New emissions regulations and performance requirements imposed on modern diesel engines encourage the development of improved tools for emissions measurements. This study investigated one of the improved tools for NOx emissions measurement. It focused on measurement, comparison and prediction of NOx emissions from heavy-duty diesel engines using two different NOx analyzers. Steady state and transient tests were conducted on six heavy-duty diesel engines and NOx emissions were measured using a conventional Rosemount NOx analyzer and a Cambustion fast response NOx analyzer.Test data obtained...