jlacoy82

Like the topic says, I work in fuel oil/heating systems, and today while playing around with a y8 intake mani and looking at the injector tips, I realized its not vastly different from an oil nozzle. I have no purpose for this info, I was just curious what (if any) angle fuel injectors sprayed at?

And I dont mean the angle at which they are oriented with the head, I mean the actual spray angle coming from the injector.

Like this---- ===<

With the < being the spray angle. 50 degrees? 90 degrees? Granted they probably arent all the same, just curious.

drdisco69

From the pictures I've seen, around 40 to 55 degrees. Like to know more as well.

jlacoy82

Really? That narrow? Seems odd, especially with the orientation they have in the intake runner.

drdisco69

I'm just thinking of all the various pictures I've seen of injector patterns, like these:




Heck, after looking at those, I'll say it's less than 45*

jlacoy82

Probably closer to 30*. Seems like it would be spraying more fuel onto the bottom of the intake runners than into the air. It only seems odd to me because in furnaces/boilers, the spray angle is determined by the shape of the blast chamber. If you have a long narrow chamber, you go with a low angle nozzle, as the flame is narrower and longer, and with wider, shorter chambers, you go with 80/90* nozzles to shorten the flame and widen it out.

There are problems when you put the wrong nozzle into the wrong chamber, and you get "impinging" where you are basically just spraying fuel onto the chamber wall and makes the burn very inefficient.

Does any of this pertain to intake runners/injectors, or is the air flow through the runners at such a velocity that the fuel spray is actually pulled sideways into the head before it has a chance to just spray all over the bottom of the intake runner?

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlacoy82 &raquo;</TD></TR><TR><TD CLASS="quote">the air flow through the runners at such a velocity that the fuel spray is actually pulled sideways into the head before it has a chance to just spray all over the bottom of the intake runner?</TD></TR></TABLE>

I think thats the key right there. Besides, look at the angle of the injectors in the manifold, and where they are pointed: directly at the intake valves. The shallow angle down the bend of the head, the angle of the injectors and the velocity of the air mean that the fuel goes straight into the head and combustion chamber, almost no turning required. This ensures that very little fuel will collect on the sides of the intake maifold.

Lets here some other opinions! Isn't any one else out there?

jlacoy82

Yeah, after I posted I realized I forgot to consider the angle of the injectors in relation to the head/runners. I suppose at worst there is some spray hitting the floor of the intake ports and maybe at the splitter. I'm only familiar with the insides of a d16 head, so if none of this applies to a b-series, I'm just speaking from what I've seen before.

drdisco69

And I am looking at the B16 head on my floor, so we have a good comparison.

jlacoy82

Regardless, I'm sure the injector spray pattern is probably pretty much optimized through years of experimenting/trail and error. Its give and take I suppose. The wider you make the angle, the more spray you'll have hitting the walls, and I dont know how much clearance it has in the first place to the little "dip" I guess I would call it at the top of the intake port on the head where the injector tip is close to. While if you made it narrower, you are just spraying more at divider, and under non-vtec conditions, you'd just be spraying fuel into an unused port bowl where it would sit collecting until vtec was called on for and that set of valves opened?

I dunno, if there was a way to experiment I would love to, or to find some online literature about it. Would be pretty cool to be able to optimize your injectors/fuel delivery through some port work and injector spray pattern adjusting.

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlacoy82 &raquo;</TD></TR><TR><TD CLASS="quote">you'd just be spraying fuel into an unused port bowl where it would sit collecting until vtec was called on for and that set of valves opened?</TD></TR></TABLE>

Once again, Honda is a step ahead. The base lobes of the cam don't leave one valve closed, instead, it opens it very slightly for this very reason, to prevent fuel from pooling on top of the valve. What, you think they're some kind of amateurs over there or something?

jlacoy82

Nope, I just didnt know that! Imagine that, I learned something! I mean, if they already figured out how to dump the excess fuel, then they must know SOMETHING about how the fuel injectors work and have their working setup pretty optimized already.

drdisco69

Yeah, I hear they make pretty decent motors too.

I was wondering the same thing, if after some headwork and other mods, you could find a couple hp from moving injectors. Definitely not cost effective, but interesting. I'm sure the BAR Honda team knows the answer, as well as any other engine design team.

Bump for things I don't know that someone else surely does.

sivathan

Saw this while browsing the web. Spray angles used in automotive injectors vary quite a bit. For example some of the multiple plume ones, the individual plumes can be as low as 10. See pictures of the multiple plume ones.
For dual plumes, typically each plume is about 12 degrees and together
with separation could be up to 30 degrees. See picture of dual plume one . However,
these are just some random examples and the variety is quite astonishing.