Diesel Conversion Options for Expo Rig

[78ScoutII]

I posted the below thread over on one of the Scout Forums to get more specific swap info. but thought I would post it here to get feedback on parts availability in central and south america. Any suggestions? Thanks!


Hello all, new here to the site and diesels but not IH's. Currently have a 78 Scout II that I drove for years with a 345, 727, D20, D44 w/ 3.73’s during college and love it! Life is a little different now with two small (4 & 5)children and I'm wanting to buy a traveller/terra and turn it into an expedition-style family cruiser, camper, and my DD. This includes eventually driving through central and south America when the kids get older so parts availability is important. Of course my first thought was diesel for its economy, torque, and reliability. I love my 345 but getting 12 mpg on 3,000 mile family overland camping trips just won't work :no:

All that being said I am looking into options for which conversion is best for me from people who know much more about what is involved than me. I would like to reuse as much from my scout II as I can but realize that might not be possible. I do not have a welder or know how to weld and i don't have a large budget for the project but I have time, generally good mechanical skills, and willpower, lol. I am looking for the most straight forward conversion that would achieve the best MPG while providing enough umph to get me around on forest service roads, up decent hills, and some backcountry exploring. The options as I see them are:

1. Cummins 4bt - Would obviously be a great swap but through reading many threads seems as though there is a fair amount of custom fabrication involved which I don't think I have the capacity to do myself or the money to pay someone else to do. LOVE the economy but am also concerned about the NOISE being I will have my family riding with me for extended trips and I can see it getting to everyone after a while in the rig. Approximately the same weight as stock 345 so should be able to keep my D44's. Not sure which transmission to use but seems like there are a few different options. Obviously would be expensive…

2. Cummins 6at - have not heard as much about these conversions but I know there are a few out there. Anyone have some links to detailed threads of the conversion in a scout? On the plus side I would get the reliability and economy of a cummins but I have heard they are much quieter. Is this conversion any more straight forward than the 4bt? (i.e. – less expensive, lol)

3. 6.2 chevy diesel – Seems much less expensive to get, find parts for but doesn’t quite have the economy of the cummins. Seems I can get a wrecked donor truck fairly inexpensively and use the parts from it (radiator, motor, transmission, t-case) since I have a 2” body lift on my current scout. I know there will be some motor mount fabrication but I’d be willing to pay for small fab jobs like that. Would need to go with Hydroboost but that does not seem too complicated. Since a lot of chevy’s were passenger side drop I should be able to use my stock axles.

4. SD33T – Obviously this was my first thought because I could just buy a diesel traveler or terra and not have to do a conversion but the high cost of parts and repairing and the lack of umph to do some backcountry exploring have me worried. Would hate to be in costa rica with the family and the engine crap out on me.

There might be other options out there but there seem to be the most common. I am in the planning stages right now so any help or guidance you can give me would be most appreciated. Thanks!

 

[kickingprop]

You might also check out the 4bd1t and 4bd2t Isuzu motors found in NPR trucks. 3.9L fully rebuildable with basic tools (cylinders are sleeved).

They cant be built to make the kind of power a 4bt can, but they can be built to get you plenty of power and reasonable (20-22mpg in a full size rig) mileage.

The Cummins b3.3t is also a popular swap that will make approx 300ft-lbs and give good fuel economy. The QSB series cummins are computer controlled and supposedly are much better on vibration/noise but I have no first hand experience with them like I do the 4bd Isuzu's

 

[ExpoMike]

I do not have a welder or know how to weld and i don't have a large budget for the project

That quote right there should keep you from attempting a conversion. Even for popular rigs, I really haven't seen a true bolt in that didn't require some fab/welding and/or lots of $$$. No sure about SA but the mileage gain versus the cost difference between gas and diesel, you're likely going to break even on fuel costs. That's won't account for the conversion cost which could take years to see a break even point.

Engine swaps, though not sounding hard to do, even within the same platform (like a Chevy truck, gas to diesel or I-6 to V-8) can be a challenge at times.

Not that you want to hear this but if there is nothing wrong with your current drivetrain, I would leave it as is. That's my honest opinion.

 

[78ScoutII]

Thanks for your replies. kickingprop - I will look into the isuzu motors, they look promising. Expomike - I have a few friends that are experienced welders that I am sure would give me a hand but I just don't want to have to rely on them for rediculously extensive welding work. I guess I should mention that by large budget I mean less then $5,000. If nothing else I would go with the stock scout diesel

 

[kickingprop]

The stock Scout diesel is a good little motor if you can find the turbo version. the NA version is pretty gutless though. It would definitely be the easiest to put into the scout and get on the road for the least amount of money and still give you improved mileage. Just dont expect to win any races with it. :smiley_drive:

EDIT: Another motor to consider seriously... The gas LS(x) series GM motors are bulletproof and will give you good mileage. I put a 5.3/4L60E in my CJ7 and get a steady 21-22mpg on the highway when driven conservatively. These engines are everywhere and the transmission is pretty stout too. I bought an engine/tranny/computer combo for $1100 with only 60k miles on it from a totalled 2001 silverado. I've only got about 10k miles on the swap in my CJ so far but its been flawless!

 

[reece146]

I recently did the diesel math for my XJ. Assuming 10000 km / year (~6200 mi / year) and 14..16 mpg vs 22..28 mpg it came out to ~$700 / year.

More trouble than it's worth IMO unless you have a blown engine to replace...even then...

 

[dragogt]

This http://scoutparts.com/products/?view=product&product_id=16576 should let you do the 6.2 "relatively" easily; Its not a high HP engine but setup right and you can still net low 20's on the highway..


Take a look around http://www.thetruckstop.us/forum/forumdisplay.php?92-6-2-and-6-5-Diesel-Engines for The Best info on the net for them...

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[modernbeat]

I recently did the diesel math for my XJ. Assuming 10000 km / year (~6200 mi / year) and 14..16 mpg vs 22..28 mpg it came out to ~$700 / year.

More trouble than it's worth IMO unless you have a blown engine to replace...even then...

I agree that from a pure financial point it's usually not worth it.

BUT, if you need extended range and don't want to carry additional gas cans (or you are already carrying cans and can't carry even more) then it could be worth it. Or, if you want an engine that can go hundreds of thousands of rough miles without having to be festooned by fragile electronic sensors and wiring, then diesel is the right choice.

 

[1leglance]

If you are purely looking at a diesel just to hit Central/South America then save your money for the trip itself.
Gas is everywhere and cheaper than the US usually, range isn't an issue except in certain areas in South America and you can plan around those.

The trip is what matters, keep the rig rolling as it is so you can enjoy time with the family and put the conversion money into the trip fund.

Now all that said I am doing a 6.2 convserion into my 70 burb as it is as bolt in as you can get, my wife works for a diesel shop, my parts cost are super low and it is a learning project for my 15yr old....and I am still second guesing it all

 

[reece146]

... Another motor to consider seriously... The gas LS(x) series GM motors are bulletproof and will give you good mileage. I put a 5.3/4L60E in my CJ7 and get a steady 21-22mpg on the highway when driven conservatively. These engines are everywhere and the transmission is pretty stout too. I bought an engine/tranny/computer combo for $1100 with only 60k miles on it from a totalled 2001 silverado. I've only got about 10k miles on the swap in my CJ so far but its been flawless!

How was your CJ7 set up? Lift, tires, gearing?

 

[kickingprop]

3.31 gears currently on 4" lift with 33's. I cruise it at 60-65 and dont shift it into drive (e.g. I dont use OD on the 4L60E). This keeps it at around 2100rpm's or so.

That fuel mileage number drops VERY quickly when I start hammering on it though around town to around 14.

 

[78ScoutII]

This http://scoutparts.com/products/?view=product&product_id=16576 should let you do the 6.2 "relatively" easily; Its not a high HP engine but setup right and you can still net low 20's on the highway..


Take a look around http://www.thetruckstop.us/forum/forumdisplay.php?92-6-2-and-6-5-Diesel-Engines for The Best info on the net for them...

Sent from my T-Mobile Galaxy S2 using Tapatalk 2

Thanks for the link. I was leaning toward the 6.2 initially for parts availability and cost.

I recently did the diesel math for my XJ. Assuming 10000 km / year (~6200 mi / year) and 14..16 mpg vs 22..28 mpg it came out to ~$700 / year.

More trouble than it's worth IMO unless you have a blown engine to replace...even then...

Well my 345 is currently at the stage when it needs rebuilt which is why i'm questioning whether or not to convert to diesel

BUT, if you need extended range and don't want to carry additional gas cans (or you are already carrying cans and can't carry even more) then it could be worth it. Or, if you want an engine that can go hundreds of thousands of rough miles without having to be festooned by fragile electronic sensors and wiring, then diesel is the right choice.

Exactly my thinking.

 

[78ScoutII]

Can anyone confirm what kind of diesel is most prevalent in central and south america as far as getting parts?

 

[greengreer]

I second the 6.2 if you are set on diesel, they are not much larger than a smallblock and have the same motor mount and bellhousing pattern. If you are looking to keep your 727 you might run into issues getting it to drive properly, you would need to have the right converter that works with the low rpm torque of a diesel. I am not sure what side the diff is on a scout, but if it's passenger side then look for the whole shebang, the th400 is bulletproof and cheap to get parts for. If you can, get a donor vehicle it's your best bet as you will need te hydroboost too.

 

[dragogt]

I agree that from a pure financial point it's usually not worth it.

BUT, if you need extended range and don't want to carry additional gas cans (or you are already carrying cans and can't carry even more) then it could be worth it. Or, if you want an engine that can go hundreds of thousands of rough miles without having to be festooned by fragile electronic sensors and wiring, then diesel is the right choice.

X2

If you are purely looking at a diesel just to hit Central/South America then save your money for the trip itself.
Gas is everywhere and cheaper than the US usually, range isn't an issue except in certain areas in South America and you can plan around those.

The trip is what matters, keep the rig rolling as it is so you can enjoy time with the family and put the conversion money into the trip fund.

Now all that said I am doing a 6.2 convserion into my 70 burb as it is as bolt in as you can get, my wife works for a diesel shop, my parts cost are super low and it is a learning project for my 15yr old....and I am still second guesing it all

Agreed

Thanks for the link. I was leaning toward the 6.2 initially for parts availability and cost.



Well my 345 is currently at the stage when it needs rebuilt which is why i'm questioning whether or not to convert to diesel



Exactly my thinking.

Sure

I second the 6.2 if you are set on diesel, they are not much larger than a smallblock and have the same motor mount and bellhousing pattern. If you are looking to keep your 727 you might run into issues getting it to drive properly, you would need to have the right converter that works with the low rpm torque of a diesel. I am not sure what side the diff is on a scout, but if it's passenger side then look for the whole shebang, the th400 is bulletproof and cheap to get parts for. If you can, get a donor vehicle it's your best bet as you will need te hydroboost too.

Yep best bet is to ether sell the current rig and then buy one that's diesel, or get a complete doner to rob small parts off..


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