Starting to plan a diesel swap for my 80-series. Input is welcomed!

[Sile]

So now that my '96 80-series is not my daily driver, I'm starting to plan out a diesel swap for it. Its stock 1FZ-FE is still running reasonably strong at 213k miles (leaks a fair bit of oil from various seals, but otherwise ok), so I'm not in a hurry and am planning to spend plenty of time overhauling whatever engine and parts I get before ever tearing the 80 down. Here are my current thoughts, and anyone is welcome to drop some knowledge/experience on the topic.

Engine: Cummins ISB3.9 170hp (newer version of the 4BT), or Isuzu 4BD1T or 4BD2TC

Reasoning:
While my first choice would be a 1HD-T or FT swap, I don't want to spend that much and don't want to deal with the challenge of finding parts down the road. While the simplicity of the mechanical 4BT is nice, I don't want to deal with the noise and vibration, and several people on the forum have noticed that 4BT swaps tend to be sold shortly after completion because the noise and vibration are just too bad.

ISB3.9 Pros: Newer engine, more power, more efficient, electronically controlled but still relatively simple via built-in ECU, common rail injection, rear gear set (reduces vibration), quieter, about 100 lbs lighter than a 4BT.
ISB3.9 Cons: More expensive than mech 4BT (though still far less than a 1HD), little-to-no info regarding 80-series swaps, the rear gear train makes fitment more unknown, and transmission/t-case compatibility questions (see trans section)

4BD1T or 2TC Pros/Cons: No idea yet, as I don't know that much about the engine yet.

Transmission:
This is where things get interesting. My '96 has the A343F transmission with the TCU integrated into the ECU, so I'll either have to shell out for a stand-alone TCU (which I'd rather not do), or change transmissions. The easiest solution from the T-case perspective is to swap to an A440F from a 91-92 80-series, but then there's still the question of the engine-side of the bellhousing. The ISB3.9 comes with either SAE 2 or SAE 3 bellhousing, and is usually mated to an Allison 1000 5 or 6 speed auto.

From what I've read, the Allison 1000 is a fairly solid transmission, that double-overdrive (0.61 6th gear) sure would be nice for highway RPM, and it's already very compatible with the ISB3.9, but I have no idea if it would even fit in the transmission tunnel (even with some hammering) and I'd either need a custom-fabbed t-case adapter, or go to an aftermarket t-case (again, expensive and not sure if there are options).

While I'd like to keep it auto, I'm not totally shutting out the idea of switching to manual if it greatly simplifies things. It looks like it might be possible to adapt an NV4500, but would require custom adapters or machining an SAE #3 bellhousing.

There are a lot of variables to the equation, and I'm going to start calling some shops (Jonesy's Offroad, Advance Adapters, etc.) to get ideas on what they think may be feasible.

 

[FF LC FREAK]

I would hope you have read Wheelingnoob's thread already - https://forum.ih8mud.com/diesel-tec...uzu-4bd1t-lexus-lx450-land-cruiser-build.html. Longbow also has several good write-ups. After everything I've seen on this forum, Isuzu is the way I would go. There is lots of research that has already been done, and you won't have to re-invent the wheel so to speak. After spending a couple of years in the diesel forum, I haven't seen anyone put in the Cummins you are talking about, but there have been several 4BT swaps. But, like I said, Isuzu would be my choice. My $.02.

 

[69rambler]

The ISBE RGT 4BT's are 3.9 and more commonly 4.5 liters. They are not 100 lbs lighter than a mechanical 4BT, they are heavier as they are physically larger. They are quieter than a stock older mechanical 4BT and much smoother as this is the reason for the RGT.

The RGT commonrail engines are quieter and smooth, but are not generally as efficient as a basic VE 4BT. The Commonrail engines shine in NVH and driveability while they get about the same mileage as a VE 6BT and occupy the same space. The 4BT commonrail ECM's are well supported and tunable through the right folks, but not through Cummins and certainly not approved by Cummins.

The RGT engines are a very challenging engine to use in a conversion. Unless you are very experienced with a well equipped shop to make the parts you need I would hesitate to use one.

The 4BD1T/2T engines are pretty nice. Likely the only 1L/cyl 4 banger diesel that a wife would tolerate, possibly enjoy.

Every downside to the Isuzu engines is directly related to their being designed for use in cabover trucks.

Might seem counter intuitive, but electronic autos are more reliable, efficient and consistent compared with hydraulic governed ones. It may seem like a hydraulic governed auto's lack of electronics are appealing and simpler, but they are vastly more complex to make function properly outside their intended use than a pre-programmed ready to run, tunable and self diagnosing aftermarket transmission controller. The cost of the aftermarket controller and harness is almost always less than making a hydraulic auto work so-so.

The Allison 1000/2000 is big. There is a drivetrain efficiency loss associated with their mass and fitting one in an 80 is likely to be a challenge. Certainly a good transmission, but not ideal behind a 4 cylinder diesel in a 6500lb SUV.

Might not hurt to take a look at the 6BT, especially the early, dirt cheap, smooth, fairly quiet, efficient ones if you have little experience with 4 cyl diesels.

Highly likely you'll get an end result you'll love with a 12 valve Cummins in an 80.

 

[Sile]

Thanks for the replies, guys!

FF LC FREAK, I'd gotten part-way through Wheelingnoob's thread, but hadn't finished it yet. The more I'm reading about it, the stronger the 4BD1T looks. I'll also track down Longbow's write-ups.

69rambler, thanks! It looks like I had some mis-information on the RGT 4B, so thanks for clearing that up! I'm not very experienced and don't have a well-equipped shop (the only things I have on my side are time and a willingness to learn), so it sounds like the ISBE is out. I've looked at the 6BT, but I'm concerned with both the size and weight (1100lbs, I think) of the engine, and not sure I want to expose the rest of the drivetrain to that much torque.

 

[69rambler]

Thanks for the replies, guys!

FF LC FREAK, I'd gotten part-way through Wheelingnoob's thread, but hadn't finished it yet. The more I'm reading about it, the stronger the 4BD1T looks. I'll also track down Longbow's write-ups.

69rambler, thanks! It looks like I had some mis-information on the RGT 4B, so thanks for clearing that up! I'm not very experienced and don't have a well-equipped shop (the only things I have on my side are time and a willingness to learn), so it sounds like the ISBE is out. I've looked at the 6BT, but I'm concerned with both the size and weight (1100lbs, I think) of the engine, and not sure I want to expose the rest of the drivetrain to that much torque.

Well, I think the thing to understand is that to put a 240 or so cubic inch diesel in a 6500 pound SUV you will be turning it up to 150 HP and 400 ft/lbs or more to enjoy driving the vehicle.

An early 6BT is 160HP and 400 lb/ft. This kind of mellow diesel power will not harm your drivetrain unless you drive it like you're trying to kill it. The 80 series transmissions, including the A343F you have are good trannies. Something many keyboard diesel conversion pro's fail to realize is how important a role the torque converter plays not just in efficiency, but acting as a fuse to protect the rest of the drivetrain. With the right converter specs and the right compushift tune to control shifting and lockup you can have a nice balance of power, mileage and preventing heavy loading of the engine at low RPM that will damage drivetrain parts. A significant oversight many inexperienced people make is that you want a very low converter stall speed for efficiency. This is not true. 1800-2000 RPM stall speed is ideal and allows 4 cylinder diesels to achieve boost making RPM before loading and keeps idle shakes down. It also allows the transmission to achieve higher line pressure before torque is passed through it.

The Isuzu and 4BT 4 cyl's are about 800-850 lbs. They are about the same size with the 4BT having definite advantages for fitting in tighter places. The Isuzu's are larger engines with everything required on them.

The 6BT weighs about 1050-1100 and fits quite a bit better into an 80 series than a 4 cylinder due to the way it's laid out. The Toyota 1FZ gas engine and 12 valve Cummins are virtually the exact same physical size. Something to consider is that the average 2500 Dodge 4x4 pickup weighs about 5700 lbs with a 5.9 Cummins. The Dodge frame and suspension isn't nearly as well made as the 80 series Toyota stuff.

On a scale of 1-10 in terms of difficulty to achieve a nice finished result doing a diesel conversion into an 80 series I would put a 12 Valve Cummins at a 4 or 5 and an Isuzu at an 8 or 9. In addition the 6BT route will cost thousands less and still achieve around 20 MPG.

A note on 4 cyl diesels- 4BT/4BD1T/2T will achieve great mileage when they are in proper working order, tuned and installed correctly. However, many lack experience with these engines and do not know what parts work and which ones are terrible. Lots of bad info out there. People running big turbos, gearing them wrong and very often people have no reference to know what the engine should actually run like. Most pro shops have no clue how to assess or tune these engines. I've personally seen it from some of the biggest names in the diesel performance business. They might be able to make big power, but they can't tell when a mild engine converter stall speed is wrong or a timing advance isn't working on a 4BT. The 6BT route removes all of these unknowns. Any shop can work on them, you know what it's going to sound and run like when it's finished.

Food for thought. The Isuzu's are fine engines, but there is a lot to figure out and fabricate to make them work in an 80 series. The Cummins stuff is pretty much chiseled in stone now. From a time perspective I would put a complete Isuzu install around 200 hours and a 6BT Cummins install around 30 hours.

Everyone's idea of "nice finished result" varies, but what I mean is everything looking and functioning like it was made that way. AC works, cruise works, gauges work, etc.

 

[overpaid slacker]

Hey 69rambler,

many thanks for your posting. Your information and expertise is amazing. I am trying to absorb this info as much as possible in order to get my 4bt (ve pumped) 76 fj40 built correctly. Please keep posting!

 

[Wheelingnoob]

Thanks for the replies, guys!

FF LC FREAK, I'd gotten part-way through Wheelingnoob's thread, but hadn't finished it yet. The more I'm reading about it, the stronger the 4BD1T looks. I'll also track down Longbow's write-ups.

My thread is not complete yet, still have not started actually putting the engine into the truck. I am hoping to start that around the end of September. So far everything is going smoothly and I do not see any big road blocks ahead. The swap when complete will retain A/C, Cruise and everything thing else available in the truck stock just with a Diesel heart.

The 6BT looks like a good option with the kit that is soon to be available. For myself the last thing I wanted to do was add more weight to the truck. Already have full bumpers front and back, M12000, soon to have drawers, sliders, Aux fuel tank, Roof rack and RTT plus our gear for 1-2 weeks of remote camping so its going to be a heavy beast.

I'll keep my thread going so you and others can follow along, so far its been a very easy motor to work with.

 

[Sile]

The 6BT weighs about 1050-1100 and fits quite a bit better into an 80 series than a 4 cylinder due to the way it's laid out. The Toyota 1FZ gas engine and 12 valve Cummins are virtually the exact same physical size. Something to consider is that the average 2500 Dodge 4x4 pickup weighs about 5700 lbs with a 5.9 Cummins. The Dodge frame and suspension isn't nearly as well made as the 80 series Toyota stuff.

What's got me concerned is that the front of my 80 is already heavy with my Slee Shortbus and Warn 9.5 hanging off the front, and I haven't even done a dual-battery setup yet (plus a few other things that will add some weight). I'm not worried about the frame supporting that much weight, but with how the weight affects crawling. The Dodge 2500's used the 5.9 Cummins, but that was designed around high towing capacity (which I won't be doing), not around rock crawling and muddy off-roading (which I will be doing). When it comes to ledges, an extra 300 pounds over the front axle can make the difference between being able to crawl up ledges and having to bump your way up them. I checked out Jonesy's "Predator" 6BT build, and the thing is loud as hell and had trouble making it through stuff that my 80 will currently waltz through (granted, their tire selection may have contributed).

I don't doubt the quality of the 6BT and the ease of swap. I just don't think it's the right choice for a vehicle that I take on long trips to go wheel the hell out of it. It's definitely a trail rig, not an expedition rig.

 

[Wheelingnoob]

Any older mechanical diesel will make more noise than a newer common rail diesel. It all comes down to how much noise you can handle, the 4BT is about as noisy as you can get in the 4cyl diesels. The 4BD1T I am going be running will be quieter but still nothing like the stock Gas motor, hell there are times I cant even tell my 1FZ is running. Best advice is to hear each of the engines you are planing on running in person before making a choice. Video and recordings are a poor representation of over all noise an engine makes.

 

[Slowerthanu]

What's got me concerned is that the front of my 80 is already heavy with my Slee Shortbus and Warn 9.5 hanging off the front, and I haven't even done a dual-battery setup yet (plus a few other things that will add some weight). I'm not worried about the frame supporting that much weight, but with how the weight affects crawling. The Dodge 2500's used the 5.9 Cummins, but that was designed around high towing capacity (which I won't be doing), not around rock crawling and muddy off-roading (which I will be doing). When it comes to ledges, an extra 300 pounds over the front axle can make the difference between being able to crawl up ledges and having to bump your way up them. I checked out Jonesy's "Predator" 6BT build, and the thing is loud as hell and had trouble making it through stuff that my 80 will currently waltz through (granted, their tire selection may have contributed).

I don't doubt the quality of the 6BT and the ease of swap. I just don't think it's the right choice for a vehicle that I take on long trips to go wheel the hell out of it. It's definitely a trail rig, not an expedition rig.

Dodge made the Cummins fit a very old frame design. It was a race to get the best diesel on the market. Chrysler did this to actually sell trucks, since nobody really wanted an already 20 year old design, slap one of the best known big rig engine makers name on the side and boom, instant classic.

200 pounds is minimal in an already 6000 pound vehicle, you are talking maybe a 4% gain in overall weight on the vehicle. Mentally, you may think it makes a difference but lets be honest, the 80 series is an excellent 4x4, but it wasn't designed to rock crawl.

Honestly, I would push you towards a 6bt. You could pickup a used 4x2 W250 with a couple hundred thousand miles for $2000 and have every part needed. Then, you could sell the transmission and transfer case and come out even in the end after scrapping the rest. Talk about parts being cheap and plentiful. You now have the ability to get parts from a Cummins dealer or a Dodge dealer.

 

[Sile]

Agreed on the videos. I've heard 4BTs and 6BTs in person, so now I'm just trying to find a running 3.9 Isuzu NPR to listen to.

 

[doug720]

Where are you located? I have an Isuzu in a 60 to check out if you're near LA.

My 4BD2Tc has been a great engine for us. I think it was an easy swap, fits well, quiet, pulls well, has power steering and AC and it gets and around 20 mpg loaded with a roof rack!

I did my swap in about 3 weeks of nights of weekends, and for basically free when I sold off my old and left over parts. In fact I bought another 4BD2 a couple of months ago for $300 and found a set of factory Isuzu piston kits for $400. Deals are out there for either a Cummins or an Isuzu.

Last week I met a guy who had a 4BT Cummings in a Bronco, but was going to pull it out due to noise and vibration! His family refused to ride in the thing. DAnimal here on mud told me about the noise and vibration with a 4BT when I was looking for diesel options/ He recommended against using the 4BT.

I have a pair of 6BT's in my boat. Great engine, but loud and they vibrate. In a LandCruiser, I would look elsewhere for a more civilized option.

My $2.00 worth...

Doug

 

[Sile]

Thanks for the reply, Doug! I'm in San Antonio, so that'd be a bit of a drive. Thanks for the offer though! How much trickery was required to mount the 4BD up to the H55?

 

[OGBeno]

Well, I think the thing to understand is that to put a 240 or so cubic inch diesel in a 6500 pound SUV you will be turning it up to 150 HP and 400 ft/lbs or more to enjoy driving the vehicle.

An early 6BT is 160HP and 400 lb/ft. This kind of mellow diesel power will not harm your drivetrain unless you drive it like you're trying to kill it. The 80 series transmissions, including the A343F you have are good trannies. Something many keyboard diesel conversion pro's fail to realize is how important a role the torque converter plays not just in efficiency, but acting as a fuse to protect the rest of the drivetrain. With the right converter specs and the right compushift tune to control shifting and lockup you can have a nice balance of power, mileage and preventing heavy loading of the engine at low RPM that will damage drivetrain parts. A significant oversight many inexperienced people make is that you want a very low converter stall speed for efficiency. This is not true. 1800-2000 RPM stall speed is ideal and allows 4 cylinder diesels to achieve boost making RPM before loading and keeps idle shakes down. It also allows the transmission to achieve higher line pressure before torque is passed through it.

The Isuzu and 4BT 4 cyl's are about 800-850 lbs. They are about the same size with the 4BT having definite advantages for fitting in tighter places. The Isuzu's are larger engines with everything required on them.

The 6BT weighs about 1050-1100 and fits quite a bit better into an 80 series than a 4 cylinder due to the way it's laid out. The Toyota 1FZ gas engine and 12 valve Cummins are virtually the exact same physical size. Something to consider is that the average 2500 Dodge 4x4 pickup weighs about 5700 lbs with a 5.9 Cummins. The Dodge frame and suspension isn't nearly as well made as the 80 series Toyota stuff.

On a scale of 1-10 in terms of difficulty to achieve a nice finished result doing a diesel conversion into an 80 series I would put a 12 Valve Cummins at a 4 or 5 and an Isuzu at an 8 or 9. In addition the 6BT route will cost thousands less and still achieve around 20 MPG.

A note on 4 cyl diesels- 4BT/4BD1T/2T will achieve great mileage when they are in proper working order, tuned and installed correctly. However, many lack experience with these engines and do not know what parts work and which ones are terrible. Lots of bad info out there. People running big turbos, gearing them wrong and very often people have no reference to know what the engine should actually run like. Most pro shops have no clue how to assess or tune these engines. I've personally seen it from some of the biggest names in the diesel performance business. They might be able to make big power, but they can't tell when a mild engine converter stall speed is wrong or a timing advance isn't working on a 4BT. The 6BT route removes all of these unknowns. Any shop can work on them, you know what it's going to sound and run like when it's finished.

Food for thought. The Isuzu's are fine engines, but there is a lot to figure out and fabricate to make them work in an 80 series. The Cummins stuff is pretty much chiseled in stone now. From a time perspective I would put a complete Isuzu install around 200 hours and a 6BT Cummins install around 30 hours.

Everyone's idea of "nice finished result" varies, but what I mean is everything looking and functioning like it was made that way. AC works, cruise works, gauges work, etc.

Very nicely written and put.

 

[american psycho]

Simple

Just buy one that has the diesel in it you cannot afford, unless you're really into working on cars.

Link to European Autoscout

 

[69rambler]

What's got me concerned is that the front of my 80 is already heavy with my Slee Shortbus and Warn 9.5 hanging off the front, and I haven't even done a dual-battery setup yet (plus a few other things that will add some weight). I'm not worried about the frame supporting that much weight, but with how the weight affects crawling. The Dodge 2500's used the 5.9 Cummins, but that was designed around high towing capacity (which I won't be doing), not around rock crawling and muddy off-roading (which I will be doing). When it comes to ledges, an extra 300 pounds over the front axle can make the difference between being able to crawl up ledges and having to bump your way up them. I checked out Jonesy's "Predator" 6BT build, and the thing is loud as hell and had trouble making it through stuff that my 80 will currently waltz through (granted, their tire selection may have contributed).

I don't doubt the quality of the 6BT and the ease of swap. I just don't think it's the right choice for a vehicle that I take on long trips to go wheel the hell out of it. It's definitely a trail rig, not an expedition rig.

The "predator" is actually surprisingly quiet at idle in person and the exhaust is wide open, right off the turbo. It is quieter and smoother than any 4BD Isuzu. Maybe it doesn't come through in the videos, but I can assure you the predator is not obnoxious in sound or manners, just looks. My shop truck has the exact same 1993 Dodge engine in it as the predator and is reasonably quiet, very smooth and has great power and economy with 306,000 miles on it.

It's worth noting that there are several different flavors of 6BT's. The different versions all have different noise levels. The 2003+ commonrail engines are pretty quiet followed by the 89-93 engines which have a nice mellow idle sound to them. The 94-98's are a bit louder stock, but most of these have their base timing cranked because they are fixed time motors and they really clack at idle with 15+ degrees. The 98-02 24 valve motors are by far the loudest. If you associate Cummins with loud the 98-02 engines are likely the reason why.

I don't think the added weight has any detrimental effects on handling. I actually think the 4BT and Isuzu 80's I've done using non-Toyota transmissions that sat the engines forward from stock handled a lot worse than stock whereas the 6BT installed with the mass in the same location as the 1FZ handles the same as it did with the 1FZ.

The 6BT had nothing to do with the Predator not being able to make it up a slick grass covered hill.

 

[69rambler]

Where are you located? I have an Isuzu in a 60 to check out if you're near LA.

My 4BD2Tc has been a great engine for us. I think it was an easy swap, fits well, quiet, pulls well, has power steering and AC and it gets and around 20 mpg loaded with a roof rack!

I did my swap in about 3 weeks of nights of weekends, and for basically free when I sold off my old and left over parts. In fact I bought another 4BD2 a couple of months ago for $300 and found a set of factory Isuzu piston kits for $400. Deals are out there for either a Cummins or an Isuzu.

Last week I met a guy who had a 4BT Cummings in a Bronco, but was going to pull it out due to noise and vibration! His family refused to ride in the thing. DAnimal here on mud told me about the noise and vibration with a 4BT when I was looking for diesel options/ He recommended against using the 4BT.

I have a pair of 6BT's in my boat. Great engine, but loud and they vibrate. In a LandCruiser, I would look elsewhere for a more civilized option.

My $2.00 worth...

Doug

80 series is total different ballgame from a 60.

Also, marine 330/370 Cummins engines have around 15.3:1 compression, fixed timing with significant advance to make the reliable power they do. I have plenty of experience decompressing Cummins motors with marine pistons and outside of extreme performance there's only drawbacks. The lower the compression, the louder the combustion.

Something else to keep in mind is that Dodge engines have double wall tin and other sound deadening panels built in. Industrial engines including all 4BT's do not.

Lower compression, more timing advance and higher injection pressure make diesels louder. Higher compression, conservative timing and lower injection pressures quiet them down.

 

[doug720]

My marine 5.9's are 250 HP models - 6BTA5.9M models and they are very rough idling and loud compared to my Isuzu, or even my 7.3 Ford.

I like the Cummins and don't know anything about 80 Series LC's, but I found the Izuzu a good option for my 60.

Doug

 

[69rambler]

My marine 5.9's are 250 HP models - 6BTA5.9M models and they are very rough idling and loud compared to my Isuzu, or even my 7.3 Ford.

I like the Cummins and don't know anything about 80 Series LC's, but I found the Izuzu a good option for my 60.

Doug

Wouldn't a comparison to a 5.9 from a Dodge be a little more reality here?

 

[PhrogsPhorever]

If you get up to Austin ever, look up Davegonz, he should still have my '94 80 with a 4BTA.

4BT is LOUD but it was a great motor.

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