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Hope you won't mind if I use it at some point on my 'fuelling' page, it tallies with the style of the site.
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Sure feel free, I like analogies to discribe complex issues, and tend to collect them. I probably adapted someone elses analogy I saw some place else.
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Is it possible to mix Air + Fuel better, or is there just not enough time?
There are some "snake-oil" products available, like a "cyclone" that creates a whirl-wind after the airfilter N/A engine or before the trottle body.
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Yes it is desirable to improve mixing, that is one of the ways they get ultra lean mixtures to burn. They intentionally create a turbulence pattern in the cylinder that creates a slighly richer mixture near the sparkplug to get reliable early ignition then the flame front progresses into a mixture that would normally be too lean to ignite easily.
High turbulence in the combustion chamber also helps create a quick burn and reduces the tendency to detonate.
Unfortunately creating turbulence / swirl in front of the carburator / throttle body does not translate to increased swirl/turbulence in the combustion chamber. The intake manifold and valves completely dominate the process of creating organized motion in the combustion chamber during the intake stroke. The shape of the combustion chamber,cylinder head and piston crown completely dominate turbulence/swirl or tumble created in the combustion gases during the power stroke.
The air swirl type products are an interesting example of something that actually works slightly in a very small set of circumstances. But only on certain carburated cars. The improvement is so small as to be difficult to measure. A professional race engine builder tested one, and found some interesting things.
On a dyno he could see very small hp gains at certain rpm points, but got no increase in gas milage in road tests. The device created tremendous swirl when tested by itself on a flow bench, but the intake swirl was completely killed by the carburator and was not measurable beyond the carburator throttle plates, when the entire intake tract was measured. The fact that it made small gains is probably more a testament to the fact the carburator was not working at its best, than a testament to any revolutionary developement in engineering. The tremendous swirl apparently helped the carburator give slightly better fuel atomization at key rpm's and the small improvement the driver detects is more a case of drivability rather than performance, ie eliminating slight stumbles or flat spots.
You can actually make a car feel faster to a driver while making it run slower, by changing the way the power comes in. A car with very smooth uniform power increase does not feel as fast as a car that has moderate power up to midrange rpms then suddenly improves to a higher power level. The driver will interpret the sudden surge of acceleration to more power when in fact it may only be a case of lower power production at low rpm.
Larry