A 12.9 L heavy duty compression ignition engine was tested with strategies for dual fuel optimization. The effects of varied intake manifold pressure as well as split-injection strategies at a load of 5 bar BMEP and 85 PES were observed. These results were used to allow testing of split-injection strategies at a higher load of 10 bar BMEP at 70 PES that were void of MPRR above 2000 kPa/CAD. The split-injection strategies at 5 bar BMEP showed that lower BSNOx can be achieved with minimal drop in FCE. Varying intake manifold pressure revealed that combustion occurs earlier in a cycle with increasing intake manifold pressure and indirectly increasing FCE. A load of 10 bar BMEP at 70 PES should only use split-injection strategy to maintain load without high MPRR as efficiency drops with dependency on the second injection.