## Re: Booster Bottles?

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• ... *Hehe appreciate your flippant physics lesion. Question is how much energy or density an everyday vortex can concentrate. This is a side line ponder but
Message 1 of 5 , Feb 23, 2012
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Whip tips don't make dense vortices.  The reason there is a noise is that part of the whip exceeds the speed of sound.  The energy you put into the whip by flicking the whip handle is constant so as the wave travels down the length of the whip the amount of mass that is being moved decreases to zero, giving the wave an accelerating velocity as it has less mass to move.  Near the end of the whip the velocity turns supersonic and we hear the sonic boom.  I'd think it is a very inefficient conversion of energy to move one's whole arm quickly just to make a noise.  If it was not we'd have hundreds of miniature cowboys positioned just outside each engine bellmouth cracking their whips like crazy to increase induction efficiency.

*Hehe appreciate your 'flippant' physics lesion. Question is how much energy or density an everyday
vortex can concentrate. This is a side line ponder but super sonic bodies also shed vortexes besides
sending out shock waves.  No question the butterfly groove ain't for us but would like to know what
its doing to air flow as very similar to what is done to fine tune idle with bypass air.channel. Cracking
butterfly would seem another way as mentioned.  Bullwhip physics look see.
http://math.arizona.edu/~goriely/Papers/2003-PhysD%28whip-waves%29.pdf

They work on the well known Helmholtz resonant chamber principle and act to help fill a midrange hole in the torque curve at particular intake stream velocities.  It's just like blowing over the mouth of an empty bottle and getting a resonant tone to generate.  Most people completely misunderstand how they work, just do a 'boost bottle' web search and you'll read all sorts of weird things.  Usually you won't see them on well developed race engines as there are better ways to accomplish it, like proper intake and exhaust design.  I think you see them in some production bikes because of the emissions/noise hurdles that manufacturers have to jump through.

*I'm trying to grasp the whole scope of this resonance phenomena. Your blown over bottle mouth
sound is a useful image for me both on these bottle and other places.   I think accelerator pumps
and longer intake tracks and hi rpm nullify benefit but can help those tiny thrift bikes a bit in pits
and urban paths. Motobicycles can go too fast for their cheap type wheels unless upgraded.

My take is that any improvements to a well developed system like an ICE will need to be well explained by generally accepted engineering principles and/or proven by carefully controlled tests.  The explanations of most of these DIY mileage guys fall way short of anything reasonable.  The technical rigor of their 'results' is nonexistent.  They are just easy money schemes looking to defraud the ignorant.

Chris Cosentino

*Its not easy to get full proof of everything that's mildly or intermittently beneficial
so both easy to scam as well and over look opportunity. Just because this groove
can't perform as advertised don't mean its effect can't be used somewhere else.
http://www.princeton.edu/~asmits/Bicycle_web/blunt.html

hobot

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