Now that the system had been tested and shown that it works, it was time to redesign the system using the things I had learned. Plus, it looked like crap and I wanted to improve the asthetics of the system. I yanked all of the old stuff out, laid out the new system, and went to the hardware store to get supplies. I moved the fuel filter to the trunk, reduced the number of hose conections, and increased the length of the hose-in-hose heat exchanger.

To show the system I have created a a diagram which shows the fuel flow. No comments on my art skills. As with the previous system, I used larger fuel hoses than needed to ensure easy flow in cold weather.

For the new system, I removed the electric heaters and went with just a radiator coolant heated system. As before, I used copper for my fuel lines because of the excellent heat transfer properties. Coming from the fuel tank I use a hose-in-hose system to maximize heat transfer. I also wrapped the coolant hoses around the filter to heat it up some too. The fuel return WVO line is also heated by a hose-on-hose system. [Remeber that diesels not only have a fuel supply line but also have a fuel return line that allows the excess pumped fuel to return to the fuel tank. This is unique to diesels, gasoline cars do not have this.]

I have a digital temperature sender immersed inside the fuel line just before the fuel injector pump and it tells me what the fuel temperature is before it enters the engine. This lets me know that the WVO is entering the engine at the necessary temperature. In the previous system I used an electric heater to add additional heat if needed. In this system, I eliminated the need for this by running the hose-in-hose heater as long as possible. It runs all the way from the filter at the WVO fuel tank up to the fuel selector valve. I minimized the areas where the WVO could loose heat and mazimized the length of heat transfer. Now, this system heats better than before, has no electric system, and is much simpler.

Fuel Loops
There are two ways to handle the return fuel line, described below and shown in the diagram.
Closed loop - Advantage- it allows filtered and heated oil to be recycled and sent back to the engine. It reduces the work by the injector pump and keeps the WVO at a hotter temperature. Disadvantage- is that any air that is in the fuel line is trapped and may cause the engine to stall at idle. This is a major problem if your system is not 100% air tight or if you run out of fuel, or change the filter and air gets sucked into the line.
Open loop - Advantage- Air gets purged from the fuel lines. Disadvantage- hot, filtered oil gets dumped into the fuel tank, which requires a larger fuel flow through the filter (compared to closed loop) and the WVO has to be heated more which may result in colder WVO hitting the engine (compared to closed loop). This is not a problem if you have a good injector pump, a high capacity filter assembly (e.g. 40 gallons per hour factory rated), and a excess heat transfer capacity.

The fuel injection pump pumps probably 4 times more fuel than it needs (depending of course on throttle position) which means in an open loop system you have to heat lots of WVO. Open loop and closed loop each have advantages and disadvantages, so I made the system adaptable to both depending on my needs. In this system I have a 3-way valve on the the return fuel line just before the fuel tank which lets me choose whether the system is a open or closed loop. In cases where I have tampered with the fuel lines and have introduced air, I run the system in the open loop mode for a few miles. By this time the air is purged and I switch back to closed loop mode to take advantage of recycling the hot filtered oil.

Installation
I decide to run the coolant/fuel hoses through the car. Running them under the car would expose them to damage from road debris, hitting a rock may cause a hose to burst and dump all my engine coolant on the road. Here are some pictures of the installation.

  Radiator/fuel hoses bunded together	         	Hoses insulated 

Preparing cut through points so      Front floorboard after carpet laid down
sharp metal doesn't damages hoses   

This is what the backseat of my car looked like before I started the conversion. I didn’t want to make too many changes to the car in case the system didn’t work. I figured the easiest way to get the fuel from the trunk to the engine was to run it through the car. I live in an apartment and didn’t have easy access to the bottom of my car.






Now here is what my back seat looks like now. Yes it looks like crap, but I almost never have anybody back there anyway.

To make sense of this I have constructed a diagram which shows the fuel flow.

I used both a radiator water heated system and an electric heated system. I used copper for my fuel lines because of the excellent heat transfer properties. Coming from the fuel tank I use a hose-in-hose system to maximize heat transfer. I also heat the WVO some before it goes into the filter. Then it gets heated more after it leaves the filter. The return WVO line is also heated by a hose-on-hose system. I don’t know if this adds much heat, but it was easy to do.

I have a digital temperature sender immersed inside the fuel line and it tells me what the fuel temperature at the fuel pump is exactly.





The fuel injection pump pumps probably 4 times more fuel than it needs (depending of course on throttle position) which means in an open loop system you have to heat lots of WVO. Open loop is required to get air out of the system (open loop means WVO is returned to fuel tank, closed loop means it gets fed back to the fuel pump). You can see the valves next to the filter which form a three way valve. This allows me to use either an open loop system (back to the fuel tank) or a closed loop system (recyle back to the fuel pump). With this system a closed loop is required to get WVO to 160-180 degree range by recycling previously heated oil. Without this recycling my WVO only gets to 145 degrees even with 200 degree radiator water and the electric heaters.

AC inverter to power my electric heater.
I am running about 280 watts to my heaters. The electric heaters are 120 volt resistance heaters which wrap around the copper fuel line. I have an inverter powering them and a 180 degree thermal switch which turns the current on and off.

This is my Dahl 2 micron filter which I got off of Ebay for a great price. The best thing about this filter is the clear bowl at the bottom. This traps dirt and water before it gets to the filter and since it is clear it is easy to check. According to the manufacturer the filter is rated up to 190 degrees.