Mad Scientist Lab test - Boost Bottle

HI All,

As many of you may know, the boost bottle's purpose is to enhance low to
mid RPM power....the theory behind this can be readily located on the net but in a nutshell, the boost bottle helps low to mid range power by basically smoothing the flow of the air fuel mixture into the carb and preventing it from reverting back into the carb / intake tract when the piston closes off the intake port abruptly.

Much research has been done to determine the optimum size for the bottle
but it seems that the optimal size for the bottle and connections (yes you must include the volume of the fittings and hose which connects actual bottle to the intake manifold) is such that the engine's displacement must be matched to the volume of the bottle/hoses/fittings.

Out of curiosity, I decided to open up my lab equipment (photos attached) to
determine the actual volume of the boost bottle and fittings to see how closely it matches engine displacement.

The bottle I own (yellow item in pic) came from Boost Bottle Industries. It is
Rated as the 70/80 CC kit.

Because the bottle is unvented (only 1 entrance and exit), it would be difficult to pour the liquid (in this case water) out of the bottle (without it spilling and throwing off the measurements) to measure the bottle's volume.....What I did was a 2 step process. First, I filled the bottle only with water. Then I used the hypodermic syringe to extract the water from the bottle and squirt it into the graduated cylinder.

When all was said and done, the bottle itself had a volume of approximately 67 CC.

Next, to measure the volume of the provided fittings, I pushed both hose barbs as far as they would into the supplied tubing.....I filled the entire assembly with water and then poured its contents into the graduated cylinder to measure its volume. This was found to be 17 CC.

In summary, as provided by the factory, the bottle and fittings have a volume of approximately 84 CC....What does this suggest?....the measurements seem to indicate that if one is looking to optimize boost bottle efficiency
(assuming that optimal is exactly matching the engine's displacement) that one would need to run a minimal length of hose....Furthermore, it may be of benefit actually tap another port to the bottom of the bottle (use a nipple along the long edge of the bottle) to minimize hose length when connecting the bottle to the engine manifold. The remaining factory hole could be filled with a bolt of known displacement (of course must be custom made for length for each different engine brand) that can be used to adjust the system volume so that it exactly matches the engines displacement.

Is such accuracy really needed?....well, given the degree of accuracy and engineering required to make an effective tuned pipe / expansion chamber it would seem to suggest tha the answer be "yes"....After all, we are basically tuning the intake system so to speak.....a lot of wave theory applies to both intake and exhausts.

Will the boost bottle work as is?.....I have heard more good things than bad but I plan on doing a test of all this when my custom intake manifold is finally done.

Hope this helps all you tinkerers out there!....Comments, questions, and other findings / views are always welcome.



Andrew

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wow andy. i am wondering if the problems people have with the idle which is the only draw back i have heard about the boost bottle if it was identical in volume those problems would be gone. i am looking forward to hearing more and can't wait till you have a tuned pipe. my checkbook is ready soon as you do my friend for i want one

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I have heard both positive and negative comments on boost bottles. I suppose I would have to try one first hand to draw a conclusion.

Dan

Andy, the last time I looked at boost bottles (on Ebay) they offered a manifold that has been tapped.

HI Red,

yes, I saw the manifolds....that would be great for people who want a quick and easy way to attach a boost bottle...It looks to be modeled after the factory piece which has some serious flow restricting bends in it tho.....I have been tinkering with making a manifold that would increase power by being of the proper tuned length and having
freer flowing smooth bends (also, by offsetting the carb to the side, this would allow many more people to use a freer flowing better air filter such as the oiled open element K&N style filters....(possibly an optional cover for those who ride in the rain).
Getting there slowly but surely.
Andrew

Hi Paul,

While I have not yet hooked up my boost bottle, it is a common for the idle speed to increase fairly substantially when using the boost bottle. This ultimately requires an adjustment to the idle speed screw (RPM's increase because the air/fuel flow is "smoother" and the reversion wave is lessened allowing for more air/fuel into the engine for a given thottle setting)).

The other problem I have heard with the boost bottle, is when the air/fuel in the boost bottle condenses into just a liquid fuel and eventually runs back into the intake manifold.....obviously this can cause problems with running (and possible even after running depending on the amount of fuel pooled) and is one of the main reasons the outlet of the boost bottle must or should be pointed down to the intake manifold....More often than not this is not done and problems can result.

In thinking of the problem more thoroughly, perhaps the ultimate shape for the boost bottle is a somewhat stocky triangle (narrow in profile...relatively squat in height) with the outlet at the very point on the bottom.....this would ensure that any condensed fuel in the bottle itself would always drain out almost immediately....something that the current cylindrical bottle shape may be a little slow at doing at times unless mounted in the vertical position (which for most practical purposes will not happen due to the need to commonly mount it to the top tube of the bike).

Andrew

Hi Dan,

If / when you try the boost bottle, please let us know your results....Then more info we have the better things get! ;-)

Have fun tinkering!

Andrew

Guys I've made a few boost bottles and my finding are well I'm taking them off. I've even made an adjustable one varied form 40 to 90cc and I can't find anything that great by using one. Sure it will idle with the idle screw turned out more and they make a funny sound when you come off the throttle. To me the idle will stay high then go to so slow a idle speed the engine will die. I've had long connection tubes and short. Big fat and short long ones. and in different cc ranges.
Some of you may like them. I don't, to me I'm glad I made my own and didn't spent the bucks to find out what I did. If you want to argue send me your bottle I'll try it and let you know what I think and teturn it to you I'll pay return shipping. You want to try mine, send me your address and the money to cover the postage, you can have mine. I still have 3 and will soon be cutting them up to make something else.
That is my opinion only, they may be just the ticket for you.
Norman

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I have to admit I bought one. I really didn't see an increase in power, However I didn't see a decrease in performance either.
Is there a certain length you recommend the hose I should? Here's a picture of mine. (After my 40+ mile ride in the rain)
Do you think it's too short?

Thanks...

Well I'm going to weigh in with my bike scares me at full throttle, I don't want any more speed.

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