This is a relevant test I performed back in 2005.
Quote:
I had a chance to thoroughly test the "Tornado fuel saver" device on a 2005 Elantra, which is a multiport fuel injected 2.0 liter engine with automatic transmission and cruise control. The car tests very consistantly and gets fairly high mileage already which helps to reveal any change %-wise in fuel economy tests. I was very confident that the testing range of error comes in at under 0.5%
Fuel economy driving at 75 MPH was 33.8 mpg
Fuel economy driving at 60 MPH was 40.8 mpg
Fuel economy testing with the Tornado fuel saver showed a 0.0% change.
*Back-to-back test results within 0.1% were impressive in themselves.
Power testing of the Tornado using a VC2000 accelerometer showed a WOT power decrease of 5%
The Elantra showed 111 HP without the tornado and 105.5 HP with it.
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That said, along with my own confidence in my testing methods and equipment, I would not go so far as to say that a "Tornado" device or turbulence generator will not or cannot work on some vehicles and in some situations.
A turbulence device generally increases localized air speed at the sacrifice of decreasing overall air speed. This generally requires more energy to move X-amount of air, and can add a small amount of extra heat energy to the air-charge. Generally, this always reduces the maximum power potential of an engine, assuming that the engine was working well before the addition of the extra turbulence. This condition does not always produce similar results when it comes to vehicle fuel efficiency. Added localized turbulence can have the effect of improving the air/fuel mixing process, and/or change the characteristics of the fuel metering curve of a carburetor. The actual "after" results depend on specific conditions, and the "before" state of tune.
On MPFI engines a turbulence device near the throttle-body can't really affect the fuel mixing in a positive way, though auto manufacturers do use techniques to increase turbulence near and after the intake valve area.
On MPFI engines, a possible benefit of a turbulence device could be either by fooling the calibration of a MAF sensor, or by simply adding enough air-charge restriction that throttle resolution is increased. These effects would tend not to show up during steady-state testing, such as my highway tests above, but could become measurable during transitional type tests, and/or normal daily driving. These two effects could be achieved with simpler modifications, and do not require any sort of "swirling" of the air charge. I have personally measured increases in FE due to altering the MAF calibration by both physical means and by re-calibration. I have also measured FE increases due to an increase in part-throttle resolution.
While I wouldn't personally use a "Tornado" device, I can certainly see where in certain situations it could create conditions that result in a FE improvement.
As for the "professional engineer" at the fuelsaving.info site, I have read through his articles and noticed a few errors on his part, especially when it comes to understanding how combustion efficiency relates to vehicle fuel efficiency. Overall, his site is generally correct, and he seems to mean well, but I don't approve of his assumption that "if he doesn't understand it, then it isn't possible". I also don't like how his presentation would tend to discourage people from trying certain things if they wish to test for themselves. Skepticism is a requirement for scientific progress, but one must be careful that skepticism isn't misused to the point of stifling progress.