Sliced a model with exact same settings, other than nozzle and layer height, to compare. Using Bambu brand PLA and a simple but somewhat large part.
0.4 nozzle - 0.2 mm layer height - 4h 24m
0.6 nozzle - 0.36 mm layer height - 4h 50m
Using stock Bambu Labs flow settings. What am I missing?
Nothing. Without modification, the BBL printer is already operating at its maximum flow rate. So you will just have slower movement for the 0.6mm nozzle, while the 0,4mm one will move faster.
So the time will be always be similar.
But higher layer heights can cause bridging, more overhangs, etc. where the slicer will slow it down. I have had it a few times, that it was slower with the 0.6mm nozzle.
Thanks for the reply. I was thinking that may be the case, but then I don’t see the point of printing with anything larger than 0.4mm nozzles. Guess I’ll switch back to the 0.4mm.
larger size nozzles allow for stronger structures generally is an advantage but less detail and can be slower outside of vasemode
The .6 nozzle is no allrounder as the .4 nozzle is. The .6 nozzle is better for abrasive materials and material containing carbon fibre, like Bambu Lab PLA-CF.
I‘m using it for technical models which need to be stronger, take a long time to print and/or no high details are needed. Lastly I printed wheels for a mower. With the .4 nozzle the print took about 11 hours. With the .6 nozzle the print took only 6 hours. But therefore I used 0.3 layer height, reduced the infill and the walls because the line width of the .6 nozzle is 50 percent wider as the lines of the .4 nozzle.
Anyway changing the nozzle size requires adapting the printing settings to have advantages. 
With the same settings on a multi colour print you will see that the 0.6s larger layer heights reduce print times quite a lot.
When you change the nozzle size profile, even though the filament profile name does not change, the settings do. BBL is sneaky with settings.
Use the compare tool and just change the printer nozzle profile and you will see all the settings that change. You will also see the actual settings file names are different.
@julie777 Wow! I have learned something new today. Didn’t realize until now there was a compare tool. Makes things a lot easier, thanks for mention that.
I got the E3D 0.6 nozzle for the sole reason I wanted the better strengths (like @print.in.3d ). Also, the E3D should support higher flow rates, but that is not why I installed it. Given that this is a Bambu / E3D collaboration I feel like they should eventually provide special profiles adapted to the higher flow rate nozzle. Not that in my use case it matters much.