Conversion of F250 Powerstroke 7.3L Diesel to Waste Vegetable Oil
I currently have a 50 gallon Mueller crossed-poly marine fuel tank for my veggie use. I welded together a frame made of 1" square tube to mount the tank within. It is surrounded by 1" rigid Styrofoam insulation on all 4 sides and the bottom. Also, my tank frame has a 2.5" tall, 8' wide opening across the bottom to allow me to still haul a few sheets of plywood, or one layer of 2" thick lumber and use the full length of my bed. The tank frame is mounted down to the bed on each side with Grade 8 5/8" bolts. I am using the stock tank sending unit that came with the tank I also have a hotstick tank heater connected to a 1/2" push-lock hose to the veggie filter.
The veggie filter is a Davco 234+. I ordered it from www.davcotec.com, and it includes the 12V heat option, though I am not sure it really adds much more heat then what the coolant heat already provides. It is installed on the vacuum side of the pump. I had read many concerns about mounting the pump this way, so I did some flow testing with the Aeromotive A1000 pump before I installed them. I ran a 3/4" hose from a bucket of room temp WVO, to a 1/2" alum. tube to the A1000, and then a 3/4" hose back to the bucket. There was no regulator in this test setup, so that the pump should flow as much as it possible could. The filter seemed to flow fine, and the pump ran well without any sign of cavitating. This filter needs to be installed vertically. As this filter is quite large, I was unable to find any place to mount the filter underneath that I was happy with, so I decided to mount it along with the pump in a crossover toolbox. I mounted the relays and fuses for the pump and Davco 12V heat at the same location. I purchased the fuel pump, an Aeromotive A1000, at a local Jegs.
The fuel supply and return are both soft 1/2" alluminum that I purchased Jegs as well. It is coolant heated in a Hose On Hose (HOH) configuration with a rubber coolant line, all ziptied into a bundle, and then wrapped in foam pipe insulation. The returning coolant line (5/8" heater hose) is not run in the HOH bundle, because I believe the coolant returning after running through all the stuff may be colder then the oil in the lines and could actually reduce the efficiency if it was included in the bundle.
The truck runs in stock form until the coolant reaches a certain temp (I have been using appprox 160 F). Then it is safe to turn on the Aeromotive pump. The A1000 is a high pressure, high flow pump and easily pushes the hot WVO with enough pressure to close the diesel checkvalve, forcing it to just continually return through the stock FPR. The A1000 pressurizes the fuel system up to whatever pressure the WVO FPR is set to and then operates the heads in a looped return configuration. My setup is running the pressure at 70 psi at the FPR at rear of the heads; this causes a pressure of about 100 psi in front of the heads due to the high flow of the A1000. When I am ready to shut the truck off, I shut off the A1000 pump, and then open the fast purge valve for about 10-15 seconds. This causes the stock fuel pump to push all of the veg.oil out of the fuel rails, and into the veg. return line. Then I close the purge valve and the truck is again running in stock form. The only thing left to purge would be a very small amount of WVO in the injectors themselves, and should only take a few more seconds. That's it. The truck is purged and ready to shut down in less than 30 seconds.
Here is a picture of where I tapped into the cabin heater supply hose. I just put a tee on the hose and ran the WVO circuit in parallel with the heater core. I did this so that I could attach a ball valve to each leg of the circuit. This is so that I can close the heater core off in the summer, allowing a faster WVO switchover, and so that I can close the WVO circuit off in the event that I ever develop a coolant leak.
I mounted all the gauges and switches into a box I purchased from radio shack. I have an Autometer economy coolant temp gauge (sending unit mounted on coolant output of final H.E.), an Autometer economy Oil temp gauge (sending unit mounted in aluminum junction manifold just before heads), an Autometer digital fuel pressure gauge (sending unit mounted in same aluminum. manifold), and digital fuel tank gauge, using the marine sending unit that came with the tank.
Here are pictures of the gauges in various modes. The first one is shortly after start up (engine was still warm), still running on diesel. Notice the fuel pressure. The second is while running on WVO. Notice the higher fuel pressure, and much higher WVO output temp of 190 F. It does not take more then a few miles to reach this temp, and stays pretty constant. The third is during a quick purge. Notice the extremely low fuel pressure. This is due to the purge valve being open, allowing the diesel to force the WVO out of the heads.
I actually knew virtually nothing about WVO conversions before this project, and learned most of what I needed to design and build this conversion from www.thedieselstop.com and http://biodiesel.infopop.cc.
I used the following vendors to purchase pretty much all of the parts:
Aeromotive pump, Mallory FPR, Aluminum line, Autometer guages, many of the AN fittings: Jegs
Davco 234 Plus: www.davcotec.com
Final Heat Exchanger, checkvalves, 12V purge valve, AN fittings, other misc. www.mcmastercarr.com
Hotstick, Digital fuel gauge, and replacement fleetguard filters for the Davco: www.vegpower.com
Other fittings and miscellaneous supplies came from the local Lowes.