Ok. So from EDA we have 2*GW +80 et from Compressor stall 2*GW +85.
I am not mentioning the 1kt per thousand feet above 20,000. This rule is valid in any variant.
Could there be more to it than the engines?
Is there another reason why some aircraft variants have different GD calculations? Of course I understand this in case of a 319, 318, 321, each has various weight limitations and power available.
But considering the same aircraft type (A320), is there a place I can find info about the reason for the GD calculation differences?
In the new FCOM it is written that holding speed for CFM is GD and for IAE is GD+20. Reading this kinda reinforced my belief that GD calculation difference was directly (and only?) based on engine variants.
Now I am not so sure...
Any further source welcome!