Downsizing and downspeeding are two efficient strategies to reduce vehicles CO2 emission, provided that high BMEP can be achieved at any engine speed under clean, safe, stable and efficient combustion. With a 6:1 minimum compression ratio, the MCE-5 VCRi achieves 40 bar peak BMEP at 1200 rpm with no irregular combustion. If peak BMEP is maintained below 35 bar, fuel enrichment is no longer necessary. When running at part loads, the engine operates at high compression ratios (up to 15:1) to minimize BSFC and maximize the sweet spot area on the map. Next generation MCE-5 VCRi engines will combine VCR and stoichiometric charges, highly diluted with external cooled EGR, in order to improve part loads efficiency by means of both the reduction in heat and pumping losses, and the optimization of compression-expansion ratio. This strategy, added to downsizing-donwspeeding, requires high-energy ignition systems to promote repeatable, stable, rapid and complete combustion. The combination of highly boosted micro-hybrid VCR, VVA, massive cooled external EGR and high-energy ignition systems promises an overall efficiency close to that of current full hybrid vehicles at much more affordable costs. After 12 years of intensive development, the MCE-5 VCRi technology has demonstrated its ability to serve such objectives under excellent functional and cost-effective conditions. Going forwards, the multifuel capabilities of the MCE-5 VCRi are considered, in view of their positive impacts on long-term energy sources diversification, energy independence, and CO2 emission reduction via renewable or low-carbon fuels.

Presenter
Vianney Rabhi, MCE-5 Development