Ideal Diesel

For everything related to converting and up keeping diesel engines in an FSJ

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Chivin_Jeeper
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Ideal Diesel

Post by Chivin_Jeeper »

What would you consider to be the ideal diesel for a 79 Chief? Cummins 4BT? Cummins 6BT? I'm wanting to convert soon, but need ideas on what works and what doesn't.


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Pablo
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Re: Ideal Diesel

Post by Pablo »

What are you hoping to achieve? What are your intended uses for the vehicle?
  • 64 FSJ Wagoneer, under the knife
  • 67 FSJ Wagoneer, peacefully taking a break
  • 94 XJ, long-armed on 33's. Bolt on ghetto fab fantastic
  • 16 BU, wife's snow commuter
Formerly: 06 KJ CRD (Constantly Repair Diesel)
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Gumby
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Re: Ideal Diesel

Post by Gumby »

Just do the 6bt cost would possibly be the same between the two.
1984 GW 360/727/208.... 4"/ 31"
2004 CRD QC SRW 3500 4X4 (DD)
1983 "project Dubya" (long term)
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Tatsadasayago
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Re: Ideal Diesel

Post by Tatsadasayago »

A friend did the 6BT, NV4500 and Dana 300 conversion on his Chief.
I drove it on the highway as well as off road and frankly I felt there was too much weight up front that caused the Cherokee to develop some bad wheeling manners when it mattered most.
The other issue it had was too much low end torque. He twisted several drive shafts, blew up drive axle U-Joints and twisted a rear axle shaft off at the flange. Yeah, most of that was due to the driver being too aggressive with the throttle but overall, the running gear just wasn't up to the task.

One of our members here did the swap in a way I thought was pretty smart. He put the FSJ body on a shortened Dodge Ram.
1977 Cherokee Chief - The Blair Jeep Project III
A collection of parts flying in close formation
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REDONE
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Re: Ideal Diesel

Post by REDONE »

Tatsadasayago wrote:
One of our members here did the swap in a way I thought was pretty smart. He put the FSJ body on a shortened Dodge Ram.
Yeah, I can't remember his name or screen name but I'm pretty sure he's in Spokane, the maroon J-truck with the Willy's Overland tailgate. Super clean restomod!

Personally I don't think there is an "ideal diesel" for FSJs, mainly because I don't believe diesel is a superior engine when all things are considered. I can remember seeing gas <$2 a gallon while diesel was still >$4, diesel doesn't burn "cleaner because you get more mpg", diesel still produces way more particulate and ozone, it's just exempt from those restrictions (because commerce relies on diesel). Parts to repair a diesel are so much more expensive that any savings in fuel would constantly be offset. The only metric where diesel is superior is in torque, and if that's what you desire then everything else in an FSJ needs upgraded to both handle it, and utilize it. :|
79 J-10 (Honcho Mucho) KE0LSU
304/Performance Fuel Injection TBI/MTA1/SP2P/Magnum rockers
T18/D20/D44s&4.10s/33" Mud Claws
Grizzly Locker Rear
4" front spring drop, 5" rear shackle flip
Chevy style HEI (ECM controlled)
Dolphin "Shark" gauges in a fancy homemade oak bezel
3/4 resto, rotting faster than I've been fixing it.
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eggman918
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Re: Ideal Diesel

Post by eggman918 »

Turbo diesels are also most efficient at max load/torque so you will see the greatest benefits with a engine that is sized to the rig and tasks it will be doing, the 4BT in my F-250 is just enough tuned where it is to do the job and loaded at highway speeds it's duty cycle is more on par with the marine 4BT in that it will see 25 psi/1,100* EGT's for hours on end and it's under those conditions where i get close to my best mileage and the engine seems to be running it's best it will get 18 mpg there and if I just cruise it will get over 20 the 390 it replaced would get only half that on it's best day.
I can't think of any reason for a 6BT in a FSJ.....but that is just me. A properly tuned 4BT would be fine for a heavier FSJ for a tow pig/trail rig but its still gonna be nose heavy figure 200# + over the V8 and the rig will need to be taller as the 4BT is about the same length as the V8 but is as tall or taller than it is long the 4 is also hard on drive trains it's torque comes on from idle starting at over 200 ft/lbs add to that that there is only 2 power pulses per revolution they will eat transmissions that will hold up to more torque behind other engines. 4BT's are also getting damn price and their quality is going down. The M/B diesels have some promise but for the power levels you will probably want/need the om617 won't do but depending on how much electronics you are tolerant of there are options left but I don't know the details.The VW 1.9 4 cyls can produce power levels comparable to the factory V8's below 5,000' and with compounds get close above that and tou will be loosing close to 500# off the front end and can still be mechanical the 3.0 V6's can make more than enough power for a FSJ but there you are back to electronics the CRD Jeep diesels might work but I can't speak to them ,the last option would be a Cummins factory re power with the new 5.0 CRD V8.................if money is no obstacle ;) that and a close ratio 6 speed would be sweet $25,000 and year or so you would be in good shape.
1967 Wagoneer soon to be TDI powered
1968 F-250 CrewCab Cummins 4BT, ZF-5, NP 203/205,TruTrac's front/rear.
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eggman918
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Re: Ideal Diesel

Post by eggman918 »

Once you decide on if you really want to undertake this and on what engine you need/want I've had good luck with auctions like http://www.copart.com/ for later model stuff if you have the room and time to part out what you wont use can really help with total cash out of pocket.
Late model F350's will often sell for less than a good D-60 front goes for with LOT'S of other desirable parts to sell........IF you want to spend the time I did ti more than once on my last build and have done it on the current build.......$.02
1967 Wagoneer soon to be TDI powered
1968 F-250 CrewCab Cummins 4BT, ZF-5, NP 203/205,TruTrac's front/rear.

Nikkormat
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Re: Ideal Diesel

Post by Nikkormat »

If all you want is torque swap in an IH 392.
Gabe, "reformed" Jeep hoarder.
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eggman918
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Re: Ideal Diesel

Post by eggman918 »

I have contemplated a EFI 300 Ford I-6 with a waste gated turbo sized to make ~6psi from idle up that should produce as much torque down low as any diesel near its weight and be very reliable with good fuel consumption
1967 Wagoneer soon to be TDI powered
1968 F-250 CrewCab Cummins 4BT, ZF-5, NP 203/205,TruTrac's front/rear.

Topic author
Chivin_Jeeper
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Re: Ideal Diesel

Post by Chivin_Jeeper »

Plans will be to restore for shows. Occasional light wheeling but nothing too extreme.


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Topic author
Chivin_Jeeper
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Re: Ideal Diesel

Post by Chivin_Jeeper »

So I see some saying it would just be better to rebuild the 360 rather than do a diesel swap?


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Pablo
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Re: Ideal Diesel

Post by Pablo »

If you are looking to do a classic restoration, then obviously keeping the original engine would be the thing to do. If you are resto-modding it, then you could choose to take many different paths. You could keep the motor entirely stock, put throttle body fuel injection and other mods on it, or swap it out entirely.

With a diesel, you are trading higher upfront costs for potential lower operating costs. It depends on the motor and the use case as to if those lower costs will occur and get you further ahead in the long run. The more miles you go, the more you tow and pull heavy loads-- the greater the chance the diesel will come out ahead.

Given your use case, I would keep it stock or lean to a Vortex/LS swap. It is cheaper and easier to get done and since you are only driving it on occasion, you will not recoup any fuel savings from going to a diesel.

If you are thinking of doing a new high dollar diesel crate motor swap anyway, I would go with the new Cummins over the pasta Dodge motor. The Italian VM motors are not the best built (I had one in a Jeep CRD, and it was garbage throughout).
  • 64 FSJ Wagoneer, under the knife
  • 67 FSJ Wagoneer, peacefully taking a break
  • 94 XJ, long-armed on 33's. Bolt on ghetto fab fantastic
  • 16 BU, wife's snow commuter
Formerly: 06 KJ CRD (Constantly Repair Diesel)

Topic author
Chivin_Jeeper
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Re: Ideal Diesel

Post by Chivin_Jeeper »

While I would love a classic resto, I just don't see the need. Yes, I'll use it for shows, but also a camping vehicle. So I'm adding on board air, water and a switch for the rear window in the back to make it easier at night when I inflate the mattress.


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HeavyMetalThunder_81
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Re: Ideal Diesel

Post by HeavyMetalThunder_81 »

I'd go with the Cummins 4BT swap over the Cummins 5.9. It may be a little more pricey but it is an ideal weight, plenty of power but not too much power, fits a lot nicer, and is a heck of a lot more reliable and lighter than a GM 6.2/6.5 or Ford/Navistar 7.3
-Jonny B.
1979 Cherokee Golden Eagle - UNDER CONSTRUCTION
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AMC 401 - Pro-FLo 4 FI
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R M23 - 4.10, Detroit Locker

1979 Cherokee Chief - Parts
1979 Cherokee Chief - Parts
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janssen
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Re: Ideal Diesel

Post by janssen »

Well I have a 1990 wag 4bt/nv4500/np229/373's/31x10.5 as my DD and Love it. I picked up the jeep already converted - but still needed some fine tuning. I think if I was to do it I would go with the 6bt for a few reasons.

-Towing at highway speeds (120-130 km/hr for me)with the 4bt is something you just dream of but at 90-100 km/hr you can pull a train.
-6bt isn't that much heavier 782 vs 1200lbs approx YMMV etc...
-6bt much cheaper/easier to find
=6bt fits.
-6bt would crush the d44 over time though

I want the old bt series as I run W85

I should be getting more out of my 4bt - mostly stock with a BW171270 turbo.
1990 Wag, cummins 4bt, nv4500. 4"BDS on front - frankenstein rear.
1982 CJ7 SOA, 3/4 Eliptical, 35", T18, Detroit Locked F/R
-next major project - Snorkel for wag - cause diesels can Swim :)

Adventure_Wagon88
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Re: Ideal Diesel

Post by Adventure_Wagon88 »

janssen wrote:Well I have a 1990 wag 4bt/nv4500/np229/373's/31x10.5 as my DD and Love it. I picked up the jeep already converted - but still needed some fine tuning. I think if I was to do it I would go with the 6bt for a few reasons.

-Towing at highway speeds (120-130 km/hr for me)with the 4bt is something you just dream of but at 90-100 km/hr you can pull a train.
-6bt isn't that much heavier 782 vs 1200lbs approx YMMV etc...
-6bt much cheaper/easier to find
=6bt fits.
-6bt would crush the d44 over time though

I want the old bt series as I run W85

I should be getting more out of my 4bt - mostly stock with a BW171270 turbo.
That's an awesome setup! I can't imagine doing the 6BT and attempting to keep stock D44s. That can't be an option! 782 lbs just sounds so much more reasonable than 1200+ for a 6BT. Is your 4BT running an intercooler? I believe I have yet to see a 6BT setup with an intercooler, just seems like there isn't room! What kind of loads do you tow with yours? I am weighing the pros and cons between an 4BT and 6BT swap, and while it seems cheaper to just get a donor truck with 6BT, I don't like the idea of that much weight, and shoe horning that much engine into the compartment of my 88. I also don't have any specific thing I need to tow (yet) but eventually there will be a camper which I would like to get something decent sized, so over 6500 lbs most likely. Is that out of 4BT territory and into 6BT territory? Are you realistically ever going to be able to tow 7000lb and larger loads with a 110" wheelbase truck that was factory rated at around 5000lbs towing?
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tedlovesjeeps71
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Re: Ideal Diesel

Post by tedlovesjeeps71 »

400+ lbs IS a big difference. Can't see why you can't use the "extra space" of the debt to add an intercooler. Tweak the injection pump some and wake it up.

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eggman918
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Re: Ideal Diesel

Post by eggman918 »

I tow with mine and am happy with it's performance truck is 8K and my little trailer is 4K but I have towed as much as 8K and at that weight it's not fast but will pull the grades on the interstate at 55/60 in direct plenty fast for a CGVW of 16K#, with the 4K trailer it'll pull the grades in OD at 65...$.02
1967 Wagoneer soon to be TDI powered
1968 F-250 CrewCab Cummins 4BT, ZF-5, NP 203/205,TruTrac's front/rear.

Adventure_Wagon88
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Re: Ideal Diesel

Post by Adventure_Wagon88 »

Yeah 400 lbs is a huge difference. It's almost like adding a SBC on top of the 4BT actually! I realize it has the added benefit of lots more torque and HP to make up for that weight which is why it seems like not a big deal but realistically it is adding weight exactly where you don't want it. Adding 400 lbs wherever you wanted wouldn't really matter but in the engine compartment it's not a good thing. On paper I think the 6 makes sense. Get a donor Ram (some around me I have seen as low as $2500 for a rough one that runs), beef up the suspension and reinforce the frame some, throw in some 1 ton axles which you were probably doing anyway, and you've got a solid truck. But it's that weight that kills it. And for me, I think i'd rather have an intercooler and electro mechanical fan with more room to work, for my purposes than 2 extra cylinders.

Thanks for the info eggman, that info is most helpful!

Oilburner
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Re: Ideal Diesel

Post by Oilburner »

I am still in the parts-collecting phase, but I will be running an ISB170, that is the common rail version of the 4BT (170HP + 420lbft) + ZF6 + Dana20. Tricky install, with modified adapters everywhere but it should make a fine expedition/camper tow rig. I will start a build thread but it will be in the spring before I have everything ready-

PS: I have a DD 4bt Scrambler w/ a 5spd that I built, it works great but I would not want to listen to it over a 1,200 mile trip :fsj:
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