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+--- Thread: nozzles for increased flow (/showthread.php?tid=832)
nozzles for increased flow - tomnik - 11-11-2009
Hi,
for the first time I got flow data for the 261 nozzles and for a custom made set of 6.
261: approx. 3.4 l/min @ 100bar
custom made: 4.5 l/min @ 100bar
My buddy brought a handfull of 248 original BOSCH, brand new and asked me to get them modified.
I ended up using a new needle (of the 261) and lap it into the nozzle body. To get the increased flow I increased the needle lift.
Comparing the custom made and the 261, besides flow the pre spray effect should be more on the custom made, the body bore is slightly smaller on the 248.
My expectation is smoother run in combination with capability for increased flow and/or reduced spray duration (the same quantity within a shorter time corresponding to IPs with larger elements).
Today I will send the nozzles to my buddy (who is extremely sensitive to engine noise). He will adjust them to 140 bar and test them in his 603a.
Results maybe next week.
The background is that he has 250 pieces more of the brand new 248.
Depending on the results this limited edition will be produced.
Regarding the cost I have to calculate. This first set was free of charge for testing, before the production run of the 250 pieces I have to discuss with the manufacturing company.
Tom (again like a kid on X-mas)
RE: nozzles for increased flow - ForcedInduction - 11-11-2009
The stock nozzles aren't a restriction, I don't see much benefit in enlarging them for minimal gains.
RE: nozzles for increased flow - tomnik - 11-11-2009
Maybe no restriction, o.k.
But I had the chance and possibility to modify more or less worthless nozzles.
Intrersting for me is the combination with larger elements where a high flow within a short time has to pass the nozzle. I will compare these with the stock nozzles on my MW65 Holly IP.
Further it is interesting to see how the different pre spray changes the run and performance of the engine.
You know best what influence nozzles have on torque and sound.
Tom
RE: nozzles for increased flow - E300TSC - 11-11-2009
Tom, I still have the new nozzles I got from you. The extra shims are arriving some time this week (after close to a year wait!) and I will be able to install them.
RE: nozzles for increased flow - tomnik - 11-11-2009
(11-11-2009, 05:24 AM)E300TSC Tom, I still have the new nozzles I got from you. The extra shims are arriving some time this week (after close to a year wait!) and I will be able to install them.
When Peter is here for X-mas I'll give him a set of the newest custom nozzles for you to compare them with the current ones you have.
(hope to have an additional set ready at that time).
Tom
RE: nozzles for increased flow - Tymbrymi - 11-11-2009
(11-11-2009, 04:10 AM)tomnik ...in combination with capability for increased flow and/or reduced spray duration (the same quantity within a shorter time corresponding to IPs with larger elements)
That is where the benefit to the nozzles is all about!! I hadn't thought about that before. I would say we've seen proof from the Finns that the stock nozzles can flow all the fuel we need, but if the needle lift duration exceeds the amount duration of IP plunger lift, this will decrease the amount of time to inject the fuel to the duration of IP plunger lift (or at least head in that direction). I'm looking forward to the results!
Thanks for that perspective too. 
One potential problem with the extra needle lift is the return pressure wave when the needle closes. As I'm sure you know, at the time scale and pressures involved the fuel is actually compressible, which causes a reflected pressure wave to the IP. The delivery valve is supposed to "absorb" that reflection to prevent it from reflecting back to the injector and causing a second injection event. With the increased needle lift the delivery valve may not be able to fully dampen the initial return pressure wave... One way to find out!
RE: nozzles for increased flow - ForcedInduction - 11-11-2009
The injection system is no different than any other hydraulic system, a plunger is pushing an incompressible fluid to a working surface (nozzles).
Changing nozzles doesn't increase the volume of flow at all, that is set by the plungers, it reduces the working line pressure (keeps it closer to the pop pressure) and lets the nozzle do its chattering for optimal atomization. Nozzles that flow poorly for the volume of fuel injected stay off the seat longer and produce a stream of fuel instead of mist.
Also, with short needle travel a less intense pressure wave is produced.
RE: nozzles for increased flow - Tymbrymi - 11-11-2009
(11-11-2009, 02:08 PM)ForcedInduction The injection system is no different than any other hydraulic system, a plunger is pushing an incompressible fluid to a working surface (nozzles).
No. At the time frames we are working with, the fluid is *definitely* compressible. I have read this in multiple sources of literature (peer reviewed scientific journals, Bosch, etc).
Besides, if it is incompressible, how else can you have a pressure wave?
RE: nozzles for increased flow - ForcedInduction - 11-11-2009
(11-11-2009, 02:33 PM)Tymbrymi Besides, if it is incompressible, how else can you have a pressure wave?
Its not the fluid compressing, its the metal around it expanding. The pressure wave is just fluid hammer.
Bulk modulus.
X (% compressed) * 1.3 GPa (diesel) = 0.013 GPa (injection pressure).
X=0.01, or, diesel's volume is reduced by 0.01% at 135bar.
RE: nozzles for increased flow - tomnik - 11-11-2009
...
anyway I am prepared for delivery mods.
Tom