Bleeds off takeoff

[kingfosco 0]

Maybe therefore duct pressure?

[kevinh 409]

Maybe therefore duct pressure?

No, it's not directly related. Anyway the calculations are made even if there is no duct pressure. The FMC computes the effect on the N1 limit for the selected thrust rating from ambient conditions (altitude, press, temperature, etc) and then that is factored according to how many pack switches are on, whether any are in high flow, how many bleeds are open and whether the isolation valve is open or closed.  The EEC makes the same calculations as a backup.