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Currently, 80% of European diesel passenger cars are turbocharged and as emission standards become more stringent exhaust gas recirculation (EGR) will be the primary means of suppressing oxides of nitrogen (NOx). The lighter the load the greater will be the combustion tolerance to increased EGR flow rates and hence increased NOx suppression. Automotive diesel engines using wastegated turbochargers cannot recirculate above 50% EGR without some sort of “added” device or system, which is able to displace the inlet fresh air charge. This has been demonstrated by throttling the diesel intake to reduce the fresh air inlet manifold pressure so allowing more EGR flow by virtue of a higher exhaust-side pressure due the effects of the turbocharger. The method reported here investigates a different approach to increasing the EGR rates by replacing a fixed geometry turbocharger (FGT) with a variable geometry turbocharger, (VGT).

Effectiveness of flow through catalytic diesel particulate aftertreatment devices in reducing particulate emissions is investigated on Ford's 1360 kg (3000 lb.) Sierra 1.8L Turbo-Diesel passenger car. Flow-through monolith type EAO reference catalyst and AC Rochester diesel catalyst are evaluated using Phillip's Control No. 2 diesel fuel, low sulfur (0.05% S) and ultra-low sulfur (0.001% S) diesel fuels. Comparisons are made with baseline exhaust emissions for FTP75 and Highway chassis dynamometer test procedures. Effects of catalyst aging of 320, 1610 and 6450 km (200, 1000 and 4000 miles) are examined. Results, based on 6450 km (4000 mile) limited durability, show that a ceramic monolith substrate of 400 cells per square inch (cpsi) with AC Rochester catalyst is capable of reducing particulate as well as HC and CO emissions to well below the 1994 Government mandated emission requirements with low (0.05% S) and ultra low (0.001% S) sulfur fuel.