'94 FZJ80 Conversion to Biodiesel / Vege-oil burner....

[Cruiserhead05]

E and Bruce are right, 22 is optimistic.

From all i have read and been told by guys with 4BT trucks, high teens are probably what you will see. However; gearing, weight, tire size and elevation seem to all make big differences in real-life MPG

Having said that, i met a local guy with an '85 F250(2WD) powered by a 4BT yesterday. He said his truck weighs right at about 7k lbs and he has managed to get 25-28mpg on this first two tanks! (does that kill the whole weight and elevation argument?)

 

[cruiser-poor]

WVO or SVO is basically too 'thick' to run in most vehicles, except for instance early 80's mercedes diesels.

Actually, even with those. The OM617 engine is fairly tolerant of abuses like running unheated vegetable oil, but only to a point. It's considered best to feed even those robust injection pumps filtered, dewatered VO, heated to at least 160 F to get the viscosity down to around that of dino diesel.

 

[alaskacruiser]

from 13 to 22? is that for sure?

E and Bruce are right, 22 is optimistic.

I agree; that struck me as overstating the mileage gain.

1. From Proffitt's Cruisers 80-series 4BT Conversion Page:
"Approximate fuel mileage is in the mid to low 20s (though we have had some reports of as high as 27 mpg when driven cautiously and/or on rigs with 33" tires or smaller)."

2. Grease Cruiser reported: "The last couple of 80's we did were getting low 20's mpg."

3. latoyota had a 4BT conversion done on his 80 (and another referenced) by Proffitt's, drove it from CO to CA, and reported: "The two trucks averaged around 22mpg on the way back, but we were not gentle on them, cruising at 80-85 mph on the way home over all the passes and everything."

Even considering some of these trucks are part-time conversions, I'd say 22MPG sounds achievable, maybe not conservative, for a fulltime rig (as past part-time conversion threads have shown minimal fuel economy gains).

 

[peepers]

How do you turn wrenches through a telephone?

Oh thats right, telecommuting is for people who do not work for a living.

 

[Cruiserhead05]

1. From Proffitt's Cruisers 80-series 4BT Conversion Page:
"Approximate fuel mileage is in the mid to low 20s (though we have had some reports of as high as 27 mpg when driven cautiously and/or on rigs with 33" tires or smaller)."

2. Grease Cruiser reported: "The last couple of 80's we did were getting low 20's mpg."

3. latoyota had a 4BT conversion done on his 80 (and another referenced) by Proffitt's, drove it from CO to CA, and reported: "The two trucks averaged around 22mpg on the way back, but we were not gentle on them, cruising at 80-85 mph on the way home over all the passes and everything."

Even considering some of these trucks are part-time conversions, I'd say 22MPG sounds achievable, maybe not conservative, for a fulltime rig (as past part-time conversion threads have shown minimal fuel economy gains).

This is why i addressed the weight/elevation/gearing part of it. If you talk to guys who currently own and drive 4bta powered 80's i think you'll find some different, real-life numbers. What mpg you get in CO, you wont get on the coast of CA, etc.

After some long talks with proffitt's, i've come to the realization that my fully weighted 80 on 35's wont be getting 22mpg gallon here in VA

 

[IdahoDoug]

I think there are a lot of unaccounted for costs in these diesel conversions and I'll make a comment on Alaska's to that effect since he asked. First, operation of a diesel is generally lower in terms of fuel purchases, but higher in terms of maintenance and repairs. So, you may find that by the time your 6 year actual real world operation of the vehicle is up, you have spent an additional $1000 on special filters, higher cost oil, shorter oil change intervals, fuel/water separators, diesel injection pump service and batteries. Then, let's toss in a random failure such as an alternator. On a gasser, you could buy one at Schuck's for $80. An alternator on a diesel is perhaps $450. Atop this, there are some invisible costs such as the total of 10 days the vehicle might sit over this 6 year period while you track down a radiator hose or fan belt or widgit valve for an engine that is scarce, or even never sold here in the US. By this, I'm trying to have an accounting made for a specialty vehicle for which you cannot replace a fan belt that tears while you and your family are heading to Grandma's 300 miles away. What's it worth to you to no longer have a vehicle you are not afraid to drive 2000 miles at the drop of a hat? My brother in law's 93 80 series rolled over 320,000 miles while he and his family drove it on a 3000 mile trip last month - leaving their year old BMW in the garage. He knew that if it puked up anything from a radiator to a water pump that he'd likely get whatever he needed at any of the 50 Toyota dealerships he passed along the way.

Finally, there is the entire point of the conversion to address rather directly. The point is to reduce operating expenses, right? With the above points I've eroded that a bit by redirecting discussions away from just fuel savings to consider the TOTAL added operating expense of a diesel engine. By the way, a great way to get a grip on that is to call a dealer that sells a diesel truck and ask the service department what the total cost to maintain a diesel engine is over a 120,000 mile period. That's where you'll learn about fuel separators, injector service, injector pump service, the cost of oil changes and their intervals, etc. Then ask the same for a gasser - that's where you'll be told there is zero maintenance except fluids and recommended spark plugs at 100,000 miles. Gas engines have come a loooooong way.

Anyhow, back to my point. If the point is to reduce operating costs of your current vehicle, how about this:

Remove all excess gear, including the third seats, roof rack, etc
Next time you purchase tires, get a stock size or slightly narrower
Next time you change oil, use synthetic

And finally, SLOW DOWN. Here are some numbers I stole from an old post by Craig Vincent on the old 80's Cool list. He calculated the 80s frontal area and drag coefficient and charted out the horsepower at each speed it required to push an 80 along. His numbers show that reducing your freeway speed from 75mph to about 68 would reduce needed horsepower by 29%. If you're getting about 13mpg at 75 (I do), then you would get around 17mpg. Easing your around town driving as well, you might end the 6 year test by reducing your annual fuel costs by $1200 (15,000/13=1100 gallonsX$3.50=$4000-29% done in my head). After 6 years, you've saved $7200 with this strategy, where the diesel conversion saved you $0 at this point because that's where the whole project paid off (before adding in all my above hidden costs, BTW). The beauty of this is you do very little and it costs you nothing, plus you retain the factory reliability of an unmolested 80.

Every decision should be made in the context of what choices you have, and one is to optimize the vehicle you already own for mileage. Tough to do on an 80, but possible IF THAT'S REALLY YOUR GOAL.

I realize there is an unaccounted for coolness factor to having a diesel 80. No question. But I want those considering this to reduce their vehicle budget to understand that there is a little analysis you should do before opting for this strategy. And if you do this analysis, you may find the project will not save money at all due to the initial investment and the presence of an alternative (optimizing your current vehicle and altering your driving habits) that narrows the gap for free.

DougM

 

[alaskacruiser]

This is why i addressed the weight/elevation/gearing part of it. If you talk to guys who currently own and drive 4bta powered 80's i think you'll find some different, real-life numbers. What mpg you get in CO, you wont get on the coast of CA, etc.

Cruiserhead- if anything, the fuel economy numbers from Proffitt's in CO would be lower than what I would see here in CA due to the elevation change, correct?

As for weight/gearing, I have minimal mods (stock gearing, 33" tires, and an ARB), so I would think my fuel economy would probably be closer to the upper end of the range.

I would love to hear from 4BT-converted-80-owners as to real world fuel economy numbers, the mods they've done to their rig, their gearing, and elevation. I just asked latoyota if he would post up his numbers (he's in CA). If anyone knows someone with a 4BT-80, please ask them to post up, as well.

I guess I should have stated, for my purposes (and a lot of us on this forum with just the moderate OME 2.5", ARB, 33" tire mods) it seems that 22MPG is achievable. Correct me if I'm wrong, but I believe the numbers from CO would only be pessimistic vs. the numbers we'd see in CA due to elevation.

 

[cruiser-poor]

Alaska, those are impressive mileage claims. I can't dispute them, having no experience with this.

I will say that my '81 300GD gets about 18 mpg highway and even my little '85 300D sedan gets 27. Maybe the Cummins engines are more efficient.

Overall, I still think IdahoDoug and beno are on track here.

Also don't forget the pitch-black oil these things tend to leak on your garage floor.

 

[Cruiserhead05]

Alaska,

It's the other way around. From what i have been told from proffitt's, the colder, more dense area at higher elevation allows the 4BT to run more efficiently. Therefore, mpg would theoretically decrease as you get closer to sea level. This has been confirmed by those i've spoken with on a personal basis.

Additionally, i believe some of the high-end numbers that float around are from those with 33 inch tires, but since the 4bt swap REQUIRES a minimum of 4" of lift, 33 might look kinda silly. To each, his own!

As for doug and beno's point. I agree 100%. However, for me there is the already the expense of reviving my high-mileage 1FZ/A442F, so why not take that money and put it into a system that will operate more efficiently and has the potentially to run alternative fuels?

 

[latinoguy]

I think you would have to start with a diesel engine first....Then there are businesses that can do this conversion.... There is a book (haven't read it) that documents the Malloy brothers (pro surfers) who drove all of Baja on a BioDiesel converted Ford truck (I think) but the engineers who did the converstion (I think they are in granola & Birkenstocks loving Santa Barbara) If I recall the converson cost like $3K....

The cool thing, watching the faces of restaurant workers as the biodiesel converted truck pulls up requesting their old, burnt crisco, vegetable oil so they fill up....real story....the fuel is now free

 

[latinoguy]

The book I am talking about.....
Amazon.com: Bend to Baja: Books: Jeff Johnson

If I also recall.....the engineers were able to convert MOST diesel engines.....

 

[alaskacruiser]

Alaska,
It's the other way around. From what i have been told from proffitt's, the colder, more dense area at higher elevation allows the 4BT to run more efficiently. Therefore, mpg would theoretically decrease as you get closer to sea level. This has been confirmed by those i've spoken with on a personal basis.

1. I doubt the colder air plays a large role, as cold air intakes provide minimal fuel economy improvement.

2. Your statement about air density being greater at higher elevations is incorrect. "Air density decreases with increasing temperature and altitude." Hot and High.


Would be interested in any evidence to the contrary for the 4BT setup, though.

 

[Grench]

Biodiesel = hip

Finally, there is the entire point of the conversion to address rather directly. The point is to reduce operating expenses, right?

Umm... I think the original poster may have had a different objective. To be cool & hip & brag about how his 5,000 lb cruiser was actually environmentally friendly because it is bio-diesel which makes it better than a hybrid, right?

We (me included) all wish that Toyota had brought turbo diesel 80s to the US. The fact is though that their marketers made the right choice in -not- bringing them. The initial purchase audience for the majority of these sold in the US would have been aghast at the smell, noise and general 'trucker' connotations of diesel.

Would I like a diesel? Heck yeah. Would the doctor, broker or ??? who leased it originally? Not likely.

Is it 'green' to do a swap? Ummm... don't think so.
Is it 'cool' to do a swap? Oh yeah.
Is it 'cool' to run (or be able to anyway) biodiesel? Sure. For now.

 

[IdahoDoug]

Brandon,

Regarding reviving your FZJ (which I agree moves the needle a bit to improve the economics of such a conversion), it's worth noting that these gasser engines and trannys are so cheap you could likely spend $1200 from a salvage yard and slap a 100k drivetrain in your truck. No connection issues, minimal down time (vs what - a month for a conversion?) and you could even PM the head gasket in a few hours extra time if you wanted before install. So for 1/10th the cost you're back on the road in a few days versus at the beginning of an investment of $17,000 that may pay off 6 years from now. Or not.

I didn't know about the lift requirement of 4" until now. That is a rollover issue for a DD to me that should be part of the consideration and the truck will no longer fit in a standard garage, or get into a parking garage either.

The real world fuel economy of the diesel conversion should also come under some scrutiny since those kind of numbers are better than some brand new diesel trucks. Makes me wonder if they're inflated a bit by people's natural tendancy to quote a "best ever" economy number rather than the average fuel economy over a year's use. Jeep's brand new Grand Cherokee diesel is rated at 23mpg highway, 19 city for instance. The GC has a smaller frontal area (esp compared to a 4" lifted 80 on 33s), weighs 1000lbs less, is on mpg enhancing highway tires, uses Mercedes state of the art Blutec 3.0L diesel and has a transmission and drivetrain chock full of the latest mpg enhancing electronics. Yet it only gets a single MPG better than quotes here in this thread of a lifted 80 on 33s traveling at 80-85mpg through the mountains? The combined talents of Mercedes and Chrysler's engineering cannot match the achievement of stuffing an old school diesel into an old school chassis? Um...cough, cough.....

Among other things I have done over the years, I was the Worldwide Powertrain Planner for General Motors. I have to tell you that converting an 80 to a diesel is not going to save you any money and in all likelihood it will cost you thousands and thousands of your hard earned money. Please stop the madness on this diesel thing.

DougM

 

[Cruiserhead05]

1. I doubt the colder air plays a large role, as cold air intakes provide minimal fuel economy improvement.

2. Your statement about air density being greater at higher elevations is incorrect. "Air density decreases with increasing temperature and altitude." Hot and High.


Would be interested in any evidence to the contrary for the 4BT setup, though.

Alaska,

I am strictly relaying the information i have been given by those who are qualified to comment on this issue. While I do not claim to be an expert on air temperature and density and there roles in engine efficiency(be it gas or diesel); i do know for a fact that those 4bt powered 80's kept at higher elevation got better mpg then when operated closer to sea level.

 

[cary]

I'm just going to chime in here:

1) I agree with Idahodoug that doing a conversion is not cost effective.

2) One thing that nobody is talking about is do you really want to keep an 80 that long. Yes they are great off road vehicles, but by the time that yours reaches 250k are you really going to want to dump 12k+ into it for an engine conversion, that still leaves you with a worn interior, needing paint at some point, and other worn components. I know that I am at the point where I am maintaining my 80 and waiting in the next year or two to move over a 2003+ 100 series.

 

[Cruiserhead05]

Doug,

Thanks for the input. I always enjoy reading what you have to say because it's rather lengthy, which i enjoy.

As i said earlier, you will get no argument from me on the speculated mpg of the 80 diesel swap; knowing in my head if i even go through with this that i will likely be seeing 18-20mpg.

I'll preface my response to another aspect you brought up by saying that I have researched what to do with my 80 for nearly 2 years now, wanting to see the options i had, in an effort to make the best choice, for me.
Picking up a used driveline(engine/trans/tcase) was one of the first options i looked at. In all my searching, i have not seen complete drivelines for $1200, or even close to that. I had factored roughly 2000-2500 for an engine and maybe $1k for trans and tcase plus labor to have it swapped(i unfortunately have neither the time, help, nor tools to take on something like this)

Another topic you touched on earlier was the cool factor, while i'm not pursuing this in an effort to be cool, there is some draw about being different. Not to mention the additional power would be nice. My 80 is a dog in summer heat!

In response to cary,
I certainly hope to keep my 80 as long as possible. To me it is the most versatile vehicle i have, and it's 10-12mpg avg is the only thing that stops me from driving it. For being 13 yrs old and having over 300k miles it is still extremely well kept inside, the paint is great and everything is very tight. But again, this is my own personal opinion.

 

[rtarh2o]

The thing that is being overlooked is the added value of a good, clean, well running diesel conversion.
I found a 94 FZJ80 with a bad engine not too far from me, it has about 130,000 miles on it (strange, broke a belt, wrapped around water pump and overheated) The interior was excellent as was the rest of the car so I decided to buy it for $3,500. I decided to go with the GM 6.2 diesel for a number of reasons but mainly availability,cost and conversion parts. I found a military take out engine for around $750, a rebuilt 700R4 transmission for $750, adapters for about $500 (used off of the mud classifieds) I also bought new accessories (A/C, alternator, p/s pump) the brakes replaced, the transfer case serviced, and I installed new shocks and springs. I probably have another $5,000-$6,000 on top of my purchase price of $3,500. My goal was $10,000 total and that is about where I will be after I buy my tires and exhaust system.
Granted some conversions might bring more money than a 6.2 but I strongly believe that if I were to sell my 94 (assuming it runs as well as I hope) it would bring more than my investment. I wouldn't be suprised to see it bring close to $20,000 (crazy things happen on ebay!) Before I decided on the conversion I spent about 6 months looking for a diesel SUV, bottom line is you just can't find anything as nice as a diesel 80 for under $20,000.
I consider this my "new" car, I drove a 94 FZJ80 up until about 18 months ago and sold it because I got tired of the mileage. I bought a Volvo wagon for about the same as I am going to have in my "new" diesel 80. I am selling the Volvo for about $3,000 less than what I paid for it 18 months ago. If I decide to sell my 6.2 FZJ80 18 months from now I will probably make a pretty good profit on it plus I am setting it up to run on WVO so I will have very low fuel costs. Maybe I am just biased since I have already made the jump but I can tell you this, the smile on my face when I drive my diesel cruiser the first time will be worth whatever it cost me!
Until they start selling good diesel SUV's in this country I don't think you can go wrong with a conversion, even if you have to pay to have it done, the waiting list at all the conversion shops is proof positive!
Just another way to look at it
Rusty

 

[IdahoDoug]

Rusty,

Very cool. No matter what anybody's position on conversions is, it is always impressive to see somebody doing this themself at home. I'll look forward to hearing how the project ends and what it's like to drive. Bravo and best luck on it.

DougM

 

[rtarh2o]

Thanks, I am not a great mechanic by any means, alot of the stuff I see on here really impresses me. I am not afraid to tackle most anything and have the space and occasionally enough time to devote to it. It has been a 3 month project and is nearing the end. I has been a great learning experience and as stated here quite often you really know your vehicle when you work on it yourself. The best thing about the 6.2 is the simplicity of the pre-electronics. Routine maintnence will be much easier on this than the 1FZE ever was. The diesel is really a simple engine. I am looking forward to finally driving it. I have some pictures of the beginning of the swap (6.2 conversion begins) and hope to update it in the next few days.
Rusty