Plantoil/diesel conversion basics
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danalinscott

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(Under construction).


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Dana danalinscott@yahoo.com
cgself

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Dana,

I have an '84 F250 that I'm itching to convert.  I've been asking how to use one of the stock tanks and selector switch, but so far everyone tells me to put in a third tank and another switch.  Any idea when you'll have more info on this?
danalinscott

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Quote:
Originally Posted by cgself
Dana,

I have an '84 F250 that I'm itching to convert.  I've been asking how to use one of the stock tanks and selector switch, but so far everyone tells me to put in a third tank and another switch.  Any idea when you'll have more info on this?

In order to use one of the existing fuel tanks It must usually be removed, the interior cleaned of the dirty wax that often accumulates with long term diesel use, and a  1" NPT port must be brazed or welded in to allow a horizontal probe type heated fuel pickup to be installed. It is also smart to have a similar port installed at the low point of the tank to allow for draining it easily later.

The stock 6 port valve can be used if relocated to the engine bay but the configurations available are limited with a single six port valve and most of the heat added to the VO must be added "downstream" of stock Pollack valves as they are not designed for long term operation at temps over 120­°F. If you use HOH heated fuel line leading up to the valve this should not be a problem.

Before you begin to convert an older engine the first step is to determine how worn it is. A compression and leak-down test is the best way to do this cheaply.

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LarsNelson

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I have never done any brazing on a diesel tank. are the precautions the same as with a gas tank?
Does one use black iron 1" flanges?
What is the horizontal probe/tank heater?

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Lars Nelson
1980 300SD 25k miles on80/20 WVO/Jet A blend, Fatty injection line heaters
25k more with a DIY two tank system.
jwt1954

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Converting 94 ford f-250 , 2 tank. 1. is there diagram for this diesel 7.3 liter? Wiring n piping diagram?  Ist. time dummy


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danalinscott

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Quote:
Originally Posted by LarsNelson
I have never done any brazing on a diesel tank. are the precautions the same as with a gas tank?
Does one use black iron 1" flanges?
What is the horizontal probe/tank heater?

The tank heater referred to is a HotRod (A DIY unit that is about 1/5 the cost of those available from component vendors) and the port usually used is 1/2 of a 1" black iron coupling.

Quote:
Converting 94 ford f-250 , 2 tank. 1. is there diagram for this diesel 7.3 liter? Wiring n piping diagram?  Ist. time dummy
 

We all began knowing next to nothing...your questions are not dumb by any measure. I don't think there is a wiring and plumbing diagram specifically for the 94 F250 7.3 liter engine. I am willing to help you put one together though (once I catch up with the pile of work that accumulated at the office while I was away for 3 weeks). I suggest that you look over the plumbing configurations at: http://www.websitetoolbox.com/mb/voconversionbasics?forum=57553 to begin. This will give you a better idea of the configuration that is best for your conversion. Wiring will depend on that so comes second. Post here when you are ready to proceed.

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Dana danalinscott@yahoo.com
Taylor

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I am at a similar point as jwt1954 is. Maybe I can tag along as you educate him on his conversion. My truck is a 1991 F250, 7.3L. I understand the basics... I know I need to get plans from you, for the "HOTROD" and "simple hand pump dewater and filter" plans. 
I am full of questions, maybe you could answer one at a time, but I'll put down the major ones.

What exactly is the 6-port valve? If I move it forward how will that help quicker purge times. How will I create a two filter system, would it be a filter on the VO line? Where will I get the voltage for the injector heaters? Should I take the tank to a metal shop for the brazing on the 1" NPT? Also couldn't I have all return lines dump into the VO tank, so the diesel would stay clean?

Thank you for your help. 
danalinscott

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Quote:
I know I need to get plans from you, for the "HOTROD" and "simple hand pump dewater and filter" plans.


There are actually several options other than those now.

Quote:
What exactly is the 6-port valve?


Good question..and one that brought to my attention the fact that a good description of their function is not posted yet. I'll remedy that now.

Ok..here's the definition (and link to more info) I jut posted in the Terms and Acronyms - Terms section.

Remote fuel valve/solenoid valve - An electrically actuated valve that allows changing from one tank of fuel to another or diversion of fuel from one or more plumbing circuit(s) to another. The most common remote fuel valves used in VO conversion are 3 and 6 port valves.  A three port valve diverts fuel from one line to two others (one or the other)..and a 6 port diverts fuel from two lines to four others (two at a time).

Quote:
If I move it forward how will that help quicker purge times.


The fuel supply line from the six port valve to the filter or IP is full of VO whenever you decide to purge it (with diesel fuel). The longer it is the more VO that must be used or pushed out of the line..through the IP before diesel fuel reaches it and flows to the injectors. At that point the purge is complete. so the closer to the IP the valve is the less VO must be purged and the quicker it happens.

Quote:
How will I create a two filter system, would it be a filter on the VO line?


The existing stock filter usually continues to be used for diesel fuel but a second filter and fuel circuit is added for VO fuel.  There are a lot of options and opinions on which configuration is the best. And best for one engine, budget, or main vehicle/engine purpose varies. To even provide my own opinion on that I need to know if what your prime concern is with the conversion and how it will be used mainly. Long over the road hauls or relatively short trips.

Quote:
Where will I get the voltage for the injector heaters? 
A wire that is only "hot" when the ignition is on is located with a simple probe light and this is tapped into for the power to the relay and ILHs.

Quote:
Should I take the tank to a metal shop for the brazing on the 1" NPT?
Unless you have the skill and equipment to do it yourself or are lucky enough to have a friend that does you don't have many (if any) other options I can think of.

Quote:
couldn't I have all return lines dump into the VO tank, so the diesel would stay clean?


Yes...many do this and simply add a manual three port valve that allows them to switch the return to the diesel tank if they are ever forced to run for an extended time on diesel.







 

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Dana danalinscott@yahoo.com
Taylor

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Alright. Well specifically I will be doing a lot of short trips. And...

Quote:

There are actually several options other than those now.


So can I get info on assembling one of these options.

What would you advise my next move to be, should I start buying parts...

Thanks


danalinscott

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Quote:
Originally Posted by Taylor
Alright. Well specifically I will be doing a lot of short trips. And...

Quote:

There are actually several options other than those now.


So can I get info on assembling one of these options.

What would you advise my next move to be, should I start buying parts...

Thanks



My advice at this time is to consider if the risk will outweigh the likely benefit. I suggest this because diesels are poorly suited to short trips if your goals include normal engine longevity. And using a VO converted diesel for short trips is even worse.  Specifically I suggest that you figure out how much replacing the engine will cost when the piston rings coke up (which tends to happen when a vo converted diesel is used for short trips) and if the fuel costs you avoid by converting to VO will be more than that at around 30-500K and if so by how much?

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Dana danalinscott@yahoo.com
Taylor

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I think because of the coking that you speak of I may start looking into the manufacturing of biodiesel. Do you have a thread for this discussion?

Taylor

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Reply with quote  #12 
But on second thought what is the definition of short trips? My driving consists of a mix of some very long trips, with a good amount of shorter ones. Do longer periods of driving reduce coking because of so many more strokes by the pistons, or is strictly related to there not being high enough cylinder wall heat? Also I live in a warm climate, so wouldn't a good system heat VO up to the proper temp faster, allowing for shorter trips?

Thank you Dana
danalinscott

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Piston/ring/land/groove coking is explained in detail at: http://www.websitetoolbox.com/tool/post/voconversionbasics/vpost?id=1644578 

It is mainly caused by using VO fuel in an engine not up to operating temperature.

Short trips would be defined IMO as trips where the engine is unable to come up to full operating temp prior to VO being switched to for a significant amount of time before it must be purged. Those who use VO fuel in such situations tend to "cheat" more and more by switching to VO fuel a bit early and back to diesel a bit late (for purging) and the more one "cheats" the quicker ring/land/groove coking progresses.


Quote:
Originally Posted by Taylor
But on second thought what is the definition of short trips? My driving consists of a mix of some very long trips, with a good amount of shorter ones. Do longer periods of driving reduce coking because of so many more strokes by the pistons, or is strictly related to there not being high enough cylinder wall heat? Also I live in a warm climate, so wouldn't a good system heat VO up to the proper temp faster, allowing for shorter trips?

Thank you Dana


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Dana danalinscott@yahoo.com
Taylor

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Reply with quote  #14 
I understand how I can order the directions to the HOTROD, but I've heard you discuss other options that are newer. If I wanted to order directions from you for one of those, how would I go about that.

Thanks
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