Optimization of Off-highway Engine for TIER-II Emission Norms Using Cost Effective Fuel Injection Equipment

A major task faced by engine manufacturers all over the world is to upgrade running engine designs with least possible modifications to meet next level of emission norms. This saves the precious lead-time and investments. In addition simplicity of design has to be maintained as far as possible while improving emissions. This is possible only by optimal combinations of FIE and engine. This paper describes such a cost effective up-gradation of an engine from US Tier 1 to US Tier 2 in very short time with minimal design changes. This difficult task was achieved by using latest techniques of simulations, measurements and concurrent engineering. For variable speed application it is desirable to retard injection timing as speed decreases, to compensate gain in absolute time. For constant speed application, retardation at part load is required as more weightage is given at part loads for the emission test cycle. The required injection characteristics were achieved by means of stepped plunger. Exhaustive endurance tests validated the modified design. This technology is being implemented on other variants of this engine. Optimum injection timing to meet combustion requirements at different operating conditions and shaping of fuelling curve to meet output demands results in better emissions without affecting other characteristics like fuel consumption, torque and startability.