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Variable Geometry Turbocharging of a 1.8 DI Automotive Diesel Engine
Published June 16, 1997 by ISATA - Dusseldorf Trade Fair in United Kingdom
Event: ISATA 1997
Variable Geometry Turbocharging (VGT) has, in the past, found limited applications on heavy-duty, "truck-type" diesel engines with the dual objective of improving torque back-up and transient response. Recently, diesel passenger cars have appeared on the market incorporating VGT technology. However, it is now recognized that VGT offers the potential also to improve the emission characteristics relative to engines equipped with conventional waste-gated fixed geometry turbochargers (FGT).
An extensive test program is currently being conducted at the University of Bath on behalf of the Ford Motor Company on a prototype passenger car Direct Injection (DI) diesel engine capable of meeting the proposed European Stage 3 emission legislation with catalyst exhaust gas after treatment. The investigation is aimed at assessing the benefits of VGT over conventional turbochargers in terms of lower fuel consumption and reduced emissions. Steady state tests have been conducted to determine emission and fuel consumption trends at discrete engine operating points as functions of Exhaust Gas Recirculation (EGR) valve position and turbine nozzle vane setting. These tests have shown that up to 19% reduction in part-load NOx is possible (at discrete engine operating points) without compromising fuel consumption.