An experimental study on jet controlled compression ignition(JCCI) engine was conducted at all conditions on a prototype engine that was modified from a single cylinder diesel engine. The engine compression ratio was reduced to 12 to avoid auto-ignition of premixed diesel

and a small ignition chamber comprising a gas fuel injector and a spark plug was mounted on the cylinder head. Experiments were conducted at all loads to study the influences of ignition timing and load on the combustion controllability of a JCCI engine. The experimental results show that the combustion initial pointθ10 and middle point θ50 (referring to crank angles that correspond to 10% and 50% of total heat release) of premixed diesel change in one direction at most conditions. Its ignition delay is insensitive to load variation

indicating that a direct control of ignition timing for premixed combustion can be expected. However

the ignition delay starts to be reduced quickly at a point near full load due to an unexpected auto-ignition of premixed diesel. Therefore the effect of jet on the controllability of the ignition timing is weakened. The NOx and smoke are maintained at a low level at most conditions and they can be reduced greatly by advancing the spark timing due to their sensitivity to it. However

HC and CO are higher.