Calculating base fuel pressure with AFP regulator?

Hi everyone, My name is Norm. I have an introduction forum started if anyone wants to know more mods about mt setup. So, I am trying to calculate my base fuel pressure on my 1991 Nissan 240sx with a KA24DE N/A equipped with a 255 walboro fuel pump, 550 cc/min injectors, and an ISR adjustable fuel pressure regulator. I have calculated that my injector PW at 6K RPMS should be 8.8ms. My question is, Is there a formula that i will need to avhieve my target injector PW?

Since you did your calculations at the rated 550cc/min flow, what is the specified fuel pressure for that rating. That is the fuel pressure you should use as a minimum.

It's likely to be 3 bar (43.5 psi), another common rating is 4 bar (58 psi). You can usually set a fuel pressure anywhere in that range, and tune the engine, just keep track of what fuel pressure is used for the tune/map/config.