> > Any of which can be replaced on an as needed basis. Terry's mechanic > > should be a little more specific with him, rather than issuing a > > sweeping and perhaps unsupported statement.
Perhaps I can shed some light on this topic, as I am an engineer at Cummins Inc, and work in Fuel System Development. Officially, Cummins supports Biodiesel blends up to B5 or 5% Biodiesel. There are several concerns the company has with higher ratio blends. There are three major areas of concerns that the company has. These are mostly commercial concerns which will be evident as I explain them any of which an individual could deal with by being aware and careful about what they put into their tank. First, while biodiesel is touted as being cleaner, there are some caveats. While the particulate emissions (the ones you can see) are considerably improved with biodiesel, the NOx emmission will increase and the higher the biodiesel ratio the higher the NOx increases. Up to B5 the increase will not likely move the engine's NOx emissions beyond the federal limit, but B20 and higher will likely move the NOx emissions "outside of the box". Since the US tends to hold the manufacturers repsonsible for the emissions of the engines instead of the users the company must maintain a strict policy against recommending or accepting fuels that will violate the regulations. Second, biodiesel has a lower heating value than Petro diesel, therefore the higher the biodiesel blend the lower the available power from the engine. Most vehicles with B5.9 diesel are substantially overpowered so the driver may not notice the 2% loss of power with a B5 blend, but it will become more noticeable as the ratio is increased. As I said many of the vehicles, especially pickups are overpowered for the job they do, so you it would likely not be bothered unless you are street racing or pulling a large (heavy) trailer through the mountains. But once again as a company Cummins is in the position that if the sell a 305 Hp engine and the customers tend to expect to get 305 Hp regardless of what fuel they chose to put in the tank. The third and more serious concern for us homegrown biodieselers, in my opinion, is water. Most tanks collect water, many vehicles are equipped with water separation filters to protect the fuel system components. The problem is the biodiesel has a higher affinity for water than petrol diesel, so the biodiesel is going to carry the water out of the tank. Furthermore, the water separators that are normally used will NOT extract the water from biodiesel so the water gets carried into the fuel system. Most modern fuel systems are very sensitive to water. The engine will run initially but the internal fuel system components will quickly corrode which will lead to a fuel system failure, and usually an expensive one. The company is also concerned about the quality of the biodiesel coming on the market. They have a wide variety from some very high quality to some very poor quality and currently there are no recognized quality standard that the commercial producers are going by. There are other concerns with blending biodiesel with the coming Ultra Low Sulfur Diesel (ULSD). It has a few challenges to overcome but I will not go into the details here. With all that said, my personal observation (not the view of Cummins) is that if you pay attention to what you are putting in your tank qaulity wise. You make sure that it is dry. Then you should not have any problems with the fuel system of the age mentioned. The timing does not need to be changed in order for the engine run, however you will be producing more NOx than you were with petrodiesel. You will likely see degradation of non metal lines in the fuel system and you have to replace all of them at some point. Return lines are probably the first ones you will notice. I believe most vehicles run steel lines for the supply lines from the tank to the engine. I am brewing my own biodiesel and running it in my 94 Cummins 5.9L diesel and I intend to eventually run on straight biodiesel. I know the risks and will watch things carefully. I hope this helps Doug _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
