Patent ID: 7165400

Claim:
A method for reducing emissions from a turbocharged locomotive diesel engine while maintaining engine performance, said method comprising: providing a plurality of cylinders in said engine, each cylinder having a cylinder head, pistons within the cylinders each having a piston crown and moving to a position adjacent to the cylinder head for compressing gas in the cylinder for combustion; providing a turbocharger for supplying air under pressure to the cylinders, with the turbocharger being driven in part by a flow of exhaust gases from the engine; providing a fuel injection system for injecting fuel into the cylinders; retarding the start of fuel injection in each combustion cycle, to reduce the level of nitrogen oxides in the exhaust gas, with said retarded injection timing also resulting in a reduction in thermal efficiency; increasing compression ratio in each cylinder to 17.4, thereby compensating for said reduction in thermal efficiency, with said increased compression ratio also resulting in a reduced exhaust gas energy level and a resultant decrease in turbocharger speed; and restricting the turbocharger inlet to the flow of exhaust gas to the turbocharger, by reducing turbocharger nozzle ring flow area to 25.4 square inches to increase the exhaust gas flow velocity to maintain said turbocharger speed and boost level of the air under pressure to the cylinders, thereby compensating for said reduction in exhaust gas energy level.