A5INKY
Vendor , w/Business number
I alluded to creating this thread over a month ago in another alt fuel thread on this forum. Life is what happens while we were making other plans and I set it aside for awhile, here it finally is. This is a basic summary of my experience in developing and using a two-tank WVO fuel system in my 2006 Jetta TDI with a BRM Pumpe Duse engine.
Warning! This is not a short tale but I will try to keep it concise. I have decided to discontinue WVO use in my car for the reasons I will show. I don’t care if you agree or not with my methods or conclusions. My only wish is to share my experience and hopefully contribute to the ‘pool of knowledge’. So, if you are interested enough to spend the time - crack open a beer, sit back and off we go.
Some Background
I’ll start by qualifying myself. I grew up in the workshop working on automotive projects and the racing motorcycles on which I competed. I have built and modified all kinds of gasser engines two and four stroke. Professionally I have had several distinct careers in my life: R&D project engineering in two different industries, owned an auto repair shop where I earned ASE Master Tech certification and now in $ales management for an industrial/institutional chemical manufacturer. With my considerable experience in spark ignition engines, this TDI is my first foray in to the wonderful world of diesel.
I chose a TDI because of the classic reasons. I drive a tremendous number of miles for work and was interested in maintaining comfort while reducing expense. I am quite sustainably minded, thinking of myself as a pragmatic environmentalist. That said, I had my eye on WVO fuel when I bought the car used with 15K miles on the clock (I assume it was a lease return).
I started my WVO hobby by doing research on the interwebs. I read everything I could find for literally months. I saw everything from the horror stories to the testimony of the true believers to the vendor sites and forums. I formed the opinion that the folks pursuing WVO were typically long on ideals and short on technical ability. The failures usually appeared the direct result of obvious (to me anyway) negligence.
My average commute each day is around 100 miles each way, perfect for VO use. With my driving needs, technical/development background and need for a hobby at that time, I decided to go for it. I felt I had the issues covered or could solve them along the way.
System Design and Development
The search for a “kit” that would satisfy my design requirements resulted in a dead end. The kits were all lacking something key. True, I could buy one anyway and make all the needed changes, but in the end I decided to start from scratch. The first iteration of my system included:
At this point I started wondering about keeping the VO tank so hot. Much more research led me to learning about VO polymerization and the contributing factors. I learned that combining heat, oxygen and a catalyst like copper or ferric metals would make poly in short order. I had strategically passed on the Greasecar system with its copper coil in-tank heat exchanger (what I refer to as a “poly-generator”). My tank had nothing but stainless and aluminum in it, but I decided to reduce the tank heat anyway. I did this first by using a manual 3-way fuel selector valve mounted near the tank to allow two selectable fuel return modes, either back to the tank (for bleeding air after a filter change) or a running mode that looped the return back to the VO lift pump inlet. This reduced heat in the tank to only that supplied by the Hotfox. I then decided it was still way more heat than I needed and located a universal heater control valve on eBay that would allow me to meter coolant to the Hotfox while bypassing any unneeded coolant straight back to the engine. I quickly learned that in the summer, the tank needed no heat at all.
For more safety margin I increased my coolant temp trigger for switching to 180F and increased shutdown run time to 1:45. Even with that I got in the habit of manually triggering purge a few miles from my destination. I typically was seeing VO temps out of the tandem pump of 195-225F. UOAs were showing a little elevation of Fe but no sign of any VO.
All seemed well for a long time until a mysterious oil leak developed under the car. I took the HOH down and found the leak to be a pin-hole in the aluminum line, strange. I fixed it with a compression coupler fitting and put it back together thinking it a fluke. A month later the leak was back. This time it was a number of pinholes, ***? My theory is that over time the oil, which is mildly acidic, ate through the thin annealed aluminum fuel line. At this point I made a new HOH assembly using PEX for both the fuel and coolant lines under the car, insulated them and solved the leaks. Noticing that the flexible VO lines were getting spongy I found the biofuel compatible “superfuel” hose and updated all the hoses in the system. I also ditched the worm gear type hose clamps in favor of spring clamps on the coolant hoses and “fuel injection” hose clamps for the fuel lines.
Even though my WVO filters were lasting about 10K miles each, I didn’t like waiting for the filter to plug to change it. I installed an absolute pressure transducer from VO Control Systems in the fuel filter outlet but before the pump. Wired into the VO Controller, fuel suction vacuum is monitored and will shut the VO system down when it hit a preset value. No more waiting for power loss to know the filter needs changed.
I didn’t like how air had to pass through the tandem pump and cylinder head before being purged to the VO tank. In developing a different strategy for purging air I also saw a way to pre-heat the VO in the system before switchover. I added a 3rd solenoid fuel valve in the engine bay that had a normal mode of bypassing the usual supply side solenoid. By wiring it to switch with the supply solenoid and taking VO lift pump control away from the VO Controller (to a manual switch on the dash) the system would circulate fuel through the lift pump/HOH/FPHE during the car warm up, pre-heating the fuel. To protect the VO lift pump, I added a temp switch to the coolant line that would not turn on the VO pump until coolant reached 150F (this detail was likely overkill). Now, to purge air after a filter change I would simply switch the manual 3-way valve in the trunk and the pre-heat loop would purge all the air directly to the VO tank prior to switchover. Before the next start-up I would then switch it back to the looped return (run) mode position and have a nice coolant heated VO fuel preheat system that raised initial VO temps about 20F prior to switchover.
When I initially mounted my tank I thought I could keep it clean enough that spill would not be an issue. Even as careful as I am always am, sh!te happens and I had spilled oil a few times. With my tank tray construction materials and design it was impossible to completely clean it up and I eventually got sick of the residual smell. To solve the problem I built a custom steel secondary containment tray.
The tray would hold the filter assembly, the VO lift pump and the tank on rubber mounts about ¾” above the bottom with a drain tube to outside the car. Any spills would be contained (or if big enough) drained to the ground. Clean-up would also be easy and complete. Of course in the months since this was made I have not spilled a drop.
Warning! This is not a short tale but I will try to keep it concise. I have decided to discontinue WVO use in my car for the reasons I will show. I don’t care if you agree or not with my methods or conclusions. My only wish is to share my experience and hopefully contribute to the ‘pool of knowledge’. So, if you are interested enough to spend the time - crack open a beer, sit back and off we go.
Some Background
I’ll start by qualifying myself. I grew up in the workshop working on automotive projects and the racing motorcycles on which I competed. I have built and modified all kinds of gasser engines two and four stroke. Professionally I have had several distinct careers in my life: R&D project engineering in two different industries, owned an auto repair shop where I earned ASE Master Tech certification and now in $ales management for an industrial/institutional chemical manufacturer. With my considerable experience in spark ignition engines, this TDI is my first foray in to the wonderful world of diesel.
I chose a TDI because of the classic reasons. I drive a tremendous number of miles for work and was interested in maintaining comfort while reducing expense. I am quite sustainably minded, thinking of myself as a pragmatic environmentalist. That said, I had my eye on WVO fuel when I bought the car used with 15K miles on the clock (I assume it was a lease return).
I started my WVO hobby by doing research on the interwebs. I read everything I could find for literally months. I saw everything from the horror stories to the testimony of the true believers to the vendor sites and forums. I formed the opinion that the folks pursuing WVO were typically long on ideals and short on technical ability. The failures usually appeared the direct result of obvious (to me anyway) negligence.
My average commute each day is around 100 miles each way, perfect for VO use. With my driving needs, technical/development background and need for a hobby at that time, I decided to go for it. I felt I had the issues covered or could solve them along the way.
System Design and Development
The search for a “kit” that would satisfy my design requirements resulted in a dead end. The kits were all lacking something key. True, I could buy one anyway and make all the needed changes, but in the end I decided to start from scratch. The first iteration of my system included:
- 14.5 Gal aluminum fuel tank from RCI with Hotfox pick-up and an ISS fuel sender the tank/filter/pump was mounted in the trunk on the driver side to still have the 60% side of the rear seat operable. It was held in place by a spiffy wooden tray covered with speaker carpet (looked nearly OEM nice). With careful tank placement and tray construction I maintained access to the spare tire.
- Ramco coolant heated fuel filter from Plantdrive, 2-3 micron filtering
- Walboro diaphragm fuel pump mounted near the tank and pulling WVO through the filter.
- HOH assembly using aluminum line from Summit Racing and 5/8 heater hose. This was insulated and run underneath the car to the engine bay.
- FPHE from Plantdrive then on to a two solenoid valve system to allow delayed switching to minimize fuel mixing. This was all mounted under the hood to minimize distance to the tandem pump.
- Control came from a VO Controller wired per the diagrams provided. The goal was to make it as automatic as possible but protect the engine from ‘improper’ WVO use.
- VO was plumbed to return to its tank similar to OEM system.
At this point I started wondering about keeping the VO tank so hot. Much more research led me to learning about VO polymerization and the contributing factors. I learned that combining heat, oxygen and a catalyst like copper or ferric metals would make poly in short order. I had strategically passed on the Greasecar system with its copper coil in-tank heat exchanger (what I refer to as a “poly-generator”). My tank had nothing but stainless and aluminum in it, but I decided to reduce the tank heat anyway. I did this first by using a manual 3-way fuel selector valve mounted near the tank to allow two selectable fuel return modes, either back to the tank (for bleeding air after a filter change) or a running mode that looped the return back to the VO lift pump inlet. This reduced heat in the tank to only that supplied by the Hotfox. I then decided it was still way more heat than I needed and located a universal heater control valve on eBay that would allow me to meter coolant to the Hotfox while bypassing any unneeded coolant straight back to the engine. I quickly learned that in the summer, the tank needed no heat at all.
For more safety margin I increased my coolant temp trigger for switching to 180F and increased shutdown run time to 1:45. Even with that I got in the habit of manually triggering purge a few miles from my destination. I typically was seeing VO temps out of the tandem pump of 195-225F. UOAs were showing a little elevation of Fe but no sign of any VO.
All seemed well for a long time until a mysterious oil leak developed under the car. I took the HOH down and found the leak to be a pin-hole in the aluminum line, strange. I fixed it with a compression coupler fitting and put it back together thinking it a fluke. A month later the leak was back. This time it was a number of pinholes, ***? My theory is that over time the oil, which is mildly acidic, ate through the thin annealed aluminum fuel line. At this point I made a new HOH assembly using PEX for both the fuel and coolant lines under the car, insulated them and solved the leaks. Noticing that the flexible VO lines were getting spongy I found the biofuel compatible “superfuel” hose and updated all the hoses in the system. I also ditched the worm gear type hose clamps in favor of spring clamps on the coolant hoses and “fuel injection” hose clamps for the fuel lines.
Even though my WVO filters were lasting about 10K miles each, I didn’t like waiting for the filter to plug to change it. I installed an absolute pressure transducer from VO Control Systems in the fuel filter outlet but before the pump. Wired into the VO Controller, fuel suction vacuum is monitored and will shut the VO system down when it hit a preset value. No more waiting for power loss to know the filter needs changed.
I didn’t like how air had to pass through the tandem pump and cylinder head before being purged to the VO tank. In developing a different strategy for purging air I also saw a way to pre-heat the VO in the system before switchover. I added a 3rd solenoid fuel valve in the engine bay that had a normal mode of bypassing the usual supply side solenoid. By wiring it to switch with the supply solenoid and taking VO lift pump control away from the VO Controller (to a manual switch on the dash) the system would circulate fuel through the lift pump/HOH/FPHE during the car warm up, pre-heating the fuel. To protect the VO lift pump, I added a temp switch to the coolant line that would not turn on the VO pump until coolant reached 150F (this detail was likely overkill). Now, to purge air after a filter change I would simply switch the manual 3-way valve in the trunk and the pre-heat loop would purge all the air directly to the VO tank prior to switchover. Before the next start-up I would then switch it back to the looped return (run) mode position and have a nice coolant heated VO fuel preheat system that raised initial VO temps about 20F prior to switchover.
When I initially mounted my tank I thought I could keep it clean enough that spill would not be an issue. Even as careful as I am always am, sh!te happens and I had spilled oil a few times. With my tank tray construction materials and design it was impossible to completely clean it up and I eventually got sick of the residual smell. To solve the problem I built a custom steel secondary containment tray.
The tray would hold the filter assembly, the VO lift pump and the tank on rubber mounts about ¾” above the bottom with a drain tube to outside the car. Any spills would be contained (or if big enough) drained to the ground. Clean-up would also be easy and complete. Of course in the months since this was made I have not spilled a drop.
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