Motorized bicycle Mad Scientist Lab test - Boost Bottle
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Dec 26, 2007
Scottsville, VA
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.



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