Experimental and Simulation Analysis of PFI-SI Engine for Fuel Economy Improvement

Variable Valve Timing (VVT) strategy on both intake and exhaust valves has a pivotal influence on the specific fuel consumptions and engine performance. In addition to this, fuel economy can also be enhanced by the application of Variable Compression Ratio (VCR) strategy.

This paper presents three possible strategies to enhance fuel economy improvement:

• A possible VVT strategy Early Intake Valve Opening (EIVO) and Late Exhaust Valve Closure (LEVC) that alters the valve overlap to reduce fuel consumption
• A two-position VCR system that improves fuel conversion factor to realize fuel economy
• A strategy that combines above two technologies to produce a complementary effect on fuel economy

All three strategies have been tested on a 1.8L DOHC four cylinder PFI engine. AVL BOOST a 1D engine gas exchange and cycle simulation code was used to model this engine to get fuel economy gains at part-load points. Therefore, the simulation provided essential information to understand engine thermodynamic process and VVT system development.