velocity stacks

[tovar]

Originally Posted by ICU

..but if the length could vary the pressure at the butterfly valve could remain constant.

Which is what you have on newer R6. Also some cars use this.

[tovar]

Originally Posted by ernestmyname

I think of an engine as wanting air. The fact that the butterfly valves limit it's air intake is the only reason the engine doesn't run wide open and asplode.

It limits area, not speed. If you put ram air you get more air in engine without increasing size of intake.

[ratking]

F*** it,.. I don't need no explanation,.. the name is cool enough for me,... velocity stacks!

I'm getting me some...

[warpedsv]

lol

[ernestmyname]

Originally Posted by ratking

F*** it,.. I don't need no explanation,.. the name is cool enough for me,... velocity stacks!

I'm getting me some...

When put in this perspective I'll just stfu..

[neemeth]

Originally Posted by matthumm77

More airflow. Think of a vortex effect. Remember the old trick with the 2liter bottle of water? If you create a vortex with the bottle, the water empties out faster. Same concept. I have them, there is a difference but it is very small. I had some extra cash at the time so I figured why not. Never did a dyno so no facts to support it.

I am not sure if I understand your post correctly. Are you saying that the stacks cause the air to rotate, and create a vortex, as it passes through the stack? Or are you saying that the vortex in your example acts as a velocity stack and allows for an unrestricted air passage through the water? Either way I am not sure if this is a good correlation to the effects of the velocity stacks.
The velocity stacks do not cause a vortex. The vortex that you are talking about is caused by centripetal and centrifugal forces applied to varying densities (water and air). The basic purpose of the stacks is to reduce turbulence, allowing a higher "velocity", resulting in an increase air delivery. A vortex would cause turbulence and slow down the air delivery.

[ernestmyname]

Originally Posted by neemeth

A vortex would cause turbulence and slow down the air delivery.

What you say is BLASPHEMY!!!

[andyauger]

Velocity stacks are not velocity stacks, really. They are acoustic tuning horns. The effect is the same (in reverse) as tapered exhausts. Since they are tuned devices they tend to work in a fairly limited RPM range. The benefit on street bikes is negligible, and sometimes there is a deficit rather than a benefit. Today's intake boxes are designed to provide acoustic tuning over the widest RPM range practical, generally around the torque peak. They also are designed so they don't impede air flow by "bad" acoustic pulse timing.

For performance the fattest torque curve possible is best. Peak horsepower is not part of peak performance. Take a look here:
http://spreadsheets.google.com/ccc?k...ya1Q3SEE&hl=en

[Jay V]

A friend of mine builds race engines and spends a lot of time on a flow bench and dyno. When I asked him about getting more power by altering the length of intake stacks he said he has found that stacks do not add or subtract power, they just move it up or down in the powerband.


Jay

[matthumm77]

Originally Posted by neemeth

I am not sure if I understand your post correctly. Are you saying that the stacks cause the air to rotate, and create a vortex, as it passes through the stack? Or are you saying that the vortex in your example acts as a velocity stack and allows for an unrestricted air passage through the water? Either way I am not sure if this is a good correlation to the effects of the velocity stacks.
The velocity stacks do not cause a vortex. The vortex that you are talking about is caused by centripetal and centrifugal forces applied to varying densities (water and air). The basic purpose of the stacks is to reduce turbulence, allowing a higher "velocity", resulting in an increase air delivery. A vortex would cause turbulence and slow down the air delivery.

Pen Sate seems like a pretty smart school

I just assumed that was what happens. It seemd right at the time I was typing it. I see your point with the turbulence. The bottom line I guess is more air going into the engine.