Renewable fuels are promising solutions to replace conventional fossil fuels across heavy transportation, as they are relatively clean (both at the production stage as well as in end use). The proposed experimental research will study one pathway for introducing renewable fuel into an existing heavy duty diesel engine. The experiments will involve using a much smaller amount of diesel to initiate power generation from the main renewable fuel, which will be injected into the engine separately of the diesel. Such an engine will still be capable of operating effectively on conventional diesel when renewable fuels are not available. The goal is to understand the detailed thermodynamics involved and to measure the efficiency and detailed emissions of the engine under a wide variety of operating conditions.