Mattson, J., Mangus, M., and Depcik, C., "Efficiency and Emissions Mapping for a Single-Cylinder, Direct Injected Compression Ignition Engine," SAE Technical Paper 2014-01-1242, 2014, doi:10.4271/2014-01-1242.
A timing sweep to correlate the location of Maximum Brake Torque (MBT) was completed on a single-cylinder, direct injected compression ignition engine that was recently upgraded to a high-pressure rail injection system for better engine control. This sweep included emissions monitoring for carbon dioxide, carbon monoxide, particulate matter, hydrocarbons, and oxides of nitrogen for the calibration of a heat release model, as well as the opportunity to relate MBT timing to brake-specific emissions production. The result of this timing sweep was a relatively linear correlation between injection delay and peak pressure timing. In addition, a number of other MBT timing methodologies were tested indicating their applicability for immediate feedback upon engine testing, particularly mass fraction burned correlations. Emissions were either strongly correlated to MBT timing (with emissions being minimized in the vicinity of MBT), or were completely independent of MBT. In addition, the end of the MBT timing envelope was linked to increased fuel consumption, as well as a rise in aromatic hydrocarbon emissions. Ideal fuel economy with lowered NOx and PM emissions can be achieved for timings just after MBT, but will lead to production of hydrocarbon emissions that present difficulties to catalysis.