Diesel engines are the primary source of power for heavy duty vehicles; diesel engines have better fuel economy than equivalent gasoline engines and produce less green house gas emission. On the other hand, formation of smoke due to diffusion combustion and emission of oxides of nitrogen released due to high combustion temperatures are the major limitations of the existing diesel engine designs. Diesel engine manufacturers have to address these most critical situations to meet the future emissions regulations whilst improving performance and fuel economy at a minimal cost. The fuel economy, increased dynamic response and strict exhaust emission regulations resulted in invention of new technology development required improving the diesel engine performance along with exhaust emissions reduction. These improvements are made possible with new fueling technologies by improvements in combustion process through increased injection pressure. High pressure fuel injection results in better fuel atomisation and improves the fuel/air mixing to promote complete combustion, thereby increasing the fuel efficiency with emission control. The objective of this paper is to investigate the effect of fuel injection pressure on performance, fuel consumption and emission of a diesel engine. A study was done on a single cylinder 4 stroke direct injection diesel engine and the performance and emission characteristics were presented graphically. Based on experimental results, the best performance was found at 220 bar fuel injection pressure.

Key words: Diesel engine, Combustion process, Fuel injection pressure, Particulate matter, Nitrogen Oxide (NOx)