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The benefits of adding variable compression ratio (VCR) capability to a Gasoline Turbocharged Direct Injection (GTDI) has been experimentally explored by AVL to quantify the potential efficiency improvements along with other combustion benefits and challenges. The development process is discussed along with key results showing how the combination of VCR, GDI, external cooled EGR and variable cam phasing was optimized to achieve maximum benefit. The concept demonstrates aggressive downsizing capability with BMEP levels above 40 bar BMEP with a two-stage turbocharging system on 95 RON gasoline. The iso-BSFC sweet spot was also improved with reduced BSFC over a broader operating range. The issues of knock, low speed pre-ignition, particulates and sensitivity to octane level and ambient temperature conditions were also investigated and are discussed. Engine level results are shown translated into predicted NEDU vehicle fuel economy improvements.

The development of PM and NOx reduction system with the combination of DOC included DPF and SCR catalyst in addition to the AOC sub-assembly for NH3 slip protection is described. DPF regeneration strategy and manual regeneration functionality are introduced with using ITH, HCI device on the EUI based EGR, VGT 12.3L diesel engine at the CVS full dilution tunnel test bench. With this system, PM and NOx emission regulation for JPNL was satisfied and DPF regeneration process under steady state condition and transient condition (JE05 mode) were successfully fulfilled. Manual regeneration process was also confirmed and HCI control strategy was validated against the heat loss during transient regeneration mode. Presenter Seung-il Moon