Plantoil/diesel conversion basics
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danalinscott

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Under construction...

 

Note: This is a new tutorial and can probably stand improvement. If you have a suggestion or question just post it below in this discussion and it will be answered. There are no stupid questions and if you don't fully understand something chances are that  a dozen others don't either. Please don't be afraid to ask "what do you mean by this?" or "can you explain that further." Questions like those will only make this more useful to everyone.

 

The majority of VO conversions of diesel engines running today are "two tank" conversions. This refers to the fact they have one tank that contains diesel fuel and another that contains VO fuel. The main aim of most of the components in a VO conversion is to add heat to the VO fuel passing through them in order to lower its viscosity. Since VO can be too viscous/thick to flow through a fuel line from the VO fuel tank the first heat adding component in usually incorporated into the fuel tank.

 

The tank containing diesel fuel is used to provide fuel to start the engine and fuel it until it is warm enough to safely run on VO fuel. (For more information on this go HERE)  By the time the engine temperature is up to "operating temperature" (typically 150°F to 190°F) waste engine heat is available to add heat to the VO fuel using the hot liquid coolant which circulates through the engine as well as the radiator and passenger compartment heating system.  VO fuel needs to be heated in order to lower its viscosity so it can easily flow through the fuel supply system and so it is able to atomize into small enough droplets to be efficiently combusted inside the engine.

 

The tank containing VO is where VO fuel begins being progressively heated to the point it can be used as fuel by the engine. In the early days large coolant "coils" were installed in VO tank that tended to heat all of the VO in them to very high temperatures ..eventually. It was soon discovered though that in cold climates it took much longer for liquid VO to be available at the tank outlet than for the engine to reach operating temperature. More recently it has been revealed that when VO is heated to high temperatures polymerization of the VO occurs. This may cause VO filters to clog prematurely. Most modern VO conversions concentrate  heat near the VO tank outlet...or use a heated fuel pickup in the tank itself. The heated outlet or heated VO pickup is the first conversion component that VO passes through as it travels toward the engine. The VO then passes directly into heated fuel lines.

 

In the heated fuel line VO is heated in order to keep it liquid enough to flow easily as it journeys toward the next VO heating component.  Heated VO lines are also necessary throughout the conversion so any VO which is solidified due to cold ambient temperatures (during the time the engine is not running) is liquefied enough to easily flow.

 

There are two types of heated fuel lines Hose ON Hose (HOH) and Hose IN Hose (HIH). 

 

HOH fuel lines are fabricated by simply bundling hoses which have hot engine coolant passing through them with those containing VO. The heat from the hot engine coolant is transferred through the walls of the coolant and VO hoses and into the VO. Flexible synthetic hose is usually used for HOH lines and the "hose bundle" is usually insulated with a flexible foam sheath to speed initial VO heating and conserve heat.

 

HIH fuel lines are fabricated by inserting the fuel line inside a larger diameter engine coolant line. Heat transfer is more efficient than exhibited by HOH fuel lines since heat must only travel through one hose wall and hot coolant surrounds the entire fuel line. However there is  the  danger of coolant leaking into the fuel and causing engine damage which is not possible if HOH lines are employed. HIH heated lines are also significantly more difficult to fabricate and install than HOH lines.  

 

Optimally heated VO lines should be used throughout the conversion since VO may solidify in any unheated VO line and so prevent the flow of VO through the entire VO fuel system.  The next most common component that the VO passes though is the coolant/fuel heat exchanger.

 

 

As the VO passes through the coolant/fuel heat exchanger its temperature is raised significantly. Since "waste" engine heat is the most abundant heat source available for raising the temperature of VO this is the component where most of the VO heating occur rs.

 

Two types of coolant/fuel heat exchangers are available, tube in tube (TIT) and Flat Plate heat exchangers (FP or FPHE). Of the two FP heat exchangers are much more compact and efficient. If space is very limited the clear choice is a FPHE. On the other hand FP heat exchangers cannot be fabricated by the DIYer and TIT heat exchangers can be easily fabricated using common plumbing supplies. After passing through the coolant/fuel heat exchanger VO is liquid enough to easily pass through a filter element. Therefore most VO filters are located after a coolant/fuel heat exchanger.

 

VO filters are necessarily heated filters primarily due to the fact that the VO inside them must be heated to a point where it is fully liquid before it can pass though the filter element. The filter element is the most restrictive point in the entire fuel supply system and so must optimally be able to heat the cold VO it contains to at least 100°F+ before the engine reaches operating temperature. Although fuel filters designed to be used with diesel fuel are also heated they are not well adapted to use with VO since the heating capacity is usually less than 1/4 what is required for VO use and the have an internal thermostat which only allows them to reach a maximum temperature much cooler than is necessary for use with VO. They are marginally adaptable at best.  There are however commercially available VO filters, adapters to add more heating capacity for commonly available fuel filters, and DIY options for fabricating VO filters capable of reaching the necessary 100°F+ temps.

 

Although it is possible to use a single shared filter for BOTH diesel  and VO fuel it is not generally  considered desirable to do so for both convenience and safety reasons. It is  desirable to install a dash mounted fuel pressure/vacuum gauge or indicator to provide a warning that your VO fuel filter is reaching a point where it should be replaced or is malfunctioning. Similarly a dash mounted fuel temperature gauge is also considered a very desirable option by many.  The heated VO travels from the VO filter to the Injector Pump (IP) where it is boosted to extremely high pressure and distributed to the  Injector Lines and fuel Injectors which inject the high pressure fuel into the engine itself. The last opportunity to heat the VO is as it passes through the Injector lines using Injector Line Heaters (ILH).  Not all modern diesel engines have Injector Pumps and Injector Lines.

 

Injector Line Heaters allow VO to be heated to temperatures where VO is nearly identical in viscosity to diesel fuel. It is not possible to add this heat to the VO prior to it passing through the IP since most IPs will absorb heat from the VO if it is hotter than the operating temp of the IP itself.  Most IPs run at a temp of 130-150°F and may experience accelerated wear if constantly operated at temperatures much higher than this.  Injector line heaters are essentially 12v electrical resistance heaters which are wrapped onto the individual injector lines and transfer the heat they generate through the steel wall of the injector line and into the high pressure VO passing through them. VO temperatures of as high as 280°F can be achieved in this manner which allows the VO passing through the injectors to be sprayed in a pattern nearly identical to the diesel fuel it is replacing. This allows it to be combusted as fully as possible thereby increasing efficiency and reducing carbon deposits in the engine which may significantly reduce engine life.

 

In addition to the above VO heating components other common VO conversion components include:

 

3 and/or 6 port remove fuel valves (motorized, manual, or solenoid operated)

 

Electric fuel pumps

 

One way valves

 

Temperature and pressure/vacuum gauges

 

Automated controllers

 

and of course

 

Wire, relays, and various types of electrical switches.

 

 

 

 

 

 

 

 

 

 


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Dana danalinscott@yahoo.com
Attilio

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Reply with quote  #2 
Hello Dana (and everyone else...).  My name is Attilio and I am very newly investigating beginning to use plant oil-based fuel in my '97MY FORD F-250.

By reading this and a few other related forums, I realize now that I made a huge mistake in purchasing the DSE product/info (which I haven't rec'd yet).  I want to get away from using petro-based fuels as cheaply and easily as possible and their product/concept seemed like the best way to do that.  Well, that is still my objective (i.e. cheap & easy).  But, I am willing to pay for convenience.  That is why I was seriously looking at a $8,000 biodiesel automatic processor.  The thing that I don't like about biodiesel is that it still requires petro-based fuel to be mixed with VO.

So, here I am now, liking the idea of 100% SVO/WVO as my new fuel.  And, wondering what is the best (i.e.cheapest & easiest) way for me to go.  I have spent the past couple days reading a lot of the info on these forums and based on my newfound knowledge from them, I have following questions:

1)  Because my vehicle has two factory installed fuel tanks and  I live in Florida (where is is always HOT) and my vehicle is used very rarely , primarily as a tow vehicle for my RV travel trailer and has very low mileage (approx. 50,000), Could I use one fuel tank for diesel/biodiesel and the other for SVO/WVO, without any (or minimal) modifications to the vehicle, by starting and running the vehicle on the diesel fuel and then switching to the VO tank after reaching normal operating temps?

2) If I could do #1 above, could I get away with not heating the VO by a means other than the heat of the engine running and our HOT Florida ambient temps?

#3) If I could NOT get away with #2 above, what would be the recommended bare minimum, ideally bolt-on, components that would be needed to make my idea work? 

Thanks in advance for the feedback and any input that you think may help me in my decision making process!

Ciao for now,
Attilio

danalinscott

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Posts: 934
Reply with quote  #3 

Quote:
Originally Posted by Attilio
Hello Dana (and everyone else...).  My name is Attilio and I am very newly investigating beginning to use plant oil-based fuel in my '97MY FORD F-250.

By reading this and a few other related forums, I realize now that I made a huge mistake in purchasing the DSE product/info (which I haven't rec'd yet).  I want to get away from using petro-based fuels as cheaply and easily as possible and their product/concept seemed like the best way to do that.  Well, that is still my objective (i.e. cheap & easy).  But, I am willing to pay for convenience.  That is why I was seriously looking at a $8,000 biodiesel automatic processor.  The thing that I don't like about biodiesel is that it still requires petro-based fuel to be mixed with VO.

So, here I am now, liking the idea of 100% SVO/WVO as my new fuel.  And, wondering what is the best (i.e.cheapest & easiest) way for me to go.  I have spent the past couple days reading a lot of the info on these forums and based on my newfound knowledge from them, I have following questions:

1)  Because my vehicle has two factory installed fuel tanks and  I live in Florida (where is is always HOT) and my vehicle is used very rarely , primarily as a tow vehicle for my RV travel trailer and has very low mileage (approx. 50,000), Could I use one fuel tank for diesel/biodiesel and the other for SVO/WVO, without any (or minimal) modifications to the vehicle, by starting and running the vehicle on the diesel fuel and then switching to the VO tank after reaching normal operating temps?

2) If I could do #1 above, could I get away with not heating the VO by a means other than the heat of the engine running and our HOT Florida ambient temps?

#3) If I could NOT get away with #2 above, what would be the recommended bare minimum, ideally bolt-on, components that would be needed to make my idea work? 

Thanks in advance for the feedback and any input that you think may help me in my decision making process!

Ciao for now,
Attilio


Welcome,
If you only plan to use this conversion in temps high enough to keep the wvo fuel completely liquid...yes..you can probably use the existing tank for VO fuel with very little modification.  And Yes..it is possible to use only coolant heat to lower the viscosity of VO fuel prior to injection. 


How well and how long it will run well on this depends on several factors.

What is the vehicle?

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Dana danalinscott@yahoo.com
Attilio

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Posts: 2
Reply with quote  #4 
Quote:
Originally Posted by danalinscott

Quote:
Originally Posted by Attilio
Hello Dana (and everyone else...).  My name is Attilio and I am very newly investigating beginning to use plant oil-based fuel in my '97MY FORD F-250.


Welcome,
If you only plan to use this conversion in temps high enough to keep the wvo fuel completely liquid...yes..you can probably use the existing tank for VO fuel with very little modification.  And Yes..it is possible to use only coolant heat to lower the viscosity of VO fuel prior to injection. 


How well and how long it will run well on this depends on several factors.

What is the vehicle?


Thanks again!  Mine is a"...97MY FORD F-250." 

If you were me and wanted to go the purchased kit route, what vendor would you buy from for this vehicle in my climate?  So far, I like what I see from Golden Fuel Systems (GFS) because they talk about "This system allows you to modify the front tank to run on SVO. This is one of the easier systems to install as the tank has a fuel level sending unit, the wiring for the switching valve is already in place and the cab has the switch installed."  (for under $1,000). 
danalinscott

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Reply with quote  #5 
Quote:
Thanks again!  Mine is a"...97MY FORD F-250."  


Please post questions on this conversion in the appropriate section provided under the Conversion info area about 2/3 of the way down the Home Page.

I do not offer my opinion on which kit is best in public forums.  Email me privately if you want my opinion on this subject.

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Dana danalinscott@yahoo.com
agil3

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Posts: 6
Reply with quote  #6 
Dana or anyone with info on lift pumps. This is my first conversion. I'm purchasing most of the pieces from Gregg at vegpower.com. I'm converting a1981 VW caddy. It will be a 2 tank system, using two 3-port valves, HotFox intank heater, coolant-heated VO filter, ArcticFox inline coolant heater, HOH Veg oil line. Reading a few other posts, I've gotten the idea that running a lift pump on the VO circuit would be beneficial. The Walboro FRB-5 pump seems to be a good unit. According to the specs, the FRB-5 puts out a max pressure of 11psi. Will this pressure hurt my IP? Thank you
danalinscott

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Posts: 934
Reply with quote  #7 

Quote:
Originally Posted by agil3
Dana or anyone with info on lift pumps. This is my first conversion. I'm purchasing most of the pieces from Gregg at vegpower.com. I'm converting a1981 VW caddy. It will be a 2 tank system, using two 3-port valves, HotFox intank heater, coolant-heated VO filter, ArcticFox inline coolant heater, HOH Veg oil line. Reading a few other posts, I've gotten the idea that running a lift pump on the VO circuit would be beneficial. The Walboro FRB-5 pump seems to be a good unit. According to the specs, the FRB-5 puts out a max pressure of 11psi. Will this pressure hurt my IP? Thank you


Your question has been answered HERE please post any further posts on this in that discussion.

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Dana danalinscott@yahoo.com
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