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Anonymous
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SCIENCE BEHIND FLUID FLOW...
SCIENCE BEHIND FLUID FLOW...
Q and Nert
You are talking science - so look up these two principles
PV = nRT
and Bernoulli's Principle. (Like the perfume atomizer of victorian era)
I am not saying you are wrong. But look up these principles.
For a given mass volume of air....if squeezed into a smaller opening - air pressure will DROP and air velocity will SPEED up.
So what.
Bernoulli's Principle is what basically causes fuel to be pulled up from the carburator float bowls.
Basically, opening up the INLET of an air box (part going to the air outside) will LEAN out a bike. Why? Air boxes are restrictive or "tight". Tight means that the air box is the most restrictive part of the intake tract into the bike's engine. Remember the air box feeds multiple carburators, and at high RPM's all of the carburators are flowing their max CFM or cubic feet per minute. The INLET opening of the airbox must be able to feed 4 carburators.
Sound is (yes) why airboxes are restrictive. Another way to quiet a bike is to make the airbox volume larger.
Did you know if you make a given air box volume larger, that you may have to rejet for lean condition? Guess what...the same works for EXHAUSTS. If you make the volume of the exhaust canister larger but do not change the tailpipe opening, the bike may lean out also?. This is because the RESERVOIR of air, either in the canister or the airbox, is larger, and remember air is COMPRESSIBLE, so a larger volume is able to Absorp PEAK pressure pulses better, so the engine "thinks" the airbox or canister is LESS RESTRICTIVE.
How do I know - engineer - how else - I played with airboxes and exhaust canisters.
LASTLY - have we covered all we need to know about fluid flow and air boxes? HECK NO.
Brain Teaser: Is the volume of an air box the only thing important to affect tuning of the intake SYSTEM? Answer - NO. Intake tuning is COMPLEX stuff - not totally understood.
EARL/Q/Nert: Take a plastic liter soda bottle - fill it halfway with water and blow across the opening. You'll hear a certain pitch sound. Empty the water out, the pitch will go DOWN. Right? Larger volume, lower pitch. NOW, take the empty plastic bottle and squeeze the center of the bottle flat (pinch it in the middle). Now blow across the bottle again. What happened, the sound will get LOWER for a DECREASED VOLUME of the bottle. How can that be? Who knows the answer?
And so, airbox SHAPE, VOLUME, inlet and outlet opening sizes, shape of the inlets and outlets ALL affect air flow - otherwise known as INTAKE TUNING... TUNING and it's RESONANCE affect the ability of an intake system to flow.
Basically - that is why we just open up the air box some and rejet. The science will drive you mad. - Tony Dieter
SCIENCE BEHIND FLUID FLOW...
Q and Nert
You are talking science - so look up these two principles
PV = nRT
and Bernoulli's Principle. (Like the perfume atomizer of victorian era)
I am not saying you are wrong. But look up these principles.
For a given mass volume of air....if squeezed into a smaller opening - air pressure will DROP and air velocity will SPEED up.
So what.
Bernoulli's Principle is what basically causes fuel to be pulled up from the carburator float bowls.
Basically, opening up the INLET of an air box (part going to the air outside) will LEAN out a bike. Why? Air boxes are restrictive or "tight". Tight means that the air box is the most restrictive part of the intake tract into the bike's engine. Remember the air box feeds multiple carburators, and at high RPM's all of the carburators are flowing their max CFM or cubic feet per minute. The INLET opening of the airbox must be able to feed 4 carburators.
Sound is (yes) why airboxes are restrictive. Another way to quiet a bike is to make the airbox volume larger.
Did you know if you make a given air box volume larger, that you may have to rejet for lean condition? Guess what...the same works for EXHAUSTS. If you make the volume of the exhaust canister larger but do not change the tailpipe opening, the bike may lean out also?. This is because the RESERVOIR of air, either in the canister or the airbox, is larger, and remember air is COMPRESSIBLE, so a larger volume is able to Absorp PEAK pressure pulses better, so the engine "thinks" the airbox or canister is LESS RESTRICTIVE.
How do I know - engineer - how else - I played with airboxes and exhaust canisters.
LASTLY - have we covered all we need to know about fluid flow and air boxes? HECK NO.
Brain Teaser: Is the volume of an air box the only thing important to affect tuning of the intake SYSTEM? Answer - NO. Intake tuning is COMPLEX stuff - not totally understood.
EARL/Q/Nert: Take a plastic liter soda bottle - fill it halfway with water and blow across the opening. You'll hear a certain pitch sound. Empty the water out, the pitch will go DOWN. Right? Larger volume, lower pitch. NOW, take the empty plastic bottle and squeeze the center of the bottle flat (pinch it in the middle). Now blow across the bottle again. What happened, the sound will get LOWER for a DECREASED VOLUME of the bottle. How can that be? Who knows the answer?
And so, airbox SHAPE, VOLUME, inlet and outlet opening sizes, shape of the inlets and outlets ALL affect air flow - otherwise known as INTAKE TUNING... TUNING and it's RESONANCE affect the ability of an intake system to flow.
Basically - that is why we just open up the air box some and rejet. The science will drive you mad. - Tony Dieter
