velocity stack
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
velocity stack
Last week things at work were very slow, so I grabbed some spare stock we had laying around and made a velocity stack for my J’s style intake.
The part is made out of 2024 aluminum.
The part is made out of 2024 aluminum.
Member
Joined: Feb 2004
Posts: 2,451
Likes: 1
From: Pearl City, HI, USA
Re: velocity stack (MadtownSi)
Looks nice, but I don't see it actually doing anything just being stuck in the end of an intake tube like that. It will increase the velocity until it gets to the end of the venturii, then it will just slow back down.
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
Re: velocity stack (beepy)
Think about it this way, the air will speed up as it passes the V.S., this should help bring air into the intake tube faster, then like you said it will slow down once it enters the larger section of the intake tube. Now the intake tube is continually reducing in diameter before it hits the T.B. and this shape should bring velocity back up. All I’m trying to accomplish is increasing the velocity entering the intake tube.
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
I’m not sure if the velocity stack I made is going to do much, I was just an idea I had one night and thought I would try it out. Hell it cost me NOTHING!! Free parts =
Modified by MadtownSi at 2:27 PM 3/29/2005
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
I’m not sure if the velocity stack I made is going to do much, I was just an idea I had one night and thought I would try it out. Hell it cost me NOTHING!! Free parts =
Modified by MadtownSi at 2:27 PM 3/29/2005
Member
Joined: Feb 2004
Posts: 2,451
Likes: 1
From: Pearl City, HI, USA
Re: velocity stack (MadtownSi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">Think about it this way, the air will speed up as it passes the V.S., this should help bring air into the intake tube faster, then like you said it will slow down once it enters the larger section of the intake tube. Now the intake tube is continually reducing in diameter before it hits the T.B. and this shape should bring velocity back up. All I’m trying to accomplish is increasing the velocity entering the intake tube. </TD></TR></TABLE>
Whatever floats your boat. You aren't going to make a perpetual motion machine or a turbocharger without moving parts. Velocity stacks are designed to aid flow through a throttle, but they only work if they are attached directly to the throttle.
Whatever floats your boat. You aren't going to make a perpetual motion machine or a turbocharger without moving parts. Velocity stacks are designed to aid flow through a throttle, but they only work if they are attached directly to the throttle.
Banned
Joined: Mar 2002
Posts: 2,784
Likes: 0
From: CA, USA
Re: velocity stack (beepy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy »</TD></TR><TR><TD CLASS="quote">Velocity stacks are designed to aid flow through a throttle, but they only work if they are attached directly to the throttle.</TD></TR></TABLE>
They improve flow anywhere fluid flow transitions around a corner. The sharp edge at the transision point is responsible for the lousy flow. If the one in the picture was larger, so the hose fit directly onto the small end of it, it would do a much better job.
They improve flow anywhere fluid flow transitions around a corner. The sharp edge at the transision point is responsible for the lousy flow. If the one in the picture was larger, so the hose fit directly onto the small end of it, it would do a much better job.
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
Re: velocity stack (beepy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy »</TD></TR><TR><TD CLASS="quote">
Whatever floats your boat. You aren't going to make a perpetual motion machine or a turbocharger without moving parts. Velocity stacks are designed to aid flow through a throttle, but they only work if they are attached directly to the throttle.</TD></TR></TABLE>
This statement is a big confusing to me because if putting a V.S. after the filter does no good then why would Mugen, ARC and AEM (way back in the day) use them on their intakes??
Whatever floats your boat. You aren't going to make a perpetual motion machine or a turbocharger without moving parts. Velocity stacks are designed to aid flow through a throttle, but they only work if they are attached directly to the throttle.</TD></TR></TABLE>
This statement is a big confusing to me because if putting a V.S. after the filter does no good then why would Mugen, ARC and AEM (way back in the day) use them on their intakes??
Trending Topics
Honda-Tech Member
Joined: Mar 2001
Posts: 6,083
Likes: 0
From: Feeling FOBulous
Re: velocity stack (MadtownSi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MadtownSi »</TD></TR><TR><TD CLASS="quote">
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
</TD></TR></TABLE>
Nice idea Scott
Here's a pic of the old Mugen intake with its velocity stack:
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
</TD></TR></TABLE>
Nice idea Scott
Here's a pic of the old Mugen intake with its velocity stack:
Junior Member
Joined: Oct 2003
Posts: 536
Likes: 0
From: Houston, Texas, USA
Re: velocity stack (MadtownSi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MadtownSi »</TD></TR><TR><TD CLASS="quote">Think about it this way, the air will speed up as it passes the V.S., this should help bring air into the intake tube faster, then like you said it will slow down once it enters the larger section of the intake tube. Now the intake tube is continually reducing in diameter before it hits the T.B. and this shape should bring velocity back up. All I’m trying to accomplish is increasing the velocity entering the intake tube.
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
I’m not sure if the velocity stack I made is going to do much, I was just an idea I had one night and thought I would try it out. Hell it cost me NOTHING!! Free parts =
Modified by MadtownSi at 2:27 PM 3/29/2005</TD></TR></TABLE>
It will for sure do one nice thing. When the air gains velocity and then losses it really fast going from the vs to the large intake pipe, it will lose heat just like air coming out of the charge pipes into an intercooler. By getting a colder charge of air into the engine you will get more power this way.
This is very similar to the Mugen intakes that have a V.S. directly after the filter, or like the ARC intake box that has a V.S. inside the intake box, just before the air enters the expansion tube.
I’m not sure if the velocity stack I made is going to do much, I was just an idea I had one night and thought I would try it out. Hell it cost me NOTHING!! Free parts =
Modified by MadtownSi at 2:27 PM 3/29/2005</TD></TR></TABLE>
It will for sure do one nice thing. When the air gains velocity and then losses it really fast going from the vs to the large intake pipe, it will lose heat just like air coming out of the charge pipes into an intercooler. By getting a colder charge of air into the engine you will get more power this way.
Member
Joined: Feb 2004
Posts: 2,451
Likes: 1
From: Pearl City, HI, USA
Re: velocity stack (BmCRace.com)
My god. Now velocity stacks can be used as refrigerators. Come on people, gain a basic understanding of fluid dynamics. 
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. It is also true than the temperature will reduce in the low pressure section... but it will just heat up right again when the flow slows down. A little piece of metal will not violate physics. It will not by itself add or remove heat, or permanently increase velocity in a pipe.
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. It is also true than the temperature will reduce in the low pressure section... but it will just heat up right again when the flow slows down. A little piece of metal will not violate physics. It will not by itself add or remove heat, or permanently increase velocity in a pipe.
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
Re: velocity stack (beepy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy »</TD></TR><TR><TD CLASS="quote">My god. Now velocity stacks can be used as refrigerators. Come on people, gain a basic understanding of fluid dynamics.
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. It is also true than the temperature will reduce in the low pressure section... but it will just heat up right again when the flow slows down. A little piece of metal will not violate physics. It will not by itself add or remove heat, or permanently increase velocity in a pipe.</TD></TR></TABLE>
I’m no fluid dynamics engineer but if bigger companies, companies that have $$$$ to spend on R&D find it useful to use a velocity stack in the intakes they produce then what is wrong with trying he same idea on another type of intake??
This is a statement I pulled out of a book I have about the old AEM CAI that had a velocity stack just after the filter.
“The air horn in the AEM improves the air flow capacity of the intake tube by keeping the air from making a radical change in direction. If you force the air to turn more then 10 degrees or so, it wants to separate from the surface, tumble and slow down. If the entrance to the tube were flat, some of the air would have to make a 90-degree turn. You’d get a separation bubble around the edges of the entrance all the way around the tube, which effectively reduces the diameter of the intake and therefore reduces flow.”
BTW, no one said velocity stacks can be used as refrigerators.
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. It is also true than the temperature will reduce in the low pressure section... but it will just heat up right again when the flow slows down. A little piece of metal will not violate physics. It will not by itself add or remove heat, or permanently increase velocity in a pipe.</TD></TR></TABLE>
I’m no fluid dynamics engineer but if bigger companies, companies that have $$$$ to spend on R&D find it useful to use a velocity stack in the intakes they produce then what is wrong with trying he same idea on another type of intake??
This is a statement I pulled out of a book I have about the old AEM CAI that had a velocity stack just after the filter.
“The air horn in the AEM improves the air flow capacity of the intake tube by keeping the air from making a radical change in direction. If you force the air to turn more then 10 degrees or so, it wants to separate from the surface, tumble and slow down. If the entrance to the tube were flat, some of the air would have to make a 90-degree turn. You’d get a separation bubble around the edges of the entrance all the way around the tube, which effectively reduces the diameter of the intake and therefore reduces flow.”
BTW, no one said velocity stacks can be used as refrigerators.
OG Fabricator
Joined: Mar 2003
Posts: 1,438
Likes: 0
From: Knoxville, tn, 37912
Re: velocity stack (MadtownSi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MadtownSi »</TD></TR><TR><TD CLASS="quote">I’m no fluid dynamics engineer but if bigger companies, companies that have $$$$ to spend on R&D find it useful to use a velocity stack in the intakes they produce then what is wrong with trying he same idea on another type of intake?? </TD></TR></TABLE>
Many times, companies find it useful in creating income
Many times, companies find it useful in creating income
Joined: Feb 2005
Posts: 967
Likes: 1
From: Carson, CA
Re: velocity stack (MadtownSi)
That particular intake was designed with a particular inlet diameter. Your velocity stack changes the ID on the inlet which may not compliment the rest of the intakes functions properly. I would recomend a large radius (200 degree) lip that goes outside of the intake inlet with a thoat diameter equal to the inlet on the intake.
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
Re: velocity stack (Innovation)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Innovation »</TD></TR><TR><TD CLASS="quote">That particular intake was designed with a particular inlet diameter. Your velocity stack changes the ID on the inlet which may not compliment the rest of the intakes functions properly. I would recomend a large radius (200 degree) lip that goes outside of the intake inlet with a thoat diameter equal to the inlet on the intake.</TD></TR></TABLE>
I actual was thinking about doing this. I have a bigger filter on order witch will allow me to make a new velocity stack that will have an I.D. equal to the I.D. of the intake tube. I think this one will produce better results then my first attempt.
I actual was thinking about doing this. I have a bigger filter on order witch will allow me to make a new velocity stack that will have an I.D. equal to the I.D. of the intake tube. I think this one will produce better results then my first attempt.
Honda-Tech Member
Joined: Feb 2004
Posts: 1,592
Likes: 0
From: not riding any bandwagons in, massachusetts, usa
Re: velocity stack (beepy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy »</TD></TR><TR><TD CLASS="quote">
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. </TD></TR></TABLE>
it is hard to determine whether the purpose of a bellmouth (called a "point sink" in fluid books) is strictly to manipulate pressure/increase velocity or to reduce turbulence. bellmouths have a significant effect on streamlines and are proven to be less turbulent than abrupt edges.
the velocity profiles show that laminar flow has significantly higher peak velocity in the center of a circular conduit than does turbulent flow.. so... is the speed increase resultant of pressure or of turbulence reduction?
when you say "venturi" .. i generally believe those are considered to converge to a narrow and diverge from there rather than simply converge to a constant diameter like a bellmouth. then ofcoarse i suppose you could argue that valve seat is the restriction area and chamber is the diverge.
my point is that bellmouths have proven to make power but who really knows exactly why? theories are based on what experiment results appear to tell us, but its up to the researcher to interperet the results correctly. science is under constant revision.
I agree that a bellmouth can and will reduce turbulence when put on the end of a tube. However, a velocity stack is a venturii, designed to increase flow velocity and decrease pressure, not to smooth out turbulence. </TD></TR></TABLE>
it is hard to determine whether the purpose of a bellmouth (called a "point sink" in fluid books) is strictly to manipulate pressure/increase velocity or to reduce turbulence. bellmouths have a significant effect on streamlines and are proven to be less turbulent than abrupt edges.
the velocity profiles show that laminar flow has significantly higher peak velocity in the center of a circular conduit than does turbulent flow.. so... is the speed increase resultant of pressure or of turbulence reduction?
when you say "venturi" .. i generally believe those are considered to converge to a narrow and diverge from there rather than simply converge to a constant diameter like a bellmouth. then ofcoarse i suppose you could argue that valve seat is the restriction area and chamber is the diverge.
my point is that bellmouths have proven to make power but who really knows exactly why? theories are based on what experiment results appear to tell us, but its up to the researcher to interperet the results correctly. science is under constant revision.
Banned
Joined: Mar 2002
Posts: 2,784
Likes: 0
From: CA, USA
Re: velocity stack (mike_belben@yahoo.com)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com »</TD></TR><TR><TD CLASS="quote">...my point is that bellmouths have proven to make power but who really knows exactly why? </TD></TR></TABLE>
It isn't that hard. The purpose of the velocity stack makes air have an easier time flowing into the inlet. The effective diameter of a simple pipe cut straight off at the end is smaller then its physical size because of how the air pours over the sharp edges. The VS prevents that and allows the full diameter of the pipe to work. Net result: more air flow via less resistance. Any fluid dynamics book covers this.
As applied in the top picture, there will be a net loss in the system because, while the air flows into the VS stack properly, it ends in a sharp edge, causing the air to tumble off the edge. The inside diameter must be the same as the ID of the hose in order to work.
It isn't that hard. The purpose of the velocity stack makes air have an easier time flowing into the inlet. The effective diameter of a simple pipe cut straight off at the end is smaller then its physical size because of how the air pours over the sharp edges. The VS prevents that and allows the full diameter of the pipe to work. Net result: more air flow via less resistance. Any fluid dynamics book covers this.
As applied in the top picture, there will be a net loss in the system because, while the air flows into the VS stack properly, it ends in a sharp edge, causing the air to tumble off the edge. The inside diameter must be the same as the ID of the hose in order to work.
Honda-Tech Member
Joined: Feb 2004
Posts: 1,592
Likes: 0
From: not riding any bandwagons in, massachusetts, usa
you missed the message i was implying in that quote. is it lack of turbulence that makes the power, or is it increased veloicity? you can say one, he can say the other, the evidence can be used to support both. see what i mean?
i posted those photos from fluid books i have read. i didnt mean i was clueless, just that theories change over time. not everything that was believed in a book from 1950 made it into one being taught in 2005. "swirl" was like black magic for 20 years, and people once thought higher flow numbers always made best power. things arent always as they appear.
*edit
btw i am not disagreeing with you. this somewhat illustrates your example.
Modified by mike_belben@yahoo.com at 7:19 PM 3/31/2005
i posted those photos from fluid books i have read. i didnt mean i was clueless, just that theories change over time. not everything that was believed in a book from 1950 made it into one being taught in 2005. "swirl" was like black magic for 20 years, and people once thought higher flow numbers always made best power. things arent always as they appear.
*edit
btw i am not disagreeing with you. this somewhat illustrates your example.
Modified by mike_belben@yahoo.com at 7:19 PM 3/31/2005
Member
Joined: Feb 2004
Posts: 2,451
Likes: 1
From: Pearl City, HI, USA
Re: (mike_belben@yahoo.com)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">The air horn in the AEM improves the air flow capacity of the intake tube...</TD></TR></TABLE>
Yes, the "air horn" is a bellmouth. A bellmouth is not a velocity stack. A velocity stack is a venturii. Look at the original post. There is no 90 degree turn, just a reduction in diameter -- a venturii.
An air horn/bell mouth is a good thing to stick on the end of an intake. A velocity stack belongs attached to something with reduced diameter, ie a throttle, to aid flow past that obstacle.
Yes, the "air horn" is a bellmouth. A bellmouth is not a velocity stack. A velocity stack is a venturii. Look at the original post. There is no 90 degree turn, just a reduction in diameter -- a venturii.
An air horn/bell mouth is a good thing to stick on the end of an intake. A velocity stack belongs attached to something with reduced diameter, ie a throttle, to aid flow past that obstacle.
Thread Starter
Trial User
Joined: Aug 2000
Posts: 396
Likes: 0
From: Madison, WI, USA
Re: velocity stack (kb58)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 »</TD></TR><TR><TD CLASS="quote">
As applied in the top picture, there will be a net loss in the system because, while the air flows into the VS stack properly, it ends in a sharp edge, causing the air to tumble off the edge. The inside diameter must be the same as the ID of the hose in order to work.</TD></TR></TABLE>
This is what I'm trying to make on my next attempt. The next prototype will have an I.D. that will match the current inlet I.D. of my intake. I should have a new part sometime next week.
As applied in the top picture, there will be a net loss in the system because, while the air flows into the VS stack properly, it ends in a sharp edge, causing the air to tumble off the edge. The inside diameter must be the same as the ID of the hose in order to work.</TD></TR></TABLE>
This is what I'm trying to make on my next attempt. The next prototype will have an I.D. that will match the current inlet I.D. of my intake. I should have a new part sometime next week.
Honda-Tech Member
Joined: May 2002
Posts: 10,082
Likes: 2
Re: velocity stack (MadtownSi)
hey what u gonna do with your first piece? i really want that thing on my j's intake. ^^ can i get it off u somehow? it was free for u.. so u have nothing to lose 
and yeah i have question. did vtec sound louder with that velocity stack?
and yeah i have question. did vtec sound louder with that velocity stack?
Honda-Tech Member
Joined: Oct 2003
Posts: 1,521
Likes: 0
From: United States
i do think that the vs on the j's intake with no filter would do some good, i know that i dynoed 4whp higher with no filter on the j's, and im sure it would have been better should i have had a vs on the end (and a little more airflow than sitting still on a dyno, the fans dont simulate actual airflow that great, but you guys knew that)
Joined: Sep 2002
Posts: 440
Likes: 0
From: New Hope, PA, USA
Re: velocity stack (Special B)
Sweet article clippings mike
Madtown i like your flow theory with the j's intake- i guess the only real way to see is with a dyno. Just curious where do you work? What type of machine(s) did you use to create it. Talk about the fab part!
Madtown i like your flow theory with the j's intake- i guess the only real way to see is with a dyno. Just curious where do you work? What type of machine(s) did you use to create it. Talk about the fab part!
Joined: Sep 2002
Posts: 440
Likes: 0
From: New Hope, PA, USA
Re: velocity stack (XLR8 GS-R)
looking at it again the radius (?) design resembles the stacks you can buy now for the jap bikes, except like mentioned earlier those are mounted directly to the carbs or t-bodys.
Thread
Thread Starter
Forum
Replies
Last Post
See Are X
All Motor / Naturally Aspirated
15
Mar 20, 2004 11:39 AM
SpoonboyChoi
Acura Integra
4
Aug 8, 2003 07:54 PM