Monday of Memorial Day.

I found myself on a 50' sport fishing boat, anchored, drinking beer and taking in the sun and the passing bikinis. Who would have expected that also on the boat was a senior Cummins Engineer that specialized in fuel system development. We talked, and drank more beer. This is what I gathered from the conversion in respect to WVO as an alternative fuel in diesel engines.

  1. Clean it - Literally the first thing he said was that it needed to be clean of solid contaminants. Obviously the fuel needs to pass through the injectors, but he also pointed out that the fuel is also the lubrication for parts of the fuel delivery system. Abrasive contaminants in the oil will cause scoring in the injector and IP parts leading to a costly repair. Also, generally speaking, newer engines have much smaller injector sizes require higher pressures; they also will be less tolerant to contaminants and alternative fuels.

     

  2. Older Engines – As emission standards have increased the engines have changed to accommodate. In addition to improving combustion with changes to the fuel delivery system; the latest generation engines starting in '08 now have “after treatment devises”. You can think of AFDs a similar to catalytic converters of gasolene engines. One exception, is that the AFD will collect carbon deposits and the engine computer will regularly need to “re-gen” the AFD by injecting fuel into the exhaust to burn off/ clean the AFD. Alternative fuels in this type of system will almost certainly be full of problems.

     

  3. Load and Duty Cycle – This is where things got interesting for me as my primary concern with WVO is coking of the combustion chamber, piston ring failure, cylinder scoring ect. My understanding is that by starting on diesel and only using WVO in a hot engine. I am avoiding the excessive carbon deposits by avoiding the incomplete combustion associated with starting on WVO. However, this appears to be only part of the picture. Clearly WVO has more of a tendency to leave carbon deposits than diesel but even diesel can produce the same problems when associated with low engine temperatures. The other side of the equation is that high engine temperatures correct the problem. Similar to how new diesel engines burn off the AFD of carbon; high load/high engine temperatures will burn off carbon deposits in the engine. Also interesting is that this can be accomplished in as little as 5minutes of high load/temperature.

So, what does this all mean to you and I?

Mostly, business as usual; clean oil is still critical to long term WVO success. New engines 04-07 may be more difficult to convert to use waste oils, 08+ engines may not even be possible to convert to alternative fuels. The real news here is that even though you have an expensive automated two tank conversion; if you drive like a grandmother; you could still be causing damage to your engine. The other side to that is that if you “drive it like you stole it” you may be able to get away with no conversion at all. Assuming that you can start on whatever blend you have in the tank.

I still recommend a dedicated fuel system for WVO; lets face it, the probability of something plugging up, failing or just going wrong is very high. Do the conversion right and you will not reduce the reliability of the vehicle for cold starting or long trips. However, everyone running WVO must find a way to “burn out” the engine at least every couple months. Trucks: pull something heavy up a hill, down the highway, sustained full power is what you are looking for. Cars: its rally time, drive it like you stole it, hard on the throttle, hard on the breaks. Be safe, have fun, and know that you are doing your engine good.