Annular boosters on a Tunnel Ram
So, this is my interpretation from my post 58. A larger air bleed will start the system sooner as more air will increase the pressure difference and start the fuel to flow. This will also lean out the WOT. If the air bleed was increased too far, it eventually will flow no fuel. I also believe each set up will need its own mix, so each application will need its own experimentation to find the correct set up. O² sensors can misrepresent as to what the burn is actually doing. A lean reading can be a result of fuel and O² not mixing due to timing, flame propagation misfire, etc. Testing will need to be done. It was told to me by an engineer at work...think of fuel and O² molecules at a dance. The idea is to have gas and O² to be able to find their dance partner. Sometimes there isn't time to match up. It is far better to have too much gas and ensure all O² has a partner (rich) vs not enough (lean).
The fuel flow through the main jet is the result of the pressure difference between the atmospheric pressure in the float bowl and the venturi air velocity induced vacuum acting on the nozzle and the main well. The venturi vacuum in the well is reduced (the pressure is raised) by the "air leak" from the air bleed. This reduces the pressure difference that causes the flow through the main jet. If the air bleed were big enough, the pressure in the well would be the same as in the float bowl and no fuel would flow. Think about drinking through a soda straw with a hole in it above liquid level. Bigger hole, less soda. Suck harder, not much more soda. Big enough hole, no soda. This is the means by which the emulsion system can "lean it out on the top end". Incidentally, the vacuum that lifts water up a soda straw is in the most sensitive operating range for emulsion systems.
I wouldn’t call that your “interpretation” because you nailed it.
Thats exactly what it says, and that’s exactly how it works.
Its almost absurd watching a simple definition of how the MAB functions get so twisted up that it becomes convoluted.
The main air bleed can (and does) behave exactly as described above because (once again, exactly what it says in the text) the pressure differential across the booster and the MAB are different at different air flows.
Thats why a bigger MAB will START the mains SOONER and still make the fuel curve tilt leaner at higher air flows.
Evidently some can’t grasp the pressure differential at different air flows.
Regardless of all that, it’s really simple to test MAB function. All one needs to do is test it and you’ll find that Tuner’s explanation is exactly how it works.
Of course, I have the luxury of getting the phone and talking to Tuner to make sure I’m understanding what he wrote.
And your explanation is exactly what Tuner says and is exactly what happens in the real world.
I hope this ENDS all this BULLSHIT about MAB functions as it’s exhausting to keep unscrewing the bad information about it.
I have personally posted the GENERAL definition of it by Taylor. Of course, if you want the full explanation you need to get the books and read all of it. And grab a scientific notation calculation and work through the math of it. That makes crystal clear what is happening when you change the MAB.
This is PRECISELY how “holleyitis” happens. Bad information repeated over and over and over bolstered by misquotes, nonsense and repeated error.
This stuff is easily understood if you read what guys like Tuner and Shrinker have written. They have made it very simple.
You just have to shut out the noise and ignore those who say something diametrically opposed to what they are saying.