new 7 hole Bosio nozzles for less smoke?

[Farfromovin]

Originally Posted by Rub87

I told this ages ago the the thermal load on pistons would be not equal so it would result in cracks around the bowl.. now someone should make a huge qoute of all the posts from Kerma where there say that the spray pattern is good as it is on the 7hole and that it's engineered by FB to work etc.. would be funny

I remember

Originally Posted by TornadoRed

IMO Bosio makes excellent nozzles, but it sounds like these 7-hole nozzles are an experiment that did not turn out successfully.

And IMO Bosio has had a horrid track record the last year. Nozzles not flowing as much as they should, spray angles wrong, hole patterns 180 out. Kinda glad I have OEM nozzles right now...

Originally Posted by Scott02

The bestest question is, why is the consumer paying for the experimentation???

Secondly, why is it that a person who sells them, seems to be the only person that says they are happy with them?

Exactly...

[Whitbread]

Well, I popped the nozzles last night and they all popped within 10 bar of each other. None dribbled or streamed (surprisingly). I even did the #3 probably 50 times haha. Still unfortunately doesn't tell 100% how the injector sprays at full injection pressure though .

I'm going to poll the #3 nozzle out and shoot some wd40 through it to try and see a little bit better of a pattern and any discrepancies.

[Scott02]

This seems to be a good time to post these thought provoking questions, although it's not the proper thread, but I still think it may be relevant to the people in this thread.

Questions.
When a nozzle pops inside the combustion chamber, what pressure is it spraying into?
(Hint: cylinder pressure at SOI)
When a nozzle pops on a tester, what pressure is it spraying into?
(Hint: atmospheric pressure ~ 1bar)

And the REAL question (and the reason I wanted to post this)

What effect does the GREATLY varying dP across the nozzle tip have on "SPRAY PATTERN" ???

[ccvdubs]

Less than 10K on this motor/components. R520 7 holes popped by reputable vendor and given clean bill of health. Car was not nearly as fast as it should be for what was done. Pulled to head for other reasons and found this;



# 1&2. Nice, light covering of soot as normal.


Upon closer inspection, noticed some scuffing on the cylinder wall directly in line with one of the injector holes.


Wiped my finger across the #3 piston and found a crack in the edge of the bowl lip right at the edge of the flame mark on the piston. Same flame mark that the wall scuffing is in line with.
[/quote]
What was motor torn down for? Was it overheated? Almost looks like you lost/ overheated a ring. Other mods? What intake manifold was used? Really curious about the scuffing on wall.

[Whitbread]

Originally Posted by ccvdubs

What was motor torn down for? Was it overheated? Almost looks like you lost/ overheated a ring. Other mods? What intake manifold was used? Really curious about the scuffing on wall.

Head was pulled for porting, valvesprings, and a cam. Motor was not overheated.

Car is running vnt20, 11mm, fmic, and stock intake w/racepipe.

I'm thinking the scuffing is a result of fuel washing seeing as it's directly in line with an injector hole and that particular hole looks to be spraying too much/wrong angle judging by mark on th piston.

[cog]

what i want to know is are the newer 764 7 hole any better , i know they maybe not as efficient as race 520s when fully maxed out with 11mm and 12mm pumps , but they should be allot better in terms of performance than pp764 for people like me who have a smaller turbo and 10mm pump , i just need top know if bosio made any revisions of the 7 hole with th 764 or did they just figure out that with smaller holes it caused less heat on the bowl , im really concerned that 10-20k down the line these will break my car as a direct result , im not even sure how much more performace they give over pp764 or race 520 on my setup

[Scott02]

Originally Posted by Scott02

This seems to be a good time to post these thought provoking questions, although it's not the proper thread, but I still think it may be relevant to the people in this thread.

Questions.
When a nozzle pops inside the combustion chamber, what pressure is it spraying into?
(Hint: cylinder pressure at SOI)
When a nozzle pops on a tester, what pressure is it spraying into?
(Hint: atmospheric pressure ~ 1bar)

And the REAL question (and the reason I wanted to post this)

What effect does the GREATLY varying dP across the nozzle tip have on "SPRAY PATTERN" ???

No one has any opinions on this?

[Fix_Until_Broke]

Scott02 - I see what you're saying but not sure that the dP across the nozzle tip varies that much and even if it does the area that it acts upon is very small relative to the area that the fuel acts upon.

SOI cylinder pressure will be ~500 PSI during startup/low load conditions (similar to a compression test). SOI cylinder pressure even at double the mass of air in the cylinder at full load might be 1000 psi. This would effectively lower the absolute pressure required to open the injector, but only by the very small area of the needle tip exposed to the cylinder pressure. I'm just winging this here, but the differential area between the annular part where the fuel acts upon and the nose area where the cylinder acts upon has to be 10:1 or more.

So even a net 500 psi increase in cylinder pressure will only lower the absolute break pressure of the injector by 50 psi at the most.

[cog]

yes i have an opinion , like you id love to know all the answers to those very poinient questions , but as long as ive been tracking the 7 hole threads and speaking with other tuners no-one knows or has even done any longeveity testing that i can see of these nozzles . but you would have thought bosio had desihned theses for a reason , its not just a case of driling two more holes as its fairly clear that the whole spray angle and pattern is different but no one seems to have any answers other than charlie and anuthee , just with a dialy driver and family car i cant afford to be pulling out damaged pistons

[dieseleux]

Spray change with pressure, more pressure in cylinder, density of air are higher, less velocity on spray.

good doc here:
http://www.td.mw.tum.de/tum-td/de/fo...yinger/288.pdf
http://www.akademik.unsri.ac.id/down...s53197-202.pdf
http://www.fluent.com/solutions/automotive/ex244.pdf
http://www1.eere.energy.gov/vehicles...deer_busch.pdf
http://www.advancedinjection.com/med...0_ismailov.pdf

and also seach for: slides_droplet.pdf


Dieseleux

[Scott02]

Originally Posted by dieseleux

Spray change with pressure, more pressure in cylinder, density of air are higher, less velocity on spray.

I agree completely.

Originally Posted by Fix_Until_Broke

Scott02 - I see what you're saying but not sure that the dP across the nozzle tip varies that much and even if it does the area that it acts upon is very small relative to the area that the fuel acts upon.

SOI cylinder pressure will be ~500 PSI during startup/low load conditions (similar to a compression test). SOI cylinder pressure even at double the mass of air in the cylinder at full load might be 1000 psi. This would effectively lower the absolute pressure required to open the injector, but only by the very small area of the needle tip exposed to the cylinder pressure. I'm just winging this here, but the differential area between the annular part where the fuel acts upon and the nose area where the cylinder acts upon has to be 10:1 or more.

So even a net 500 psi increase in cylinder pressure will only lower the absolute break pressure of the injector by 50 psi at the most.

From one of my pop pressure summary sheets I have:
Pilot/Primary = 240bar/300bar = 3481psig/4351psig = 3495.7psia/4365.7psia

The pilot pop dP when pop testing is 3495.7psia/14.7psia or 237:1
The pilot pop dP in the engine is 3481psig/~500psig or 6.7:1

Surely this has more of an effect that most think it does.


But when Whitbread pop tested these nozzles, I'm assuming that he was only looking at the spray pattern of the Primary injection.
Which my noggin tells me is even a worse situation than the Pilot injection stated above.

My reasoning is when that primary injection ignites, it's going to raise that normal cylinder pressure of 500psig up even higher. How much higher, i have no way of quantifying, but it will make the difference in dP's even worse than the above stated numbers.

...Or this is at least what my head has been telling me, and is something that has been bothering me for a very long time.
Someone smarter than me, please feel free to set me straight if i'm wrong on all this.

Comments?

EDIT: and of course this this is talking the cylinder pressures at idle, and no boost added.

[Whitbread]

Pulled the pistons out yesterday, so here's some better pics.











The heat marks in the #1&2 pistons are correct and in the bowl. However, on the #3, they're clearly out of the bowl.

[dieseleux]

All the key is understand how injector works, how fuel pressure open needle.
You have 3 pressure, injection line pressure, cylinder pressure, fuel return line pressure.
To open nozzle, you need more pressure on needle than spring push.
To move needle, fuel push not on full surface of needle when needle are close, this is make hysteresis on open/close pressure.
When needle are close, cylinder pressure push only on a small part of needle tip surface, cylinder pressure are low effect on injector.
I never test that... if you put 100psi on fuel return line (easy to do with air), i think is raise pop pressure by 100psi!


Dieseleux

[Fix_Until_Broke]

Originally Posted by Scott02

..........

The pilot pop dP when pop testing is 3495.7psia/14.7psia or 237:1
The pilot pop dP in the engine is 3481psig/~500psig or 6.7:1

Surely this has more of an effect that most think it does.

While your ratio's are mathmatically correct, it does not represent how the injector actually works like dieseleux explained

Just think of the injector pin only.

There are 3 areas for pressure to work on

Area 1: Full diameter that slides in the injector nozzle - 4-5mm diameter?
Area 2: Seat diameter - the little 1-2 mm diameter area where the pin seats on the nozzle when it's all the way down
Area 3: The annular ring shaped area on the "side" of the pin which is the difference between Area 1 and Area 2.

So return line back pressure acts on Area 1 - we'll assume it's zero for this discussion.
Fuel from the injection pump acts on Area 2
Combustion chamber pressure acts on Area 3

Fuel pressure on area 2 has to overcome the mechanical spring force pushing down on the pin to lift it. Area 2 divided by the "pop" pressure = the spring force.

Cylinder pressure acts on Area 3 and for lack of having any real measurements we'll assume that it's 1/10 the area of Area 2. Pressure on Area 3 adds to the force lifting the pin but only at 10% since it only has 10% of the area of Area 2. So a 500 psi increase in pressure on area 3 has a 50 psi (lower) effect on the pressure required at Area 2 to lift the pin.

Pressure at Area 1 (return) adds 10% to the pressure required at Area 2 since it's area is 110% of Area 2 (Area 2 (10) + Area 3 (1) = Area 1 (11)).

I'll try and draw a picture later and scan it in.

[Gearhead51]

Hrmm... Those Bosch .216 nozzles are looking pretty good to me right now. Not nearly as big, but they're a known quantity, correct?