Boost Bottle?

this is just to clear some things up and answer some questions

It's function is to absorb & release pressure pulses within the intake vein, assisting engine breathing. Now an explanation of exactly what goes on involves a lot of physics and a good understanding of fluid dynamics & pressure zones, but can be explained rather easily. During the intake stroke, air is sucked through the intake manifold and into the port at a considerable velocity. Because of this velocity, the air is said to have relative inertia. Now, when the intake valve closes, the kinetically charged air suddenly has nowhere to go, creating a high-pressure area. Naturally, the air wants to release its pressure in the easiest way possible, so it tries to shoot back out the way it came, creating a pressure wave in the opposite direction we want it. Then no sooner dose the wave begin to travel, the intake valve suddenly opens again leaving the motor to try and pull the pressure wave back in again. This dramatically effects low RPM, wastes energy and kills low-end performance. Now the same engine, but with a BOOST BOTTLE. Air goes whistling down the manifold until the intake valve closes. The air, still all charged up with energy tries to escape back up the manifold but is met with a small port that has a residual vacuum. This vacuum being caused by the previous suction of the intake stroke, sucks most of the pulse inside the Boost Bottle, storing much of the pulse’s energy. The intake valve then suddenly opens, creating a low-pressure area outside of the Boost Bottle. The gasses then shoot out of the Boost Bottle, directly into the intake system as a pressure pulse, instead of having to be pulled in by the piston. More air is then also pulled in from the manifold to completely fill the cylinder… Thus giving you an additional boost of power

any objections

I object!! Will the bailiff please restore order in the court!!

its gonna rain!

A "theory" on boost bottles....
2 strokes are very sensitive to intake and exhaust conditions since their simple passive design relies heavily on external components. The exhaust pipes are tuned and equipped with divergent and convergent nozzle sections to create a slight vacuum immediately after exhaust and a slight pressure right before the exhaust port closes. This helps to clear out exhaust gasses and to pull extra fuel/air through the chamber, then the reflected sound pressure wave pushes some of the extra fuel/air back into the cylinder, creating a slight supercharge. The exhaust pipe tuning has a very significant effect, approx. 10%-40% power gains for most engines, however, a mismatched exhaust can also reduce power.

Boost bottles are more controversial with regards to performance gains. If the bottle is properly matched to the engine, it is likely that some gain in performance can be measured, but these gains are usually insignificant, perhaps 1-3 % peak under certain load and rpm conditions.

Boost bottle theory:
All 2 stroke engines equipped with reed valves tend to spit back a little of the fuel air mixture sucked into a chamber. The boost bottle stores this small amount of fuel/air in a tank along with additional air. After one chamber spits back a bit of the mixture, the other is just starting its intake, and boost bottle supporters claim the spitback from one chamber can pressurize the bottle slightly and force more mixture into the other chamber. Others claim that the sudden stop of flow of mixture into one engine chamber creates a pressure wave that would bounce back up the intake pipe unless it had a boost bottle to enter and pressurize, and the bigger chamber instead of a crossover tube reduces flow resistance between carbs.
There are numerous other theories and claims regarding boost bottles, some are at least loosely based on scientific principles, but most of the gains would be slight and only at a few discreet operating points and rpm ranges.

In conclusion: Properly matched boost bottles do produce some (barely) measurable gains over certain rpm ranges, but nothing really significant. Just enough to legally verify that it does produce a gain.

Most of the boost bottle theory available on the internet is usually written or altered by people trying to sell boost bottles, so I wouldn't put too much faith in it. I don't know of any textbooks or sources that would contain scientific data - I don't think the performance gains have been significant enough to attract any serious research interest.

The boost bottle probably won't hurt performance, and there might be some minor gains under a few situations, but I wouldn't recommend buying one unless you simply liked the way it looked on the bike or ATV.

good read there

you make a valid statement and an good point from my experince juice box vs boost bottle is what we should be talking about ive had an ada juice box for 2 years and its been great my revs are cleaner and my rpm increased on a slightly modified cat eye motor the juice box i think is more valid than the boost bottle i say as ive seen when i had the filter off and the wheel in the air ive hit the throttle fast and let out and you see this cloud com out the carb with the juice box it wasnt so common or was hard to tell im not sure about you guys but take off yuor filter and look inside you see the icky oil thats the pressure wave crrying the gas out the intake and making your fillter greasy so maybe thess boost bottle guys have a point. although i think the huice box is more efficient. these i believe have more of an effect on piston port motors than on reed inducted systems. just my ten cents.
what say you?

always better to gain just a bit than none at all i think

Now a juice box is to me a different animal. Same theory I suppose, but at least a juice box can actually lengthen the intake tract length. Without going into a huge rant about it, anybody who has played with varying lengths of v-stacks on their full size bike knows. Altering the intake tract length changes the hit of powerband. Sometimes dramatically. (And not always as expected).
Generally speaking, longer intake runners perform better in the lower RPM range, and shorter runners are better up top.

speaking of vstacks on bikes, here is a couple discussions about that animal, they can help or they can hurt.. getting the correct tuned length is the key to success:

http://www.fireblades.org/forums/hon...rts-added.html

http://www.fireblades.org/forums/hon...-advancer.html

i think a juice box is worth more than the boost bottle my writup is more for juice boxes anyway. wat do you think box or bottle?

i like juicy fruit gum.. its quite tasty

any body try this part yet? http://www.davesmotors.com/store/product1228.html

I have the cateye version on my wifes bike. Just a huge chunk of metal with a threaded hole in it. Nothing special as far as I am concerned.

cat eye version? hmm never seen it besides you can jus swirl port da carb

Same thing, just different bolt pattern.
Swirl port a Walbro barrel carb? No thanks, I'll pass on that one.

not barrel carb a butterfly valve carb thats an uprgrade on its own puts many stockers to shame throttle response is always sharper with a walbro butterfly valve carb!!!!!!!!!!!!!!!!

Our stock cateye carb is a barrel carb. No aftermarket carb on it. Not necessary, since it is the wife's bike. She was happy that I swapped her engine into an X1 frame, and done deal.

Also throttle response is much better if you get a cable that will actually allow the slide to open fully. On every stock cateye / X1 or X2 I have seen, at full throttle, the slide isn't even close to rotating open far enough. Fit a proper size cable and it is a whole different ballgame. Bike actually has a bit of gittyup.

found this info:


Much controversy swirls throughout the internet on boost bottles. So I decided to do some research on these so called performance parts.

First I must state that you can believe what you want in regards to this article. This is written from data gained from legitimate sources and not lame ebay dealers trying to hawk something for a penny and charging $30 for shipping.

What exactly is a boost bottle anyways? Simply put it is a bottle with a hose that connects to the intake.

What are they for? Sellers will tell you they will help you make a ton of horsepower just by screwing one of their premade bottles onto your bike and drilling a hole into your intake. How much is a ton of horsepower? I've seen claims up to 5HP gains.

What do they do? If you read my article on how a two stroke works then you will understand that in a two stroke (reed type), there are no valves to open or close. Essentially at some point in the pistons motion there is a completely open system. Straight through from carb to pipe with no resistance.

Of course since you read my article on two stroke pipes you would also know that a pipe on a two stoke is designed to push the air/fuel charge (charge from now on) back into the head to be burnt.

A boost bottle essentially works on the other end. When the piston comes down it creates a force which pushes the chage outwards in all directions. On one end is the pipe, on the other end the carb. This creates essentially a pulse against the back of the reeds.

A boost bottle works by simply sitting there. When the cylinder goes up and air is pulled in, there is a vacuum at the bottom of the hose for the boost bottle. This causes the bottle to basically empty itself. When the cylinder goes down (without a bottle) the charge pushes against the back of the reeds and cannot go anywhere else. With the boost bottle this charge is able to enter into the bottle as it is essentially empty. Then it empties itself on the next motion of the piston.

Now you basically understand the theory of how it works. So who came up with the idea of a boost bottle and what were they smoking? Well, believe it or not it was Yamaha. You can take a look at Modification of Two-Stroke Engine Intake System for Improvements of Fuel Consumption and Performance through the Yamaha Energy Induction System' by Noriyuki Hata, Takeo Fujita and Noritaki Matsuo, SAE Paper No. 810923 (Sept. 1981).

The system is called the Yamaha Energy Induction System or YEIS. So now you're thinking this isn't just junk science? You'd be right.

So where do the issues come in and why don't they work? Because no one that makes them knows how to make them apparently. The boost bottle has to be at least as big as the cylinder itself, and the hose has to be at least as big as the throttle opening at the intended RPM you want the bottle to work at.

Take a look at some of the boost bottles out there and you'll see hoses so small an ant would suffocate if it tried to breathe through it.

So should we break out some math? I know you guys just love the math I throw at you.

Code:
Calculated Volume = ((Hose Diameter (mm)/20)^2*PI() / (((RPM/60) *2*PI() / (Speed Of Sound (meters/second)*100))^2 * (Hose Length (cm)+1.57 * (Hose Diameter (mm)/20))))

Calculated RPM = (((Speed Of Sound (meters/second)*100) / (2*PI())) *Square Root ((PI*(Hose Diameter (mm)/20)^2) / (Volume (cc's) * (Hose Length (cm) + 1.57 * (Hose Diameter (mm)/20))))) * 60

Calculated Hose Length = (((Hose Diameter (mm)/20)^2 * PI()) / (Volume (cc's) * ((2*PI() * RPM / 60 / (Speed Of Sound (meters/second) * 100))^2))) -((Hose Diameter (mm)/20) * 1.57)
WOW! If you're lost now, I can't blame you. But as you can see the math shows that any slight change will affect how your boost bottle works. So any old boost bottle off the shelf probably won't be right for your bike, bike setup or application.

I must also note that these boost bottles only really make a difference at the lower end of the RPM range. They could be designed to help at top RPM ranges but they would have to be HUGE.

Now that that's all settled, do boost bottles really do anything? Of course they do, otherwise Yamaha wouldn't put them on their production bikes. But the difference here is that while a boost bottle may give you a slight increase in performance, are you really going to notice that on your 2.5HP cag? Not really, but you might experience some improvement in throttle response at the tuned RPM range (as with the math above).

And to make life a little easier, I've attached an Excel spreadsheet you can use to do the calculations on your own boost bottle.

This article was written by Bruce Peresky for pocketbikeforum.com. Copying is permitted provided you give credit to http://www.pocketbikeforum.com

Hello,

You seem to ask me these questions but them answer them yourself..... I do not understand.

I am no stranger to your math quote. (wasn't lost one bit) Yes, some manufacturers use small hose in an effort to save money. We use large tygon tubing with a good 1/4" for better interia transfer. In fact, I teach hands on classes at MMI here in Orlando, FL. (And I am pretty sure I understand how a expansion pipe works... (I have helped R&D them myself) I know all bike engines....Not just chinese pocket bike reed engines. If you are ever in the area and want to stop by, or even enroll in some informative classes, please let me know. Or click here for more info: http://www.uticorp.com/default.aspx?tabid=256 and click on student information. Please visit www.bis-racing.com for additional boost bottle info. yes, we sell on ebay too. But charge a low price for the actual ebay insertion asking price.. By doing so, we save money on Final value fees, and pass the savings onto you. Ebay can be used as an advertising tool. We sell only around 10% on eBay. The rest in our store and online.