velocity stacks - Suzuki SV650 Forum: SV650, SV1000, Gladius Forums

warpedsv · 11-03-2009, 08:22 PM

what is the main purpose for velocity stacks and are they worth the 112 bucks or no?

tovar · 11-03-2009, 08:32 PM

Word velocity should give you answer.

matthumm77 · 11-03-2009, 08:33 PM

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.

mysql · 11-03-2009, 08:35 PM

http://en.wikipedia.org/wiki/Velocity_stack

ernestmyname · 11-03-2009, 08:47 PM

These would only be useful at WOT, right?

tovar · 11-03-2009, 08:49 PM

No, depends on length.

ernestmyname · 11-03-2009, 08:50 PM

seems like if the air flow is being restricted by the throttle, there is no benefit to be had..

I could be wrong. Explanation of why this would be helpful at mid throttle would be nice.

tovar · 11-03-2009, 08:54 PM

Longer intake track improves mid range compared to shorter one.

ernestmyname · 11-03-2009, 09:01 PM

you're killing me here.

why?

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.

If you are limiting the air coming in with a butterfly valve, what benefit is having the air come in 'straighter' if you are just going to F it up with a butterfly valve??

ICU · 11-03-2009, 09:20 PM

This is what I understood from the wiki page that I just read...

One of the purposes of the stacks are to smooth out the airflow for the a more even and laminar flow in. with out the stack you have an abrupt change in wind direction and velocity which causes a "pinching" of the actual airflow into the pipe. This pinching will have a higher probability of causing turbulant flow inside the pipe and non uniform air flow past the butterfly valve...therefore making the air to fuel mixture unsteady.

Also, the length of the tube will cause a variance in pressure at the point in which air bypasses the butterfly valves. I'm guessing (this is assuming that the pipe length can vary while riding...I may be wrong so take this with a grain of salt) that because the bike is never at the same velocity at any one point in time, that velocity outside the stack results in differrent initial pressures...therefore you have different pressures at the butterfly valve, if the length was constant...but if the length could vary the pressure at the butterfly valve could remain constant.

I'm no expert...but that is my best guess

11-03-2009, 08:22 PM	#1
warpedsv Member Join Date: Jul 2009 Location: trenton, MI Bikes: sv 650 Miles Kms: 4000 Posts: 146 iTrader: (3)	velocity stacks what is the main purpose for velocity stacks and are they worth the 112 bucks or no?

11-03-2009, 08:32 PM	#2
tovar Senior Member Join Date: Jul 2009 Bikes: moped Posts: 1,291 iTrader: (0)	Re: velocity stacks Word velocity should give you answer.

11-03-2009, 08:33 PM	#3
matthumm77 Senior Member Join Date: Jun 2008 Location: Colorado Springs Bikes: SV650/S, 2008 Miles Kms: 5k+ Posts: 585 iTrader: (2)	Re: velocity stacks 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. __________________ Life is to short. Use your time wisely and never let someone waste it.

11-03-2009, 08:35 PM	#4
mysql Member Join Date: Oct 2009 Location: Tampa Bikes: 2006 SV650S Posts: 118 iTrader: (0)	Re: velocity stacks http://en.wikipedia.org/wiki/Velocity_stack

11-03-2009, 08:47 PM	#5
ernestmyname Site Supporter Join Date: Jun 2008 Location: Clemson, SC Bikes: 2005 sv650 Miles Kms: ~miles*.6214 Posts: 1,120 iTrader: (7)	Re: velocity stacks These would only be useful at WOT, right? __________________ Best vid on the internets: here

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11-03-2009, 08:49 PM	#6
tovar Senior Member Join Date: Jul 2009 Bikes: moped Posts: 1,291 iTrader: (0)	Re: velocity stacks No, depends on length.

11-03-2009, 08:50 PM	#7
ernestmyname Site Supporter Join Date: Jun 2008 Location: Clemson, SC Bikes: 2005 sv650 Miles Kms: ~miles*.6214 Posts: 1,120 iTrader: (7)	Re: velocity stacks seems like if the air flow is being restricted by the throttle, there is no benefit to be had.. I could be wrong. Explanation of why this would be helpful at mid throttle would be nice. __________________ Best vid on the internets: here

11-03-2009, 08:54 PM	#8
tovar Senior Member Join Date: Jul 2009 Bikes: moped Posts: 1,291 iTrader: (0)	Re: velocity stacks Longer intake track improves mid range compared to shorter one.

11-03-2009, 09:01 PM	#9
ernestmyname Site Supporter Join Date: Jun 2008 Location: Clemson, SC Bikes: 2005 sv650 Miles Kms: ~miles*.6214 Posts: 1,120 iTrader: (7)	Re: velocity stacks you're killing me here. why? 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. If you are limiting the air coming in with a butterfly valve, what benefit is having the air come in 'straighter' if you are just going to F it up with a butterfly valve?? __________________ Best vid on the internets: here

11-03-2009, 09:20 PM	#10
ICU Member Join Date: Jan 2009 Location: VA Bikes: 2 wheeler Miles Kms: Don't look down too often to check Posts: 69 iTrader: (0)	Re: velocity stacks This is what I understood from the wiki page that I just read... One of the purposes of the stacks are to smooth out the airflow for the a more even and laminar flow in. with out the stack you have an abrupt change in wind direction and velocity which causes a "pinching" of the actual airflow into the pipe. This pinching will have a higher probability of causing turbulant flow inside the pipe and non uniform air flow past the butterfly valve...therefore making the air to fuel mixture unsteady. Also, the length of the tube will cause a variance in pressure at the point in which air bypasses the butterfly valves. I'm guessing (this is assuming that the pipe length can vary while riding...I may be wrong so take this with a grain of salt) that because the bike is never at the same velocity at any one point in time, that velocity outside the stack results in differrent initial pressures...therefore you have different pressures at the butterfly valve, if the length was constant...but if the length could vary the pressure at the butterfly valve could remain constant. I'm no expert...but that is my best guess

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