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Old 03-22-2016, 04:03 PM   #1
Join Date: Nov 2015
Posts: 35
Adventure Bus 2016 - Veggie build

Well, I have been lurking around and asking a few questions, but I guess I will go ahead and start a build thread to document the project

I am a senior at Auburn University studying mechanical engineering. I have had a passion for exploring God's creation ever since I was young when my family would go on camping trips, hikes, and bike rides. Growing up my passions have only grown, I have become enthusiastic about mountain biking, backpacking, fly fishing, climbing, and other fun outdoor activities! I have had the opportunity to ride my bike on some great terrain in Alabama (my home state) as well as Wyoming, Virginia, and British Columbia. While biking is one of my favorite outdoor activities, I have also gotten to see some amazing places backpacking, and fly fishing. I have also developed a passion for photography and videography over the years and am not an expert, but I really enjoying capturing beautiful scenes and adventures.

Early in the fall 2015 semester, Jonathan and I decided we needed to do something big with our lives. We both had dreamed of a road trip across the country for years, but we wanted to do much more than just satisfy all of our desires for adventure and recognition. We decided to make the main focus of our trip bringing glory to our God and Savior.

We both have a zeal for exploring God’s creation and we are both studying mechanical engineering and nearing graduation. So we decided to make good use of our passions and talents on this trip. After a series of events consisting of everything from prayer filled consideration to Jonathan’s crazy ideas to job fairs at auburn, we decided on the ‘big thing’ that God was leading us to do with our lives. We decided to buy a school bus, design a system that would enable us to use waste vegetable oil as fuel, and explore the country seeking God’s glory the whole way.

November 2nd, 2015:
We bought a bus.

Its a 1997 International 3800 with a 7.3 liter t444e turbocharged diesel with around 140k. The chassis is a bluebird conventional handicapped chassis. 2600 dollars and It came with a wheelchair lift which we later sold (cha-ching!). It is going to be perfect for our conversion.

Handicap bus, only had 4 or 5 rows of seats

The project can best be divided into at least 3 main parts, filtration system, veggie conversion, and RV conversion.


We are both in engineering so we did extensive planning/designing of our filtration system and veggie oil conversion..

::technical stuff::

In order to run the bus on waste vegetable oil, we determined we needed to filter the wasted oil to 10 micron absolute. By increasing the viscosity of the oil with heat and simulating a gravitational acceleration of 4,265 m/s^2 on the oil using a centrifuge, we were able to drastically speed up the settling velocity.
Terminal velocity of a sphere falling through a fluid given by stokes law:

Rho_p: density of particle
Rho_f: density of fluid
Mu: Dynamic viscosity of fluid
g: Local gravitational acceleration
R: radius

For a 50 micron particle in rapeseed oil at 24 C, the settling velocity is as follows:
Mu = 78.8 cP = .0788 kg/m*s
Rho_p = 1200 kg/m^3
Rho_f = .9073 g/mL = 907.3 kg/m^3
G = 9.81 m/s^2
R = 2.5e-5 m
V_s = 5.06 e -6 m/s = .3036 mm/min

For the same particle at 70 C and gravitational acceleration of 4,625 m/s^2
V_s = .00963 m/s = 578 mm/min

::end of technical stuff::

We designed and manufactured the centrifuge using parts from the rear axle of a jeep for the bowl and shaft. The centrifuge uses an electric motor that spins at 1,750 rpm and exerts an acceleration 435 times greater than earth's gravitational acceleration, the oil forcing unwanted particles and water to the wall of the bowl and allowing clean oil to be sprayed out the top. This oil is then collected in a sump where a control system allows it to be pumped out through a filter and into a clean oil tank. The system is protected from overflow using a 107db alarm.

Not the best picture but its all I have, it has performed great, filtered 550 gallons so far in 2 days. We got all our vegetable oil from some local folks who were getting out of the veggie oil thing, they were very nice and helpful

layout of the filtration process:


After researching, we determined if we could get vegetable oil to be similar in viscosity to diesel fuel, we could effectively use it as fuel. This means the vegetable oil must be heated to a temperature of around 175 F before it can be injected. After many revisions, we arrived at a design. The concept of the design is as follows:
-Start the engine on diesel fuel
-Allow engine to heat up
-Use hot engine coolant (180-200 F) in a closed heat exchanger with vegetable oil
-Use filter heater to warm oil as it passes through filter
-Ensure that vegetable oil has been appropriately heated

To achieve this, we used two fuel tanks along with a series of valves, this can be seen in the following figure:

We opted to do 2 separate filters where veggie will never enter the stock filter, we did this because the stock fuel bowl is HUGE and would be tricky to clear all the veggie out of it.

Scored a stock tank out of a similar bus about 1.5 hours from where I live:

We tested the system the day we plumbed it and believe it or not, everything worked with no issues! We were well in the temperature range we needed to be in (70-80 C) to maintain a viscosity similar to that of diesel. We are using a flat plate heat exchanger with insulation wrapped around it along with a filter heater.

Goals for the RV conversion are as follows:
-Sleep up to 5 on the bus
-Store adventure gear, notably, 2 dirtbikes, 4 mountain bikes, 2 kayaks
-Outdoor grill, Gas/electric, and stove plumbed to propane
-Seamless electrical system, able to plug into shore or run use batteries
-Always have 110v ac and 12v dc available.
-Small living area
-Space for compact filtration system

We were able to get a gas/electric fridge, converter, lots of wiring and outlets, sink, air conditioner, and miscellaneous other things all for free from this rotting camper that was at my grandfathers farm.

We also scored some nice 12x1 pine that has been awesome for the conversion.

The layout is as follows: a double bunk in the back passenger side, top bunk only in back driver side. underneath this bunk will be a filtration system and storage. infront of the top bunk is a bathroom and fridge, then across from that is the kitchen. In the front of the bus will be a living area with a couch, navigators table and, for our trip, we wil be taking a 275 gal tote full of oil.

here are some pics of what has been done so far:

The bunks have a nice large storage area under each one, it worked out very nice! Not sure how many of yall have these gas/electric fridges, but ours only works if it is very level.. bit of a pain but its nice when the bus is level anyway.

I designed the electrical system such that all the switching is done automatically when you hook up. We have a 30 amp system.

So yah, that is pretty much where we are, I have been working on installing the electrical recently and I am very close to finishing it up. Hopefully everything works as we plan!

Just the other day we cleaned it out real nice and put Christmas lights in it and a tv and propane stove... it was a good time, watched a movie then woke up to bacon. Cant wait till we get things a little more permanent. Its gunna be fun.

Well if anyone made it this far reading... cheers to you! and thanks for checking it out, hopefully more details will come in the following weeks, everything has to be done by may 14 or so but I don't have ample time to work on it.

more pics here
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Old 03-22-2016, 05:44 PM   #2
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If I could critique your set up a bit-You're overdoing some things and under doing others.
The good: the 7.3 (444) is the perfect motor for veg. One of the reasons is fuel goes thru the cylinder head to get to the injectors. And its in there long enough to warm it up to all the temp it needs. As long as the fuel is thin enough to get to the engine, it will run on it. All the heat you have beforehand is pretty much unneeded unless you are going to be doing a bunch of winter travel. ( A forum I used to go to thats not very active anymore had a guy that had put well over 700k on a couple 7.3's on veg. Above 40 degrees he would do nothing-just put veg in a second tank. He'd even start cold on it. He'd heat the tank below that temp just to get it to the engine. I wouldn't go that primitive, but knowing what you can get away is what lead me to the 7.3) I have separate remote filters for wvo + fuel-and a delrin slug in the original fuel bowl just to take up space. That way I get the the stock heater + plugged filter warning on the dash-and more engine heat.
The not so good: You may have passed that much fuel thru the 'fuge-but it would have to be the most magic one on the planet to get that much fuel CLEAN in one pass. I had a buddy centerfuge some oil for me while my system was down. He had a small set up-it takes him 3 days of steady running to to do 55 gallons. The $1500 unit I looked into buying would only do 55 gallons in 24 hours-heating the oil to 150 + doing at least 2 passes. I think you better do some forum searching before you load 1500lbs of wvo on the bus expecting to run it without plugging filters every 100 miles.
Don't make a fuss-just get on the bus!

my bus build
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Old 03-22-2016, 06:03 PM   #3
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I second that with a HUGE emphasis on the water required to "clean" the fuel. 10 years ago I had a high quality centrifuge and it required three passes as a MINIMUM, usually five, before the oil was close to being "useable". Also keep a VERY keen eye on the fuel injection distributor pump going out-of-spec. Tolerances are in the ten-thousandths of an inch. Water will compromise those tolerances very quickly.

Just sayin'.......

Firearms stand next in importance to the Constitution itself. They are the American people’s liberty teeth and keystone under independence. — George Washington
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Old 03-23-2016, 08:51 AM   #4
Join Date: Nov 2015
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Thank yall for reading and replying. And thanks for the critiques.

for clarity, I have been running oil through the centrifuge at a rate of around 20 gph.

I am fairly confident in our filtration, but these comments have caused me some concern so I will do some more calculating, specifically with filtration of water. Also, when I get a chance I am going to do a little experimenting with my filtered oil to see how clean it really is. So far I have passed it all through a 5 micron filter (the same 5 micron filter) with out any issues at all which is what makes me believe it is pretty clean.

I have been filtering the oil at 130-150 F.. compared to room temp this speeds up filtration by a magnitude of 4 times. I also have a larger bowl than any centrifuge I have seen on the market.. its around 4 inches deep and 10 inch diameter I believe. The added depth means the oil should be in the bowl longer because it is inserted at the bottom, the larger diameter means a greater normal acceleration.

Another thing to mention, all of the waste oil I have is remarkably clean before I filter it. All from the same source: a church that uses it on 1 occasion then throws it out. The oil has all settled over quite some time as well.

Also, M1031A1, the 7.3 uses the high pressure oil pump to pressurize the fuel at the injector, using a heui style injector. So my main concern is messing up the expensive injectors.

I have run some numbers to get a better feel for centrifuging.
-the density of the particles is what I would consider to be a very conservative estimate.. That stuff when glopped up seems pretty dense to me.
-I have no clue what size the typical water particle is in oil, so I'm sticking with the assumption that filtering to 10 micron is acceptable despite the fact that water molecules can be much smaller

So it looks like it would take a 10 micron particle about 1 minute to reach the back of the centrifuge and a 10 micron particle of water about 3 times that. This is good to know. I am very curious to know more about how the oil is flowing through the centrifuge, ie if a dirty particle is inserted at the bottom, what is its path to the back of the wall? Judging by the location of the sludge on the centrifuge wall it goes STRAIGHT back and stays at the bottom.. smaller particles I imagine behave a little differently though.

Summary: I need to check how clean my filtered oil is. Water takes considerably more time to centrifuge out.

thanks to you more experienced folks for leading me to think through things more.
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Old 03-23-2016, 10:43 AM   #5
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As I have cautioned many people in the past, while WVO seems like a great way in which to get fuel for free, the sources of WVO are getting fewer and fewer as time goes by.

More and more companies lease their vegetable oil and pay for any shrinkage. The company that owns the oil drops off new oil and picks up the WVO and processes the WVO for their own purposes.

Tim's Cascade Potato Chips in OR uses all of their WVO to fuel their fleet of trucks. They have since branched out and lease and process vegetable oil to further fuel their fleet of trucks. There is virtually zero WVO available within 150 miles of Portland and none of it is still free for the taking.

So while I applaud your initiative and creativity I would not include in your cross country plans the ability to find and use free WVO on your travels.

At an optimistic estimate of 10 MPG, on a 300 mile day you are going to need 30 gallons of WVO. At less optimistic but realistic estimate of 5 MPG, on a 300 mile day you are going to need 60 gallons of WVO. That is a lot of fryer fat!

I am afraid as you travel you are going to be spending a lot of time on the phone and the internet trying to locate sources of WVO.

I would suggest that time might be better used doing more productive activities.

Good luck and may God bless and keep you!
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Old 03-23-2016, 11:08 AM   #6
Join Date: Nov 2015
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Thanks for that reply and advice.

That is very good advice and I am actually not expecting to find any wvo along the way. Might give it a weak effort but not counting on it. Currently we have about 1500 gallons.. The plan is to fill our 65 gal tank + a 275 gallon tank inside + a 55 gallon drum in the back. That gives us around 400. When we drive to denver though, we plan to take an additional 400 gallons with us, burn 200 gallons on the way to denver and drop off 200 gallons in denver. This way, when we get to denver it will be, fuel wise, as if we are starting our trip from there. We will do a big loop out west then pick up the 200 gal in denver so we can make it back home! We will probly need an additional 200 gal or so to do the route I want to do, for that we can either buy diesel (likely) or possibly try to find some oil..

Main problem is that means we will have around 3 tons of oil on the bus for our drive to denver.... not ideal but it will be a 30 hour trip so we will just deal with it. We have carried that much before without issues.
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Old 03-23-2016, 11:32 AM   #7
Join Date: Nov 2015
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one more comment about the centrifuge..

WVO Designs centrifuge (link) claims to do up to 25 gph - one pass. They also claim to be applying 1200 g's to the oil. This is about 2.75 times more than the 435 g's my system does... Maybe I will proportionally match their flow to mine acording to g's. that would put me at 9 gph.

OR I could throw on a 3560rpm motor I have and be at 1800g's....
problem with that is its hard to get the oil in without it blowing right out because of all the wind currents in there
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Old 04-04-2016, 10:02 AM   #8
Join Date: Nov 2015
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Picked up about 500 more gallons of veggie oil this weekend
Really nice guy that gave it to us, he also gave us a few nice 12 volt pumps, an IBC tank, a flat plate heat exchanger, a fuel feed/return solenoid selector valve and some other goodies! Thanks Tony!!

Also did a little work on the bus, here are some pics of how she looks:

Picking up oil, ended up being completely full of cubies

made some progress inside the bus

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Old 04-04-2016, 01:32 PM   #9
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Looking good!

I would say the hook on the ceiling to hold the bed platform up is a great way in which to put a good gouge in your head. Regardless of where it is in relation to the pillow I can still see it as a head knocker for sure.
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Old 04-09-2016, 08:09 AM   #10
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Sorry but I DO have to put my 2 cents in, you guys talk about wanting to help out mother nature yada, yada, yada...
Have been doing WVO for 10+ years, learned a long time ago the easiest, cheapest, least labor intensive way to filter is letting mother nature do the work.
I simply filter the oil through a strainer as I pour it in my warming tank (painted flat black, setting where the sun contacts it). Let it warm & settle over a few days/weeks, then let it gravity feed through my filters into my storage tank.
I use 55 gal. plastic barrels for my storage.

On another note, from what I remember those Powerstroke/T444's have a rubber diaghram in the fuel lift pump that will be eaten by WVO. You will need to use an elec. pump with regulator to by-pass the lift pump.
I have the older non-turbo 7.2, they run great on wvo.

Good Luck
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Old 04-09-2016, 08:12 AM   #11
Join Date: Oct 2015
Location: Duluth, MN area
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Should have kept your Handicap lift for lifting barrels of WVO into your bus!!! Wish I had one on mine...
Also hope your WVO fuel tank isn't steel...
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Old 04-30-2016, 01:28 PM   #12
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Really interesting build!

I'd love some more build details on your centrifuge!

I messed around a lot with wvo in the early 2000's. I want to echo what others have said: It's much harder to find in 2016 then it was in 2002. The renderers/disposal companies and restaurants changed their business model up, likely in response to us dirty weirdos offering restaurants free pick up of used oil. I'd love to hear how your on-the-road filtering goes. I'll probably hook a second tank up in my bus eventually.

FWIW, I used a dieselcraft centrifuge to flter. I had a wire mesh filter on my collection sucker, then did ~5 passes with the centrifuge. I checked how gunky the thing got after one pass and made adjustments based on that. Also, have to be there when the 'fuge spins down to catch the gunky stuff that tries to fall out on spindown. After the 'fuge, I used a 2 micron absolute on the transfer pump to the fuel tank, and used a pressure gauge on that to see how well the filtering had done. When I really had the system down, the 2 micron final filter would last months and months.

On steel tanks: they can allow a vo "skin" to form inside via some mechanism I never understood. I still used one, but had to have a way to clean it out. The other option is to make an aluminum tank; those don't seem to have this problem, but do have a problem of their own, ie, triple cost of steel, maybe more.

I used hose-in-hose coolant heated fuel lines. I imagine this is even more important on the long fuel line runs on a bus!

Finally, and most importantly: You will spill VO one day! No question. It'll happen. Plan you VO storage with this in mind. I see all those cubies on the floor, and I remember the smell and feel of trying to mop up warm used VO... a redundant spill catch pan is SO INCREDIBLY VITAL!

Good luck, keep us posted!
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Old 04-30-2016, 09:21 PM   #13
Join Date: Oct 2015
Location: Duluth, MN area
Posts: 15
Year: 1995
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Engine: DT-466 mechanical
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Not sure if your looking for me or the college boys, I have been doing WVO for 10+ years on my VW's & 7.3 Ford.
I don't use a centrifuge, as I simple use Mother Nature, gravity, & father time.
I let the WVO warm in the sun, then gravity feed through filters into my storage. I use 55 gal. plastic barrels for storage, prefer the white barrels, as I can see how full they are.
I also use a concoction of Methanol, Bio-diesel scum preventer, & preservative to protect the WVO.

Good Luck.
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