Variable Nozzle Turbochargers for Medium-Speed Diesel Engines

Design and application techniques of variable nozzle turbochargers for heavy duty diesel engines have been developed using data collected from a series of tests using an II-liter, 6-cylinder diesel engine.

Test data showed that at 2000 RPM, brake specific fuel consumption (BSFC) is relatively insensitive to changes in the turbocharger nozzle settings, suggesting that the “rated speed” of the engine should be reduced to an area where BSFC could be improved by adjustments in the air-fuel ratio through use of the variable nozzle turbocharger. The data revealed that only about 1/3 of the mechanically available VNT nozzle travel was used, indicating that a more simplified design of the VNT may be possible. The data also showed the importance of knowing the final application of the engine for best matching results.