Initial Considerations

Written by TsTDI

I am writing this guide on behalf of the WVO community as a primary means of searching for relevant, experienced information regarding the use of WVO in diesel engines (specifically the TDI VE rotary engine).

Disclaimer:

This is a guide and by no means a guarantee. There is nothing guaranteed with the use of experimental fuels (Please see Experimental and Alternative Fuels: an overview). This guide is written on behalf of me and my experiences thus far with the use of WVO. My experiences include the use of burning WVO in three different vehicles, two of which are converted with the Greasecar kit. I will discuss each of these further in detail later in this guide.

The Two Tank Conversion Kit

Written by TsTDI

At this point, you are chomping at the bit to start burning WVO and doing so successfully. There are many options out there to decide from, so many that will make your head swim. I will discuss the three approved kits. They are kits that come with all the parts and assemblies for you to install it on your car. Note: I said YOU install on your car. I will stick to Greasecar, Frybrid and Elsbett. I will discuss the advantages/ disadvantages of all three. My experience has only been with the Greasecar kit; however, I know enough to comment on all three and understand the most important aspects of a kit.

The Elsbett Single Tank Kit

Written by TsTDI

FALLACY #1

The kits provided above do not provide the means of burning WVO for the long term. Modifications are a MUST to a TDI engine to ensure the utmost confidence in long term success. This information is not released to you, they run a business, they sell a kit, and it works, but not for the long term.

Coincidentally…..

There are people on this forum and other forums that have burned WVO successfully for over 100k with just a bare minimum kit that I described above. I am amazed by this personally. My thought process on this was as follows, "If I can do more than the minimum that is only giving me a better opportunity at success." I will leave that choice to you, a bare minimum kit and the above directions will get you a car that runs WVO. Personally if I was to go that route, I would have NO confidence in the long term.

IDI vs. DI

Written by TsTDI

Diesel engines have different means of injection and injection pressures that make them widely different from engine to engine. You must understand that IDI engines are less prone to failure compared to DI engines and the reasons why. So whats IDI and DI? IDI stands for indirect injection in which fuel is delivered into a pre-chamber before it reaches the main combustion chamber. Combustion starts in this pre-chamber and eventually reaches the main combustion event. This is beneficial to those who burn WVO because it allows more time for atomization and therefore a better opportunity at a complete burn for a fuel that is slower burning then diesel. IDI engines are based on a fuel/air mixture based off of fast moving air, slow moving fuel in an engine. Thus, the injectors are not as complicated as a TDI’s and can run lower fuel pressures.

Polymerization & ERG

EGR- Exhaust Gas Recirculation- EGR has been a popular emissions device on gasoline engines for a long time but arguably has been a disaster on the diesel engine. Problems caused with EGR equipped on diesels are intake clogging with soot and clogged turbochargers. This results in poor performance and poor fuel economy. The reason why intake clogging occurs is because diesel engines were manufactured from the factory with EGR’s before the introduction of ULSD (ultra low sulfur diesel). Sulfur laden diesel fuel that for the longest time was considered to be a lubricant for a diesels fuel system, causes particulate matter emissions. The easiest way to eliminate this was to take the sulfur out of diesel. Even with the reduction of sulfur in diesel fuel, it still seems that intake clogging continues to be a problem with diesel engines due to particulate matter accumulating over time. Even with ULSD, diesels equipped with EGR’s tend to still have the above listed problems.

Fuel Temperature & Timing

Written by TsTDI

The next friendly adversary on the TDI engine is the fact that engine timing is mapped with fuel temperature. The reason why the TDI engine is so efficient is due to the intricacies of the fuel system. The one component of interest is the fuel temperature sensor. For explanation reasons, let’s assume we are talking strictly of diesel in the next two paragraphs.

Timing is adjusted with hotter and cooler fuels. Upon startup, which should be 100% diesel fuel, the fuel is cold and therefore quite dense. Density will change for liquids under two scenarios, temperature and pressure. The ECU senses the cold fuel, injects less fuel and advances the timing to compensate (you can actually hear this upon startup with slightly higher pitched ticking initially until it goes away). The reason why the ECU injects less fuel is there is a preset injected quantity amount the ECU abides by. To achieve the same mass of fuel to meet actual vs. requested injected quantity, the ECU must inject less. The reason for the advanced timing is because the fuel is denser (cold) and therefore has more mass. A denser fuel is less prone to combust. To combat this lower cetane, (not readily wanting to combust) advancing timing will help combust an inherently denser fuel by allowing more time for the fuel to atomize in the combustion chamber before it is compressed.

Conversion Accessories

Written by TsTDI

EGT Gauge-

I wanted to take the time to explain a further importance of having an EGT gauge on any diesel. Other than finding a critical component of the puzzle that is burning WVO in a TDI, an EGT gauge is a wonderful tool to have on a car because it lets you know what is going on with combustion at all times. I told you before in this guide, when you start off with a car that is in good shape, maintained well and up on all scheduled regular engine maintenance, comparisons can be made when burning WVO. Anything out the ordinary will raise eye brows and therefore, will alert you to a problem long before catastrophe ever occurs.

Maintenance and Operation

Written by TsTDI

There are two compression rings and one oil ring. Obviously the compression rings are on top and the oil ring is below. The oil ring is composed of three parts (2 scrapers and an expander). One scraper is better for when the piston goes down and the other scraper is better for when the piston goes up. The expander is basically a collection point that allows any oil left over to collect and fall through the bottom of the piston. The theory behind piston wall scarring is due to incomplete combustion of WVO in the startup event (signaled by smoking of the exhaust). If there is any residual WVO being attempted to combust at startup, (not enough purge times, not driving long enough on diesel after purging) droplets of WVO may come in contact with cylinder walls. Since the two compression rings have not fully expanded (not at operating temperature), residual WVO seeps below the top compression ring and will coke in a hard carbon form between them. When this happens, the hard carbon form has no where to go except up and down the piston wall and in the process scraping it and damaging the wall severely.

Filtering Oil

Written by TsTDI

Filtering is very important when dealing with waste vegetable oil (WVO). They call it waste oil for a reason. Waste vegetable oil is laden with free fatty acids, bacteria, dirt, debris you name it, its probably there. To get this fuel to acceptable means of burning it without damage to your injection pump, it must be filtered thoroughly. The other aspect that is important is that the WVO can not have water in it. In my experience, we have not had the need to dewater our oil because we know where the oil comes from and our suppliers are good about keeping the lid tight on the barrel that covers the WVO. To ensure that we have filtered our oil well enough, we do a number of things.

Postscript

Written by TsTDI

I hope your head is spinning with all sorts of information you have not known before. The goal of this guide was not to confuse you; however, I wanted to make it blatantly obvious that there is much more to burning WVO than what people think. Although I consider it a hobby, there is a science behind it that allows combustion of vegetable oil to be possible. Understand this guide in its entirety. Every topic, whether confusing or too sophisticated, was written for a reason. I would be happy to answer any of your questions in the future. I want to thank all of those who I included in this thread, especially those who have failed while burning WVO. It is you who allow progress to be made in the world of burning vegetable oils. Thanks for reading and Happy Greasing!