Low NoDx Emission With Better Fuel Economy By Nissan Naps-Z Fast Burn Engine

Careful study has been made of the aspects of unstable combustion due to heavy E.G.R. (Exhaust Gas Recirculation) while attempting to achieve low NO_x emission levels. The authors have concluded that the fast burn engine allowed a wider E.G.R. tolerance, with stable combustion, at very low NO_x emission levels in comparison with the conventional SI engine. This was true even under heavy E.G.R. Better fuel economy was achieved through a combination of improved cycle efficiency (using the fast burn concept) and reduced pumping loss (applying heavy E.G.R.). The Nissan NAPS-Z Fast Burn Engine was developed as a consequence of and through the use of the results mentioned above. The characteristic data of the engine (4 cyl. 1.8 ltr.) described in the paper showed a method of achieving a low NO_x emission level with better fuel economy and driveability.