I am trying to calculate the nozzle sac pressure required to deliver 60mm3/ms of diesel fuel into a pressurised cylinder (19MPa). The nozzle has 5 delivery holes of diameter 0.157mm and the discharge co-efficient is 0.87. The sac diameter= 0.7 mm and the sac volume= 0.12mm3. I have tried to use the equation below: Q=Cd x sqrt(2deltaP/rho) x A2/sqrt(1-(A2/A1)^2) , solving for delta P where p2 = 19MPa. p1= unknown (wanted item) A2 = Sum of the 5 hole areas A1=Sac area rho= density of diesel However I am getting incorrect answers, is there something I am missing or doing incorrecty? Please let me know!