Supersonic diesel fuel jets were generated by a compact gas gun. Using a metal piston as a momentum exchanger of impacting projectile, diesel fuel was injected into the atmosphere through a five-hole diesel injector. Diesel fuel was also injected through titanium alloy nozzles with single and double holes. Air shock wave structure and jet shapes were visualized by a double exposure holographic interferometry. In the two-hole nozzle experiment, two supersonic fuel jets with a 30° diverging angle were produced. The shock-shock interaction and shock-jet interaction were examined. In the cases of two parallel supersonic jets and two opposed supersonic jets, merger and liquid fragmentation appeared. In the injection, the jet-jet interaction created complicated multi-shock-waves around the fuel jet. A pressure chamber coupled with a PVDF (Polyvinylidendifluorid) pressure gauge was designed for measuring the pressure inside nozzles caused by the metal piston compression after the primary impact of a projectile. The high frequency response pressure gauge recorded the structure of the pressure wave with a peak pressure value of about 140 MPa.