I did a quick google and found this web page.
http://www.cytoculture.com/Biodiesel...%20PERFORMANCE


Here is a quick quote from this web site.
In the Volvo marine diesel engine study in Tennessee (110-HP, 2.39 L, 4-cylinder, direct injection engine), a tractor dynamometer was used to measure power outputs under selected loads through an engine-mounted reverse drive gear. Exhaust emissions were also tested along with fuel consumption tests under various loads. The conclusions of these tests were that power produced from 100% soy methyl ester Biodiesel was from 2 to 7 percent less than produced from petrodiesel, depending on the load-speed point. However, at or near maximum throttle (3,800 rpm), the two fuels performed the same. Interestingly, at the lowest engine speed (1855 rpm) at full throttle under heavier load, there was a 13% increase in power with Biodiesel as compared to petrodiesel.

The Tennessee study indicated that using 100% Biodiesel in marine direct-injection diesel engines, with design and construction similar to the Volvo test engine, could be recommended without any significant, noticeable differences in operation, power performance and fuel usage.

In the 1998 study at the Southwest Research Institute on Biodiesel effects on diesel engine performance, engine power in the 1997 Cummings truck engine operating on the B-20 blend was at 98.5% of the power attained with low sulfur No. 2 diesel. At 100% Biodiesel, the engine generated 92% of the power. For a Detroit Diesel truck engine (1997), the power was 98% with the B-20 and 92% with the neat Biodiesel.