For the OP:
All nozzles will atomize better (make smaller droplets) at higher pressure. This is in direct correlation with mass-flow of course. The upper pressure limit for a given injector is AFAIK
usually not determined by the ability to atomize, but by the ability of components to handle higher pressure. For example at too high pressure a valve may not be able to open at all- that would set a natural maximum for the pressure rating. There are also other effects like chatter etc. that might limit the pressure range.
So should we always crank the pressure to maximum allowed by the injector?
- At higher pressures, especially for large injectors, the opening times under low load get VERY small and hard to control
- operating anything at it's limit will increase it's probability to fail
- Atomization is only very important at low loads and idle. High load and boost don't really need good atomization.
- You quickly get to the point of diminishing returns. See graph below on droplet size
This is a graph of droplet size on agricultural spray nozzles at different pressures (and the resulting different flow rates). You can see that the change from 1bar to 2bar is significant, but the change from 2bar to 3bar is rather small. Nozzles will reach a point where atomization does not improve much with higher pressure, yet flow rates will still increase.
All that being said, Bosch does extensive research on their nozzles. So when they claim an operating pressure range for their injectors, we can be reasonably certain, that they will work very well anywhere in that range.
My suggestion: run at the lowest pressure that allows you a duty-cycle of 80% or below, as long as you meet minimum pressure requirements (not sure what those are on EV14s).
I understand that agricultural nozzles are not the same as fuel injectors. Those droplet sizes would be horrible for internal combustion engines. But they do work very well for pesticides. There are similar graphs for fuel injectors, but they are covered by confidentiality agreements.
If somebody wants to send me a pump, some hoses, a pressure regulator and a few injectors, I can take some laser diffraction measurements of the resulting droplet sizes. I will use water though- spraying fuel all over our warehouse or lab is not a great idea...