw-2 turns in with factory tack welded collar in place(washers removed), factory aneroid pin at deepest setting and 3200 RPM Governer spring.
Mine are: smoke screw-dono. Don't know if I got it back to original starting point while screwing around with it one day.
AFC spring :close to all the way down; maybe 1 turn short of all the way down.
max power screw- just turned in until I reached the unstable point and backed out 1/4 turn. I would guess that's three turns in.
tapered pin-At max taper. Left it there after the last dyno. Fun factor keeps me from turning it off maximum fuel setting.
3200 spring- Check. It's in there on mine too. Best $ I spent yet next to the no $ to just rotate the pump.
I was at 27 psi max but dropped one psi after i inserted the intercooler. EGT's are the same as yours. I have not run it in hot weather or towing conditions since I put the intercooloer on. Want to see how much higher it goes.
I really want to dyno mine again because the power went up a good amount after adding the intercooler. Would be nice to share the intercooler H.P. and torque increase numbers here at this site.
What does yours weigh?
- I think I'm up around 5-6K. and that's before I fill the 30 gallon tank. I think the pumps are on summer fuel now. My fuel numbers are looking better on this tank. Did most of my improvements this past winter while we were on winter fuel so i don't have a good mpg yet. It looks like it will be about 400 miles at the half tank guage reading; approx. 25-26 mpg with the turned up pump and my 3.55 gears and 31.6" tires.
Know of anyone else in our area running the 4BTA?
 

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Discussion Starter · #6 ·
I have not seen or heard of anyone localy running , or intending to convert to a 4BT. Most people shy away due to the cost vs a low tech/cost small block conversion. Thats fine by me, it keeps our trucks unique.
 

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sweet jeep!

what's with the 2-piece rear drive shaft? your wheelbase isn't all that long....

oh, and you need some bigger tires :D
 

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That is VERY nice. I like good clean work. You kept everything neat and wound up with a super sweet ride. Ive been apart of two builds, one in a YJ and the other in a Chevy. Yours is by far the cleanest compared to the ones Ive been apart of. Im about a year away from finishing school to become a trades/mech teacher. I plan to do several diesel conversions, I hope they turn out looking like that.
 

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I Like!!:D
 

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Lift?

Was the lift required for fitment of the motor or for off-road function?

Would a 4BT fit into an unlifted Comanche/XJ?
 

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Always good to see some more Jeeps! Thanks for sharing......looks good.

Do you get the "you know you're filling up with Diesel" inquiry at fuel stations too?
 

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Nice Job!! I didn't notice a battery under that hood compartment, where are you running it, or am I just not seeing it? Also I am planning on doing a intercooler installation on my rig so pics of that would great if you could.
 

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Diesel DYNO Day in Ashtabula Ohio

This Saturday is the DYNO Day for diesels. Hot Dogs and Bergers served. $45 for three pulls. More question here.([email protected]) or ask me to forward his invitation. I will forward it.
 

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That is one sweeet jeep!! Looks nice under the hood. My vehicle should be done in the next couple weeks. (82 Chevy silverado 4x4 nv4500, 3.9)
Just curious to where you are located in western pa. I live up by Erie, Pa.
 

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Discussion Starter · #15 · (Edited)
Durango, I should have been more specific, I ment 2 pc slip stub drive shaft with no cv/double u joint at ethier end. I have seen way to many 1310 and 1330 cv's fail under hard use, and the 1350 cv's cant run the angle I needed.
Av8r, When I first started the swap I found that the engine would not fit between the hood, firewall, steering and track bar at the same time. I had a front 4.5" short arm lift on the shelf, that turned out to be what I see as the minimum lift to clear the oil pan and still have decent suspension travel. But when I beefed up the rear spring and went spring over, the truck had a slight "sport rake", so it took 3.5" more to level it out. the TnT Cutoms Y-Link was just the icing on the cake for travel, road manners, high ground clearance, and exhaust routing room.
tndonor, There no mistaking this thing when its running its a diesel. When poeple see me at the diesel pump the come right over and check it out.
jeepcummins, I put a sealed Optima behind the passenger seat on a custom mount with high grade welding cable. I only have one Intercooler pic from during the paint process, I will try to get more posted.
Driverswanted, I am IN for saturday! Forward me any info you can. I would really like to see you truck. I am only an hour from Ashtabula.
 

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Could you describe your transfer case build more.

I need a drivers drop transfer case that will bolt up to the 29 spline NV4500 and I am not sure what parts are compatible between the light duty NP241 and NP241DHD (I assume that this is the only 240 series with a 29 spline input. Finally I have to have the fixed output, no room for the factory.

THANKS
 

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Discussion Starter · #17 ·
The only factory cases that fit a 29 spline Dodge NV4500 are the 94 and up DHD and the pre 94 cast iron NP205(right hand drop) with a Cummins and a Getrag 360 trans. The Cummins auto used the DLD and the standard used the DHD, both of which have PTO front cases that are about 1 inch deeper and very specific range planitaries and main shafts, with no fixed output conversions availible that I am aware of. The 29 spline input will fit in the non HD 241's, but you must have a spacer made to adapt the smaller mainshaft pilot bearing into to the larger bore in the DHD input gear. There is two different DHD 29 spline input gears, early and late, 96 model cut off I think. All New Process transfer cases had a mid year change to the pitch of the range planitary gear sets, so be carefull which one you get. I believe this co-insided with the input gear bearing change, from early double ball bearing with plastic cage to the late single row with metal cage. Depending on how much drop you need, you can use a Chevy 241 C cases with a JB conversion fixed output kit , and reposition one of the case to trans bolts. This is the list of parts in my case, with donor vehicle info:
95 Ram Cummins 242 DHD 29 spline input gear with custom bearing sleeve
89 Cherokee XJ 242 AMC front case half with custom dentent system and 32 spline front 1310 cv yoke
94 Suburban 2500 241 C rear case half, chain and sproket set, 6 pinion range planitary, and mode fork
93 Ramcharger 241 D 32 spline main shaft and tail housing(for fixed output) and with reindexed pump alingnment teeth for left hand drop
92 Comance MJ 231 J shift plate and cast aluminum range fork
79 Ford F250 NP205 32 spline rear output yoke for 1330 u joint
This case only contains 3 custom parts, the rest are used factory pieces I had from cores at my shop. One of my wheeling buddies, that watched me build it, calls it Franken-Case. If anyone has any specific questions, or needs any of these parts or even a complete unit of any type, let me know. I own a shop that specializes in transmissions, transfer cases and differentials.
 

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I like the exhaust manifold setup. Is that a cut 6BT or a 4BT manifold?
 

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Discussion Starter · #19 ·
Cut 6BT, 10,000 hard miles with no problems.
 
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