Swirl matching to injector tip design

Fahlin Racing

Fahlin Racing

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After researching and picking the brains of those most knowledgable in fuels, one guy had mentioned to me matching the swirl (turbulence if you like) to our injector nozzle orifice count should help produce a more complete burn.

Since we have only really struck bowl design and injection pressures for proper mixing, I wonder how much finer we can tune with this thought provoking our minds. This of course would also change fuel possibilities as well if we can achieve a certain point :pop:

shallow, deep, narrow or wide bowls I think this, understood, would explain why more than one size and shape of combustion chamber could produce positive effects.
 
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Although one might consider the spray of a high orifice count/low diameter orifice very emulsified and susceptible to intake turbulence, heavier fuel jets seem to propagate combustion aggressively and produce higher cylinder pressure. I don't have tangible data for this but I'll be doing a butt dyno test between ~152* 7 hole injectors and 145* 5 hole injectors.
 
Nice Straight6, I believe your bowl design is the constant then?

The end result of this subject alone will most likely be variable since there can be numerous setups that may work for power increases, however the application a certain design may be tested with can show if its fit to fight in that particular engine platform or not.

If the fuel is heavier, but we employ a higher orifice count, we can encounter a shorter penetration of the fuel but ifthe fuel may be heavier than normal would that make up for the reduced droplet size in turn have also a better point of distillation for our flame front (diffusion flame). Perhaps influencing our evaporation rate we should add viscosity as our orifice count rises?
 
Time would be better spend matching injector tip to bowl geometry than highly variable swirl ratio.

As you increase the cylinder pressure ratio spray penetration decreases through the high density air mass. However generally when we match fuel flow we increase nozzle hole diameter and this greater cross section of fuel spray will penetrate further into the air mass. Back into balance have you.

Higher spray pressure does not penetrate further it is actually the opposite .
 
my experience with 7x.010 148* nozzles versus 5x.012 155* nozzles was that the 7 hole made more power down low and did it cleaner considering the fueling. Up top, not so good. Could be due to the lower amount of force / mass per fuel jet. Weston clued me into that a few months back when trying different injectors.
Sure you can mod these ppumps for more fuel.. but can you mod the injection pressure any higher? And if you could, would it buy you anything with nozzles that had more holes?
swirl just helps with air / fuel mixing. too much and like you said maybe it hits the sides of the bowl and makes more soot with less power.
Diesel engine manufacturers sure seem to think swirl is important for economy at low load use, judging by the designs out there.
Youd need some pretty expensive equipment to verify a lot of this stuff. =(

I swear I did better (power / economy) with my lightly modded 160 pump than this 215 I got on there now. But so much has changed I cant say for certain =(
 
kawi600 said:
my experience with 7x.010 148* nozzles versus 5x.012 155* nozzles was that the 7 hole made more power down low and did it cleaner considering the fueling. Up top, not so good. Could be due to the lower amount of force / mass per fuel jet. Weston clued me into that a few months back when trying different injectors.
Sure you can mod these ppumps for more fuel.. but can you mod the injection pressure any higher? And if you could, would it buy you anything with nozzles that had more holes?
swirl just helps with air / fuel mixing. too much and like you said maybe it hits the sides of the bowl and makes more soot with less power.
Diesel engine manufacturers sure seem to think swirl is important for economy at low load use, judging by the designs out there.
Youd need some pretty expensive equipment to verify a lot of this stuff. =(

I swear I did better (power / economy) with my lightly modded 160 pump than this 215 I got on there now. But so much has changed I cant say for certain =(
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So did you make more power with fewer holes? I have a set of 6 x .019's that flow slightly more than my 7 x .013's and have wondered how they would compare on top.
 
I made more power at lower RPM. Could be a coincidence, or the effect of lower penetration at higher boost levels.
 
The 7-hole nozzle is from a John Deere application, yet after extensive dyno testing almost all John Deere competition engines use a 5-hole Mack nozzle.
 
Smokem said:
The 7-hole nozzle is from a John Deere application, yet after extensive dyno testing almost all John Deere competition engines use a 5-hole Mack nozzle.
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You mean the ones that aren't running the 4 hole.
 
4-hole nozzles are very common, especially in older injection systems or agricultural applications.
 
However generally when we match fuel flow we increase nozzle hole diameter and this greater cross section of fuel spray will penetrate further into the air mass.
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I wouldn't doubt our droplet size will have an effect on penetration. Tuning the last bit of the engine's HP making capability the tiny pieces are looked at. Sure we can load up the chamber with fuel and combustible air, we make power, but thoroughly burning more will be more difficult. Even being minute.

Most engines, if you are looking down into the cylinder, Duramax head, Cummins, Ford have a position to produce a clockwise swirl action. Chevy employed some tapered half-moon areas on the intakes, Cummins used the swirl ramps. Since hot gases move more quickly, I would see piston speed in relation to crown design also influence our actual in-cylinder turbulence and mixing rate. If we put the head on a slow bench and hook a swirl meter to it, we only see what the cylinder sees when the piston is at or around BDC. It doesn't show what may go on or happen when our piston is causing on the compression stroke.

If our injection penetrates less and less as cylinder pressures rise, would these multi point be doing what a rise in fuel injection pressure does? I think so, but again we must match without causing centrifuge of the injected fuel. I think if we want to employ higher static ratios, we must tear up the droplets more aggressively and allow the fuel itself to be able to evaporate and become stoichmetric in as large of an area as possible so we can burn sooner and quicker. As of yet, I haven't seen a 'strength of swirl' reference mentioned.

This topic can be wide, racing mills to an irrigation pump, efficiency is needed in more than just in our trucks.

Here are some factors I believe contribute to swirl or lessen it
Port layout (runner angle)
Port dimensions (CSA, Convergent area of port, Divergent are of port)
Valve design
Bowl design
Fuel injector design (interia of fuel)
Quench region
Piston speed
Boost pressure
Static comp. ratio
Dynamic comp.
 
Joe, have you seen any injector try incorporating a spray that can spray outward but also directing the fuel droplets in a circular action similar in swirl?
 
Here is a thought,

Dealing with minimal penetration due to...

High cylinder pressure and high injector tip orifice count

I believe the in-cylinder turbulence should be more intense if we must mix a more dense collected mixture within the cylinder.

Dealing with adequate injection penetration....

High cylinder pressure and a lower injection tip orifice count

I believe that our turbulence should be less agressive because the amount of fuel propagation in the chamber is exposed to more area of the chamber, and in turn, spread around with more swirl activity due to the larger area that the fuel has come into.

If we are raising our rpms, could we rely on the compression mostly similar to how the prostockers do in their engines in drag racing by not entirely relying on full-tilt mixture motion?
 
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