Evaluation of Emissions from an Engine with Phase Shifted Intake Valves

The intake valves of a 1.0 liter, 16-valve production engine has been phase shifted to increase the intake air charge, aiming at improved performance. The engine has been tested in a dynamometer bench to verify the performance attained with the modification and its influence on raw exhaust emissions. Total hydrocarbons, carbon monoxide, nitric oxide and oxides of nitrogen emissions were analyzed for varying load and engine speed. The results have shown that shifting the valves of a dual intake valves engine can provide increased performance, while keeping emissions at acceptable levels.