Tier 4 for large bore

Engineers show that a pre-turbine aftertreatment system offers clear and distinct benefits in terms of compact, cost-effective emissions reductions.

Tier 4 emissions legislation is the clear inspiration for widespread adoption of exhaust aftertreatment in off-highway applications. Large bore engine manufacturers are faced with the significant challenge of packaging a multitude of catalyst technologies in essentially the same design envelope as their pre-Tier 4 manifestations, while contending with the fuel-consumption consequences of the increased backpressure, as well as the incremental cost and weight associated with the aftertreatment equipment.

Aftertreatment is a well-accepted enabler for reduction of pollutant emissions beyond the exhaust manifold. Unfortunately, the reality of aftertreatment is that it aggravates exhaust system restriction, and often involves the use of additional reductants such as diesel exhaust fluid (aqueous urea), or fuel, to promote catalytic effects. A direct consequence is an inevitable increase in fuel consumption. Powertrain engineers must minimize this increase in fuel consumption, as circumventing it is simply not possible, say researchers from FEV and Emitec.