Bumber Hitch for Aux tank advise needed

[Jeff Bayley]

I need to put a 100 or maybe 125 gallon tank on the back of the bus. It will be custom fabricated out of aluminium and get tall and long so as to not have to be too thick. I'll probabley need to remove the single Reese hitch and put a double or maybe the single can be left and two additonal ones added to each side (I don't know) what the hitch place can weld up yet but to keep it stable I need more than just the center hitch to keep it from tetering (800 pounds). I'll bracket it so I can fold it down if I need to open the bay doors.

Anybody know of a partial component I can use to build around this ? Maybe a bike carrier on an electiric or hydraulic winch would be suitable and I could make the tank more think and less high and use that to let the tank down in case of needing access to the engine.

[Darl-Wilson]

Jeff, it might be helpful to know what type of liquid you will be transporting; flammable, etc. Will you need a certain height for filling the container and where must it drain? Will it be removed when empty? Many years ago I fabricated a device to do something similar to what I think you may need by building a 'triple-hitch' that was bolted to the frame and had 3 2" receivers.

You must have access to the engine compartment and another consideration is that it cannot stress the frame. As Jon aptly pointed out in another post weight on the rear could cause movement in cap and other riveted areas.

I think if you give us more information you will get an assortment of suggestions, probably one of which would suit you needs.

Darl

[Jon Wehrenberg]

Jeff, You already know I am a naysayer so this should not surprise you. I can think of why you are attempting the wrong thing on so many levels.

If you wish to haul a tank full of McDonalds french fry grease (nowhere near the quality of the grease at some Chinese restaurants) you at least need to consider access to the engine. That stuff is dirty and Ken Z's brother in law gave us an excellent seminar at Pahrump on the use of that material and it involved changing fuel filters about every day or 400 to 500 miles. Leave room to open the doors because every day of travel translates into fuel filter changes.

For every 100 gallons of stuff you haul you are dealing with around 700 pounds plus the weight of the tank. In itself that is not good because you are taxing the structure that Prevost limits to 1000 pounds. But hanging it back there means it is not getting heated. It needs to be warm. It will gel. The good news is it is where you can get at it because it is going to get some crud collected in it and that will also need cleaning.

It is already a fact that you can run a lot of different materials through a mechanical diesel engine. You cannot run stuff like that through a DDEC engine. On a mechanical engine if you want to go faster push harder on the pedal. When it starts to misfire, such as going up a hill, switch back to diesel which you need in addition to vegetable oil. When the bus is on the flat, switch back to veggie fuel.

But the DDEC is measuring what is happening during the firing of the engine and the computer adjusts timing and fuel delivered to respond to the electroninc pedal. It is not calibrated for a tank of veggie oil, animal fats, or whatever else you will ladle out of the grease tank.

If you have the optional aux fuel tank that might be the place to start storing your veggie fuel. You can more easily warm it, you can make the complex plumbing enclosed so it will not gel in cold temperatures and your bus will not look like Jed Clampett's. If you succeed in having the first Prevost to run a DDEC engine on Wesson oil post pictures and tell the world.

[Coloradobus]

Jon,
Reading what you just told Jeff, is the 8V a mechanical engine that will allow you run veggie oil it with less headaches than what you described above for the DDEC?

[Jon Wehrenberg]

In Pahrump Ken Z's bro-in-law indicated veggie oil would not work in a DDEC engine. At least that was the understanding I had. I believe that to be true because a mechanical fuel injector meters fuel in a completely different way than the computer controlled fuel solenoids at each cylinder.

His bus had an old mechanical Detroit. I forget which model.

There was a lot to using veggie oil in his bus. First it has a complex system of fuel lines and valves. The bus starts on diesel and only when the veggie oil is warm does he switch to veggie oil. He runs coolant through the veggie oil tank in a heat exchanger. Once warmed up he can switch to veggie oil which has already gone through some filtration and separation before he put it in the bus, and then it goes through more filtration and separation. The stuff is nasty so he changes filters at least after ever day of driving.

His set up required the transfer of less clean veggie oil to a second tank from which the oil was pumped to the engine. Since it has a lower BTU content than diesel it will not perform as well. Going up hills for example he has to switch back to diesel because the veggie oil starts to make the engine misfire.

The guys that the TV stations feature on a slow news day that are driving their VW diesels make it sound like you just pour veggie oil in the tank and off you go. Not true. This fellow had a very complex fuel system piping arrangement, multiple fuel tanks with internal heat exchangers, extra fuel filters and hours of labor collecting this stuff, separating the solids and water from it before he transferred it into the bus, plus the labor and cost to change filters daily. He had a big Racor like the ones we use that had to be serviced daily. I believe he had several thousand invested in his system and except for the tanks I believe he assembled the whole thing himself so you can imagine how involved it was. It took up an entire bay.

What was not answered was the long term impact on such a conversion. As we go from the diesel fuel of the past and begin seeing the low sulfur and the blends with ethanol we see an impact on mileage. That's no surprise because the BTU content of a gallon of diesel compared to veggie oil is much higher. But we are also beginning to hear of issues relating to injector lubrication and problems with seals and gaskets not made to withstand the fuels of today. Our current fuels are not just to burn, but they perform some lubrication functions for our engines as well. I think the jury is out on the long term affect of veggie oil.

[Jon Wehrenberg]

This is a good article that covers the topic fairly well because it discusses what is involved and recognizes the issues to be dealt with

http://journeytoforever.org/biodiesel_svo.html

[Jeff Bayley]

John-

I had seen that link you supplied before, forgot to book mark it and just found your post again. Thanks. I need to read it again. Your points on the electronic measuring of the fuel very well may be true but regarding lubrication, how can you say that the lubrication is less and not better with veg. oil ? Just by rubbing diesel and veg oil betweeen your fingers, can it not be clear the veg oil is much more slippery ? Everything I've read says's it provides better lubrication. The mileage is less that's for sure.

Regarding the rear tank (if I ultimatley decide to advance), that is just a feeder tank for the already refined fuel. The pick up truck I tow would be used for collection and have the filtration system on it with (as you mentioned) a Raycor or similar final filter for good measure on the business end of the engine.

I'm considering taking two Prevost and an 18 wheeler coast to coast to trade shows. If I find out if it will work, the pick up truck and be the chase vehicle to supply all three rigs.

I was thinking of calling Detroit to get a 2nd opinion on the whole computerized mixing, detecting, issue you bring up. I don't fully understand how the WVO would screw that up. Would it not take it's measurements when using the VO and adjust accordingly or are you saying that it is outside the evenolope of adjustment as regards the computer made to operate within the tollerances of diesel ?

[Jon Wehrenberg]

Jeff,

Please call DD and post their response here. If you want to discuss this with the man that did the seminar in Pahrump his address is mrz@pocketmail.com. He is running veggie oil in his 8V71N.

I think you will find DD telling you not to do it. But let us all know the outcome.

[tdelorme]

Are road use taxes not an issue with veg. oil??

[wrongagain]

If I can pipe in here,
If you are going to tow a pickup truck why not use a tank in the bed of the truck and rig some sort of fuel line to the bus.
Or, surrender one of your bays for a tank there.
Other than that, it seems like a lot of engineering for some DOT inspector to red tag.
I'm dying to know how this turns out.