GOING GREEN

I recently noticed that some heavy military trucks are equipped with “multi-fuel” diesel engines, which to me means Straight Vegetable Oil (SVO) capable. Do you know of any military multi-fuel engines light enough for a pickup or Humvee or are they just for heavy trucks?

I also have interest in converting a HMMWV 6.2L diesel to SVO. I need to determine whether the fuel injection system would tolerate the higher viscosity of SVO. I know using SVO in newer diesels is a bad idea, which is why I am interested in the Mil-spec multi-fuel truck engines. I think bio-diesel may work out of the box with just a fuel filter change on the 6.2L diesel.

We have a reliable supply of bio-diesel here in Oregon due to all of the potatoes being turned into potato chips. One of the chip processors began producing commercial bio-diesel that locals can buy at the pump. That fuel completely changes the smell of my Dodge truck, and neighbors think I’m green. I’m primarily interested in waste vegetable oil but I have not found a reliable method I would trust to get the water out. Would the Mil-spec 6.2/6.5 be a better platform than my 1990 Cummins for alternative fuel experimentation? Greg Woods Portland, OR

The early Dodge Cummins diesels used a rotary, distributor-type fuel injection pump. Its tolerance of bio or alternative fuels would be roughly the

same as the DB2 Stanadyne rotary pump used on the 6.2/6.5. Getting the water out is vital.

Multi-fuel military diesels (including the 6.2/6.5) are designed to run on most petroleum distillates of a similar class to diesel fuel. This would include diesel #1 and #2, Jet A/B, kerosene, B20 bio-diesel and so on. The fuel injection pumps used by the military diesels incorporate hardened components that allow running fuel thinner than #2 diesel fuel. In the civilian market, Stanadyne offered an “Arctic Kit” for their DB2 pumps, which allows running straight #1 or kerosene long-term in extremely cold climates.

The U.S. military has been using bio-diesel blends since at least the early 2000s—mostly B20 (20% bio and 80% petroleum diesel fuel). We like the idea of creating bio-diesel from waste vegetable or animal fat oil, but current economics don’t support diverting food production into commercial fuel production. The biggest problem with waste vegetable oil is that there isn’t enough of it available to have much of an impact.

Quite a few diesel owners have experimented with using straight vegetable oil as a replacement for diesel fuel. A working system usually requires a tank heater to reduce the SVO’S viscosity, and a tank switcher to start/stop the engine on straight #2 diesel fuel. Cold weather operation is another concern, but not everyone lives in areas with extreme cold and snow.

We’d like to see more investigation in the use of waste motor oil, ATF, hydraulic fluid and other waste petroleum products. There’s a huge supply available, and with proper filtering, mixing it with petroleum #2 diesel fuel could allow for a 10-20% reduction in overall fuel cost. More research is needed to determine its long-term effect on engines, fuel injection systems and vehicle emissions. We wouldn’t use a fuel mixture like this in a newer diesel equipped with a DOC (Diesel Oxidation Converter, aka catalytic converter) or DPF (Diesel Particulate Filter), but an earlier diesel would likely do well.