Efficient 4WD Jeep

[Taylor95]

Are diesel swaps still a good idea? Will diesel still be relevant in 30 years?

I've wanted a Jeep Comanche for a really long time. I found this article today:
https://www.dieselworldmag.com/featu...jeep-comanche/
A guy swapped a 3.9 Cummins engine into a Comanche. The build included a 4.5" lift and 33" tires. He recorded an all time low of 24 mpg, and a high of 36 mpg. Would it be within reason to get 40 mpg or more with this engine? I think that is reasonable if you drive like an ecomodder and perhaps built the truck with fuel economy in mind. Like putting in a NV3500 transmission in lieu of the NV 4500, using a tonneau, etc...

The fuel savings from this setup would make the cost of the build and the time invested well worth it. With the current cost of diesel fuel, it would just about halve my yearly fuel cost. edit: Not to mention having an awesome custom off road vehicle with great fuel economy.

[slowmover]

If you aren’t making an income BECAUSE of 4WD (unlikely, we built the entire country without it) its a mistake.

I get it about wanting “both” drab commuter and exciting weekend toy.

Go back to basics.

1). How long will you keep it?
2). How many miles will it accumulate?
3). As it will eventually be the same out-of-pocket as a three year old vehicle (accepting unreliable transportation is a non-starter. Entire vehicle must be COMPLETELY re-Wired. This is not optional. This is before the complications of a drivetrain swap), what is the annual cost of the latter per AAA or Edmunds “True Cost of Ownership” expressed as cents-per-mile over X period.

4). What will be the additional costs? Offroad is especially high maintenance.

5). The cost of fuel is half or less of a brand-new vehicle at 5-years and 60k miles. Purchase, depreciation, finance, etc, all add up hard.

Go find the three year old nice JK and run TRUE NUMBERS.

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[oldtamiyaphile]

https://www.youtube.com/watch?v=zZmzGYANZvI

Eco off roading.

[Taylor95]

Originally Posted by slowmover

If you aren’t making an income BECAUSE of 4WD (unlikely, we built the entire country without it) its a mistake.

I get it about wanting “both” drab commuter and exciting weekend toy.

Go back to basics.

1). How long will you keep it?
2). How many miles will it accumulate?
3). As it will eventually be the same out-of-pocket as a three year old vehicle (accepting unreliable transportation is a non-starter. Entire vehicle must be COMPLETELY re-Wired. This is not optional. This is before the complications of a drivetrain swap), what is the annual cost of the latter per AAA or Edmunds “True Cost of Ownership” expressed as cents-per-mile over X period.

4). What will be the additional costs? Offroad is especially high maintenance.

5). The cost of fuel is half or less of a brand-new vehicle at 5-years and 60k miles. Purchase, depreciation, finance, etc, all add up hard.

Go find the three year old nice JK and run TRUE NUMBERS.

.

It's not just about the money, but I get your point. Those are all good things to consider before undertaking such a project. It is also about the thrill about creating something unique. A vehicle that is not only capable but economic too.

Off road vehicles cost about the same to maintain as a regular car, with the exception of much faster tire wear. If it is a budget build then it will be more expensive as stuff will break all the time.

At 60k miles the fuel costs in a JK would be about 9k or so. Depreciation really hits hard.

The cost of my build would not be that much in relative terms. It would vary a lot based on where I would source parts from. A crate engine is as cheap as 3k. I could get the truck itself for as cheap as $500. Other mods would likely be around 4k-6k. So I would need to drive around 120k miles to recoup the cost of the build in fuel savings, which is probably unlikely to happen. But it isn't just about that

That video is pretty great, haha.

edit: Now that I think about it, the cost of other mods would probably be closer to 6k to 8k.

[slowmover]

Regular road vehicles don’t have transfer cases or all the changes from the 2WD version first, second, the differences between on and off road vehicles of any sort. It’s a weight penalty, an aero penalty, and a mechanical/electrical penalty. Plus shorter life before replacement or overhaul.

Sure, it could use less fuel. But it won’t ever use less money or even the same. The penalties are inherent.

So come up with the numbers. Against a three year old sedan of some sort. It’s one thing to dive in. But how deep is this pool (my pockets) versus an alternative?

The reliability or lack thereof which threatens my income right down to how do I get to work today — not just other goals scaled back or foregone for what is pleasure-seeking — warrants a plan. An inventory.

There’s the teenager within us trying to persuade Dad. And there is the man who’s supposed to be husband & father who we are or will be. Protector & Provider versus Pleasure Seeker.

Spending money to save money is harder than it looks.

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[Taylor95]

I like that you're making me give a thorough rundown of the cost of this project, rather than an estimate. I will provide the actual cost of things I expect to buy for this project to get an accurate estimate.

1988 Jeep Comanche 4.0L 4wd - $2k
Could be talked down to $1400 due to condition and mileage
-500 from selling the engine, transmission, and transfer case
Net cost: $900

2003 Volkswagen TDI - $2k
(This was cheaper than any sources of a 3.9l cummins engine I could find)

NV3500 - $57 from Pick n Pull on a half day

Wiring harness- can be used from the volkswagen

NP241 transfer case- $144 ebay

Custom driveshafts- ~$600

Front and rear air lockers $1700

Air compressor: $300

Tires and wheels: $1100

4.5" lift kit: $500

Steel for custom rockers: $400

Skidplates: ~$500

That comes out to ~$8200. I would expect to spend at least another $1000 for mating the engine to the transmission, and other things depending on the condition of the engine. So $10k would be a better ball park estimate.

A comparable 3 year old vehicle would be the 2016 Toyota Tacoma or Jeep Wrangler. Those are currently selling for around 30k. A basic 3 year old sedan is around 9-12k right now.

If done correctly, this can be a reliable vehicle. Diesel engines can last a very long time. If I hypermile the truck, it can probably get better mpg than the 10k Corolla. Other Jeep owners report getting an average mpg in the 30-range.

TLDR:
Will it save money? Not compared to buying a sedan, but the fuel cost will be about half of what driving a gasoline Jeep is.

Will it be cool? Yes it will

I would like to add that this would end up being the 3rd-- or even 4th vehicle in my household by the time I am finished. So reliability isn't exactly the greatest concern, though I do expect it to be reliable.

[slowmover]

I’d still add a couple thousand for miscellaneous and the unexpected.

That it’s not primary transportation changes things. If I missed that earlier, sorry.

I’d still recommend the use of a CPM calculator. AAA or EDMUNDS (True Cost of Oenership) as multiple vehicles figure just as much to family budget.

Perspective.

[Taylor95]

Originally Posted by slowmover

I’d still add a couple thousand for miscellaneous and the unexpected.

That it’s not primary transportation changes things. If I missed that earlier, sorry.

I’d still recommend the use of a CPM calculator. AAA or EDMUNDS (True Cost of Oenership) as multiple vehicles figure just as much to family budget.

Perspective.

I think it would be foolish to have a vehicle like what I'm describing to be my only mode of transportation.

I'll check out that calculator. It would give a good perspective on my vehicle cost

[slowmover]

Originally Posted by Taylor95

I think it would be foolish to have a vehicle like what I'm describing to be my only mode of transportation.

I'll check out that calculator. It would give a good perspective on my vehicle cost

Oh, I understand why men want to do it. I just was angling for perspective.

A CPM calculator is a basic business tool. You’ll REALLY like how it sharpens focus. Each pony, then the herd as a whole. Take solace that it’s nearly always more than we expect when extrapolated over a lifetime (major phases thereof).

I zeroed out the full expense of my pickup as a business vehicle (whew, plan worked) as otherwise something this expensive (to buy and to own) would have been foolish. The plan to make the most of it was centered on low fuel cost per mile (diesel was still cheaper per gallon then; tremendous energetic content per gallon advantage) coupled to business use. Squeaked by on that last part. Today I would NOT buy diesel. That window shut.

It’s been a long-tenure faithful servant. But still expensive as 1T pickups are greatly oversized for the majority of use, thus no repairs of consequence are cheap. (A new set of injectors will likely run $5k after pro installation; etc).

As book value declined $3k in 12-years from what I paid, it still makes sense to keep.

It’s the long-term CPM based on actual figures which keeps emotions at bay. Even at 19-mpg overall average annual MPG. (A gasser from a few years before with similar capacity for work would average 8-mpg. The diesel only really shines past 200k with the delay of engine replacement ).

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[hayden55]

tdi swap trucks on facebook is the place to be if you're considering a swap. But the only possible way to do a swap is to buy say an entire 99 golf tdi and tear it apart.