An attempt has been made to study the combustion and emission characteristics of ultra-low diesel fuel for high speed direct injection ( HSDI) diesel engine at different fuel injection timings( -12,-9,-6,-3,0 )ATDC . The fuel injection pressure was 800 bar and at high load ( 80Nm= 5BMAP) , low load ( 40Nm=2.5BMAP ) , With constant engine speed ( 1500rpm) . In-cylinder pressure was measured and then analyzes this pressure using LABVIWE program and calculation program in MATLAB software to extract the apparent heat release rate, the ignition delay, combustion duration and the amount of heat released during the premixed and diffusion combustion phases . The influence of injection timing on the exhaust emissions such as carbon monoxide (CO), total hydrocarbons (THCs), nitric oxides (NOx), smoke number (SN) and fuel consumption were also investigated.
A result referring to that the retardation of the injection timing lead to increase the ignition delay and therefore the premixed burn fraction which plays a key role in the combustion and emission characteristics .this leads to change combustion mode to low temperature combustion at late injection timing.