There are some who comment that if they told me the sky was blue, I'd have to go outside and check.
The comment, coming second hand from someone who doesn't always get their facts straight, is just another opinion, and not necessarily correct. For example, we recently read from a performance thread that,"..extrude honing destroys injector nozzles...", which we have seen people take the honing to an extreme and wreck them, but there is this information from a Bosch website...
When Bosch says they use 'hydraulic grinding', it's because they can't say Extrude Honing, as that is a registered copywrite name. Not only does honing improve flow, there are two methods; a clay compound pressed through the passages and an oil slurry, that can be pushed and pulled through the orifices. These methods reduce cavitation and increase flow by smoothing out the injector fuel bore. A Michigan company we know uses both methods to make some of the best Cummins race nozzles around.
When we say they must pop and stop, and I don't know who has actually seen the spray pattern operated with high-speed photography, under actual operating conditions. But I know that common rail injections are separate injections, as seen on our oscilloscope.
No matter, if we are testing nozzles and the nozzle's pop pressure are individually tested for NOP1 and NOP2. If the nozzle does not control fueling without leaking or spraying, that nozzle may perform well in emulation on some test equipment, but fail in actual operation. Much changes compared to spray patterning into ambient air pressure or the extreme pressure of a charged cylinder.
We usually see only the worst of the nozzles which have melted or cracked pistons, when we get an engine to overhaul that has blown up. When we check them, the offending cylinders always have an injector that are near runaway fueling. I can fix some of these injectors, but most of the time, even injectors with less than 1,000 miles, these are injectors that never should have been installed, as they are faulty.
I don't expect anyone to follow our protocol, but we now install injectors in a vehicle with an engine in excellent condition, a great injection pump and 500 psi compression across the board. We check idle balance, fuel economy and drive them for effect. This has all but eliminated claims that 'these injectors don't work right.'
Nevada_TDI,
As I just said, getting idle balance and FE readings are the proof the injectors are working correctly. However, this is based on injectors that are popping at pressures at least, close to normal 220/ 300 bar. If the pressures are low, the idle balance will be close, regardless of disparity of fueling. There is a bell curve of fueling that you can plot by running NOP2 through a range of pressures, usually becoming more stable above 280 bar and losing consistency above 330 bar. Our opinion for setting injectors 'hot' at pressures above optimal settings will strain the injection pump and the injector will become more erratic. One of the benefits of hydraulic honing is to reduce cavitation as fuel enters the injector hole, but extreme pressures will negate the honing benefit.
We do not subscribe to the 'one size fits all', from 100-200hp nozzles.
I might add, the 1019/955 nozzles that we popularized have little, if anything, to do with the sizing of the a nozzle sold by the same number. You can just about say that about any of the nozzles copied by others who use Bosch numbers to hawk them. Call them clones, copies or even fakes, they rarely act the same as the original.