[Diesel_Dave]

Originally Posted by mechman600

To throw a wrench in the discussion, I found a biodiesel vs diesel emissions chart. It kind of goes against what I thought about biodiesel:
http://www.biodiesel.org/docs/ffs-ba...fact-sheet.pdf

That comparison was done with all pre-1997 engines. It's really unfair to try to say that the fuel itself makes emissions go up or down by a certain percentage--especially with all the new electronic controls and aftertreatment--it's tough to know how the controls respond. In my experience, most of the "modern" (EGR, common rail, etc.) diesels have larger NOx increases and larger PM decreases than the older diesels.

It all depends on how you run the engine and how the controls work. When I was in grad school I made a controls algorithm that sensed biodiesel via an O2 sensor and then modified the control strategy to keep engine-out NOx, PM, & efficiency as good or better than conventional diesel (with a 2007 Cummins 6.7L):

http://watch.discoverychannel.ca/dai...11/#clip405284