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Emulsion "travel"
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Author:  treyrags [ Mon Jan 14, 2013 2:04 pm ]
Post subject:  Emulsion "travel"

Assuming a load condition where multiple emulsion bleeds are below the top of the main well level in a modular carb: Would the bubbles drawn through the smaller bleeds travel toward the booster faster than the larger ones? If so, I would think the lower bleeds need to be equal or slightly larger so those bubbles don't "catch" the higher ones and coalesce? Bruce, Mark?

Author:  treyrags [ Tue Jan 15, 2013 2:57 pm ]
Post subject:  Re: Emulsion "travel"

I found this post by Bruce that clears up a lot.

shrinker wrote:
Superior in what way? Consider that air bubbles lower the density, So therefore that lower density fuel 'floats' on top of the normal fuel. that causes the lower density fuel to have a higher surface level than normal density fuel. Once the surface level is up to the height of the outlet tube it can flow to the booster. Thats when the engine starts to run on that fuel. At low air flow levels thats all that happens. Your using air to make the surface of the fuel closer to the outlet. At higher flows through the carby the main jet restriction causes sufficient reduction of the liquid level in the well to fully uncover some bleeds. When its like that the air flow through the bleeds blows the fuel along its path. The amount of blow etc is controlled by the MAB and the sizing of the various E-bleeds. Now also think about what happens when the fuel flow into the bowl causes a lowering of the level. That means the pressure on the entrance to the main jet is changed, so the flow rate of the jet alters and that alters the level of fuel in the well. Now what happens if you change the main jet size? Same thing isnt it.

Ok so now put all the emulsion holes on a tube like the Weber plates. If you make them in the same arrangement as a Holley then it will do very similar things. But because you have a tube you have lots of places to put the E-bleeds, you can place them all at one level if you wish and that allows you to have lots of fine bubbles at one place, you can have lots of air but have it as fine bubbles. If you try to do that with the Holley design you can only have one hole and it has to be big to pass the air and then you only get one bubble of air. You get a different density change if the bubbles are one single one or lots of tiny ones. Lots of tiny ones creates lower density. Big bubbles travel faster though. do a experiment with an aerator on a faucet outlet at the kitchen sink. When your filling a glass with non aerated water the big bubbles float up quickly. When you fill it with an aerator nozzle the tiny small bubbles take longer to float up. BUT small bubbles just alter the density and viscocity, where as big bubbles can form a block of air moving through a tube. So when you have a block of air exiting the booster where is the fuel for that parcel of metered air? What does that cylinder run on then?
So now what do you do with the carby, will a large bottom air bleed get you a big enough droplet to blow fuel faster to the booster at high CFM flows? Will tiny bubbles help it start the mains flow differently at low CFM flows?
So answer this question, Which bubble structure will create more even fuel distribution exiting from the carby base?

Ok so know work out how you would make a droplet flow in a stream of air inside the drillings of the carby. How much air do you need to keep a droplet and not have the fuel as a liquid with air bubbles in it. Think about how to make it air with droplets in it, thats the other way around isnt it. pretty obvious you needs lots and lots of air.
Ok so now how do you get that main jet to start making droplets instead of just passing liquid, how do you get the outlet of the main jet to form a droplet and then keep it as it smashes into the right angle bend trying to turn into the well? (Then go read what Jmarkaudio pointed out that I said on ST)

Now think about how a straight tube like used in the C&S alcohol varieties instead of a booster might discharge, what is going to be coming out of the tube?
Now what happens when you drill out the discharge tube on a booster, does it slow the flow or does it create a greater surface area around the tube internal circumference for the fuel to wick along and allow air to go down the middle?

Very interactive isnt it.

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