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Through aggressive application of the Miller Cycle, using two-stage turbocharging, medium speed diesel marine and stationary power engines are demonstrating over 30 bar rated power BMEP, and over 50 percent brake thermal efficiency. The objective of this work was to use engine cycle simulation to assess the degree to which the aggressive application of the Miller Cycle could be scaled to displacements and speeds more typical of medium and heavy truck engines. A 9.2 liter six-cylinder diesel engine was modeled. Without increasing the peak cylinder pressure, improved efficiency and increased BMEP was demonstrated. The level of improvement was highly dependent on turbocharger efficiency - perhaps the most difficult parameter to scale from the larger engines. At 1600 rpm, and a combined turbocharger efficiency of 61 percent, the baseline BMEP of 24 bar was increased to over 26 bar, with a two percent fuel consumption improvement.

Turbocharging is an integral part of many internal combustion engine systems. While it has long been a key to diesel engine performance, turbocharging is increasingly seen as an enabler in meeting many of the efficiency and performance requirements of modern automotive gasoline engines. This replay discusses the basic concepts of turbocharging and air flow management of four-stroke engines. It explores the fundamentals of turbocharging, system design features, performance measures, and matching and selection criteria. Topics include spark ignition, diesel engine systems, and the impact of different applications.