Is this a velocity stack??
Originally Posted by punish_her
Show me proof that the intake produces an active sinus wave that actively compresses air in a standard OEM intake system, and I will consent that I am mistaken. Not the parabolic opening smoothing air flow, not any related to venturi/ or lack there of but a true pressurized stacking due to sinus waves and not the air being rammed in.
The diffrence is the setup.
The diffrence is the setup.
Variable Length Intake Manifold
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Variable Length Intake Manifold (VLIM) is an automobile engine manifold technology. As the name implies, VLIM can vary the length of the intake tract in order to optimize power and torque, as well as provide better fuel efficiency.
There are two main effects of variable intake geometry:
* Swirl - Variable geometry can create a beneficial air swirl pattern in the combustion chamber. The swirls help distribute the fuel and form a homogeneous air-fuel mixture which ignites without engine knocking. At low rpm, the speed of the airflow is increased by directing the air through a longer path with limited capacity, but the shorter and more capable path opens when the load increases so that the greater amount of air can enter the chamber. In DOHC designs, the air paths are often connected to a separate intake valves so the shorter path can be excluded by inactivating the intake valve itself.
* Pressurization - A tuned intake path can have a light pressurizing effect similar to a low-pressure supercharger due to Helmholtz resonance. However, this effect only occurs over a narrow engine speed band. A variable intake can create two or more pressurized hot spots, increasing engine output.
Many automobile manufacturers use similar technology with different names. Another common term for this technology is Variable Resonance Induction System (VRIS).
* Audi - 2.0*L I4, V6, V8
* Alfa Romeo - 2.0 TwinSpark 16v - 155 ps(114 kW)
* BMW DIVA
* Ferrari - 360 Modena, 550 Maranello
* Ford DSI (Dual-Stage Intake) - on their Duratec 3.0 liter V6, 2.0 liter Zetec four, and it was also found on the Yamaha V6 in the Taurus SHO.
* GM Daewoo - DOHC versions of E-TEC II engines
* Honda - Integra, Legend, NSX
* Hyundai - XG V6
* Jaguar - AJ-V6
* Mazda VICS (Variable Intake Control System) is used in the Mazda B engine family of straight-4, and VRIS in the Mazda K engine family of V6 engines. An updated version of this technology is employed on the new Mazda Z engine, which is also used by Ford as the Duratec.
* Mercedes-Benz
* Mitsubishi Cyclone is used on the 2.0L I4 4G63 engine family.
* Nissan V6 and V8
* Opel TwinPort - modern versions of Ecotec Family 1 and Ecotec Family 0 straight-4 engines; a similar technology is used in 3.2*L 54° V6 engine
* Peugeot 2.2*L I4, 3.0*L V6
* Porsche VarioRam - 964, 993, 996, Boxster
* Renault - Clio 2.0RS
* Toyota T-VIS - (Toyota Variable Intake System) used on the 4A-GE family, notably in the MR2
* Volkswagen - 1.6*L I4, VR6, W8
Retrieved from "http://en.wikipedia.org/wiki/Variable_Length_Intake_Manifold"
More worthwhile reading on ram manifolds for production cars:
http://www.autozine.org/technical_sc...h_engine_2.htm
Note that the Nissan V6 is listed among those using ram technology.
http://www.autozine.org/technical_sc...h_engine_2.htm
Note that the Nissan V6 is listed among those using ram technology.
Yet another example:
As the valves open and close, letting in charges of air, resonances are created. Many things create resonances, such as the valves rapidly opening and closing or the pistons moving back and forth. When an intake valve closes, for example, it sends a wave of compressed air back into the intake, in the reverse direction. This wave of air rebounds inside the intake, and when timed perfectly will return to the valve just as it is again opening. This rebound effect can create as high as a 7psi intake charge just from the inertia of this rebounding air- as high as some superchargers.
This is another form of valve tuning, and it works on the principles of Helmholtz Resonance. A static intake manifold can only be optimized for one specific RPM, so it is beneficial to develop a method to vary the intake length and/or volume. The resin intake manifold that Mazda used to create their 2.3l engine has a valve that changes the volume of the intake runner pipes, changing the resonance frequency of the intake inertial charge. The switchover occurs rather discretely at 4500rpm. Each state is tuned to return a wave of pressure to the intake valve at a different RPM.* These two intake runners are switched at a certain RPM, and create a supercharger-like effect on the intake.* This allows Mazda, combined with the variable intake timing, to get a relatively broad torque band, even if not as broad as some VTEC engines. Harnessing and optimizing engine resonances is a fundamental and essential part of engine design, as it allows efficient transfer of air. The 9000rpm RX-8 actually has a three chamber variable inlet design!* Mazda calls their multi-chambered intake a VIS (Variable Intake System), though they are more generally called a VLIM (Variable Length Intake Manifold).
As the valves open and close, letting in charges of air, resonances are created. Many things create resonances, such as the valves rapidly opening and closing or the pistons moving back and forth. When an intake valve closes, for example, it sends a wave of compressed air back into the intake, in the reverse direction. This wave of air rebounds inside the intake, and when timed perfectly will return to the valve just as it is again opening. This rebound effect can create as high as a 7psi intake charge just from the inertia of this rebounding air- as high as some superchargers.
This is another form of valve tuning, and it works on the principles of Helmholtz Resonance. A static intake manifold can only be optimized for one specific RPM, so it is beneficial to develop a method to vary the intake length and/or volume. The resin intake manifold that Mazda used to create their 2.3l engine has a valve that changes the volume of the intake runner pipes, changing the resonance frequency of the intake inertial charge. The switchover occurs rather discretely at 4500rpm. Each state is tuned to return a wave of pressure to the intake valve at a different RPM.* These two intake runners are switched at a certain RPM, and create a supercharger-like effect on the intake.* This allows Mazda, combined with the variable intake timing, to get a relatively broad torque band, even if not as broad as some VTEC engines. Harnessing and optimizing engine resonances is a fundamental and essential part of engine design, as it allows efficient transfer of air. The 9000rpm RX-8 actually has a three chamber variable inlet design!* Mazda calls their multi-chambered intake a VIS (Variable Intake System), though they are more generally called a VLIM (Variable Length Intake Manifold).
punish-her,
Maybe what you are talking about has nothing to do with automotive applications at all.
For ram charging/pressure wave tuning, there is no requirement that the pipes be straight. As a matter of fact, in the real world, I can't think of any intake systems that don't have at least one bend in them and most have more.
This same tuning technique is also used in exhaust systems and again, not one straight system in the real world but exhaust it beyond the scope of this thread.
Also, on a different note
Nobody as far as I have seen is talking about "Ram Air" and it's not relevant to this thread. Ram charging/pressure wave tuning (or what you call stacking) is an entirely different intake subject.
Chris
Maybe what you are talking about has nothing to do with automotive applications at all.
For ram charging/pressure wave tuning, there is no requirement that the pipes be straight. As a matter of fact, in the real world, I can't think of any intake systems that don't have at least one bend in them and most have more.
This same tuning technique is also used in exhaust systems and again, not one straight system in the real world but exhaust it beyond the scope of this thread.
Also, on a different note
Ram air is only efficient and effective when air is being pushed into the intake at a rate faster than the engine consumes it."
Chris
Originally Posted by punish_her
Look carfuly at the verbage. The irregularities are every thing in the intake from the individual openings in the plenum out to the parabolic opening in question. Including the MAF and all the bends. The interior surface is too complex to create an active sinus wave that will compress the whole length of the intake. The wave will refract off any and every irregularity and break up the wave.
Thats why in the site: http://www.velocity-of-sound.com/vel...ity_stacks.htm you see all of the stacks straight. The wave travels the length of the tube and when it hits the parabolic opening it will reflect back into the tube. This rearward reflection is the action that compresses the air. The reason why the specific length is tuned for a specific power band is due to the speed in which the wave reflects back down the length of the tube. They are actualy their most efficient at there tuned RPM Region because the pressurazation is in sync with the intake stroke.
Ram air is only efficient and effecticve when air is being pushed into the intake at a rate faster than the engine consumes it.
Thats why in the site: http://www.velocity-of-sound.com/vel...ity_stacks.htm you see all of the stacks straight. The wave travels the length of the tube and when it hits the parabolic opening it will reflect back into the tube. This rearward reflection is the action that compresses the air. The reason why the specific length is tuned for a specific power band is due to the speed in which the wave reflects back down the length of the tube. They are actualy their most efficient at there tuned RPM Region because the pressurazation is in sync with the intake stroke.
Ram air is only efficient and effecticve when air is being pushed into the intake at a rate faster than the engine consumes it.
Originally Posted by bilinghm
Yet another example:
As the valves open and close, letting in charges of air, resonances are created. Many things create resonances, such as the valves rapidly opening and closing or the pistons moving back and forth. When an intake valve closes, for example, it sends a wave of compressed air back into the intake, in the reverse direction. This wave of air rebounds inside the intake, and when timed perfectly will return to the valve just as it is again opening. This rebound effect can create as high as a 7psi intake charge just from the inertia of this rebounding air- as high as some superchargers.
This is another form of valve tuning, and it works on the principles of Helmholtz Resonance. A static intake manifold can only be optimized for one specific RPM, so it is beneficial to develop a method to vary the intake length and/or volume. The resin intake manifold that Mazda used to create their 2.3l engine has a valve that changes the volume of the intake runner pipes, changing the resonance frequency of the intake inertial charge. The switchover occurs rather discretely at 4500rpm. Each state is tuned to return a wave of pressure to the intake valve at a different RPM.* These two intake runners are switched at a certain RPM, and create a supercharger-like effect on the intake.* This allows Mazda, combined with the variable intake timing, to get a relatively broad torque band, even if not as broad as some VTEC engines. Harnessing and optimizing engine resonances is a fundamental and essential part of engine design, as it allows efficient transfer of air. The 9000rpm RX-8 actually has a three chamber variable inlet design!* Mazda calls their multi-chambered intake a VIS (Variable Intake System), though they are more generally called a VLIM (Variable Length Intake Manifold).
As the valves open and close, letting in charges of air, resonances are created. Many things create resonances, such as the valves rapidly opening and closing or the pistons moving back and forth. When an intake valve closes, for example, it sends a wave of compressed air back into the intake, in the reverse direction. This wave of air rebounds inside the intake, and when timed perfectly will return to the valve just as it is again opening. This rebound effect can create as high as a 7psi intake charge just from the inertia of this rebounding air- as high as some superchargers.
This is another form of valve tuning, and it works on the principles of Helmholtz Resonance. A static intake manifold can only be optimized for one specific RPM, so it is beneficial to develop a method to vary the intake length and/or volume. The resin intake manifold that Mazda used to create their 2.3l engine has a valve that changes the volume of the intake runner pipes, changing the resonance frequency of the intake inertial charge. The switchover occurs rather discretely at 4500rpm. Each state is tuned to return a wave of pressure to the intake valve at a different RPM.* These two intake runners are switched at a certain RPM, and create a supercharger-like effect on the intake.* This allows Mazda, combined with the variable intake timing, to get a relatively broad torque band, even if not as broad as some VTEC engines. Harnessing and optimizing engine resonances is a fundamental and essential part of engine design, as it allows efficient transfer of air. The 9000rpm RX-8 actually has a three chamber variable inlet design!* Mazda calls their multi-chambered intake a VIS (Variable Intake System), though they are more generally called a VLIM (Variable Length Intake Manifold).
Yes the vast majority of vehicle with individual cylinder intke runners are taking advantage of V-stacking thats why they are designed that way. the wave hits the first major opening and reverses direction just like I was describing, in all the engines you listed its the intake runner that does this not the whole system.
If you want to list the vehicles that do this dont for get any vehicle that has a RB25DE or the ever famous SHO from ford that has the multi length intake runners, the engine was made by yamaha.
RTFQ on the original reason for the thread, you keep gettting hung up on the intake manifold itself. I already know that that takes advantage of resonance to increase power. The question was, "Is that peice a velocity stack" NO it is not.
Originally Posted by HyperSprite
punish-her,
Maybe what you are talking about has nothing to do with automotive applications at all.
For ram charging/pressure wave tuning, there is no requirement that the pipes be straight. As a matter of fact, in the real world, I can't think of any intake systems that don't have at least one bend in them and most have more.
This same tuning technique is also used in exhaust systems and again, not one straight system in the real world but exhaust it beyond the scope of this thread.
Also, on a different note
Nobody as far as I have seen is talking about "Ram Air" and it's not relevant to this thread. Ram charging/pressure wave tuning (or what you call stacking) is an entirely different intake subject.
Chris
Maybe what you are talking about has nothing to do with automotive applications at all.
For ram charging/pressure wave tuning, there is no requirement that the pipes be straight. As a matter of fact, in the real world, I can't think of any intake systems that don't have at least one bend in them and most have more.
This same tuning technique is also used in exhaust systems and again, not one straight system in the real world but exhaust it beyond the scope of this thread.
Also, on a different note
Nobody as far as I have seen is talking about "Ram Air" and it's not relevant to this thread. Ram charging/pressure wave tuning (or what you call stacking) is an entirely different intake subject.
Chris
A) this has every thing to do with auto applications. Physics is physics. Wheather on marine engines, jet engines, or automobile engines its all the same.
B) Ram air does not utilize stacking, said that many times before and lots more in the future.
C) The smooth intake set up was for V-stacking and resonance to create an effective sinus pressure wave, not ram air. Ram air you just shove it in and it will go where it needs to go. The stacking will occure in the intake runners (if designed as such), not the air box. Not gonna get destracted with the principles of ram air.
D) Industry wide people are grabbing on to buzz words and catch phrases, unfortunately Velocity stack is one of those. People are looking at the parabolic curve and saying it must be a v-stack. Not in all cases. Most cases its to aid the transition of air into the intake system.
Last edited by punish_her; Apr 12, 2006 at 04:38 PM.
Originally Posted by punish_her
Making this short
A) this has every thing to do with auto applications. Physics is physics. Wheather on marine engines, jet engines, or automobile engines its all the same.
B) Ram air does not utilize stacking, said that many times before and lots more in the future.
C) The smooth intake set up was for V-stacking and resonance to create an effective sinus pressure wave, not ram air. Ram air you just shove it in and it will go where it needs to go. The stacking will occure in the intake runners (if designed as such), not the air box. Not gonna get destracted with the principles of ram air.
D) Industry wide people are grabbing on to buzz words and catch phrases, unfortunately Velocity stack is one of those. People are looking at the parabolic curve and saying it must be a v-stack. Not in all cases. Most cases its to aid the transition of air into the intake system.
A) this has every thing to do with auto applications. Physics is physics. Wheather on marine engines, jet engines, or automobile engines its all the same.
B) Ram air does not utilize stacking, said that many times before and lots more in the future.
C) The smooth intake set up was for V-stacking and resonance to create an effective sinus pressure wave, not ram air. Ram air you just shove it in and it will go where it needs to go. The stacking will occure in the intake runners (if designed as such), not the air box. Not gonna get destracted with the principles of ram air.
D) Industry wide people are grabbing on to buzz words and catch phrases, unfortunately Velocity stack is one of those. People are looking at the parabolic curve and saying it must be a v-stack. Not in all cases. Most cases its to aid the transition of air into the intake system.
B) and C), your the one that keeps bringing you ram air, you are the only one talking about it. It's never been in the scope of this thread.
D) If manufacturers, distributers and retail shops call a certain item a "widget" and this goes on for years, it's a widget regardless of what the dictionary says.
Really it seems as though you don't bother reading what I have said and just skim it and reply, I am done with that. You can have the last word, anyone who reads this will know what's going on.
Unsubscribing
Chris
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