ViCS vs VTCS with PICS!

[StealthWyvern]

I think this might help with some of the cofonusion... i know I have been getting this all mixed up lately.

No cold start up issues. You must leave the 2 VTCS/VICS solenoids plugged in, but remove the actuators and all the vacuum lines to the solenoids. You must also remove the green/white check valve in middle of the manifold and put a straight piece of vacuum line there, be sure you use high grade silicone line and reuse the clamps, replace all the gaskets for a leak free seal and torque to specs.

Posted by JDM Sam in this thread..
http://www.mazdas247.com/forum/showpost.php?p=4611840&postcount=1

"The VTCS is a emissions system to increase turbulence to improve start up emissions. Other cars have similar systems. VTCS is more of a restriction compared to the VICS."

 

[Wagonbacker9]

VICS, i believe, is designed to change the port volume which aids in production of low end torque.

 

[BOOSTR]

from the man's protegefaq.net

"What is VICS?
VICS is "Variable Inertia Charging System" and is also refered to as "Variable Intake
Control System". In conventional intake manifolds, they are designed to have an air flow
compromise between low end and top end power. Because of this compromise, power
delivery from the engine is not optimum nor ideal. What some manufacturers (such as
Nissan and Mazda for example) have done is designed the intake manifold to have an
isolated runner system (there are many types of intake manifolds) to offer the best flow
characteristics. They didn't stop there. To squeeze as much power out of the engine, yet
allowing the vehicle to be streetable and mass producable, they added a secondary set
of intake runners into the manifold. With this dual runner system, there is the long runner
system for low to mid level RPM operation, and the short runner system for high RPMs.
On Mazda's dual runner intake systems (hereafter refered to as "VICS"), they designed
the long runners to be narrow and oval in shape to help promote air velocity at the lower
RPM ranges. As for the short runners, they are much larger and circular in shape to allow
for maximum flow capability at high RPM. There are butterfly shutter valves fitted over
the short runner and they are normally closed off. When engine speed is reached to a
predetermined rate by the ECU, a solenoid valve is opened and vacuum opens the
butterflies to allow for additional air flow into the engine. Hence the reason why the
system is "variable". It allows for optimum drivabilty and performance at most RPM
ranges. Note when this system is used with high boost forced induction systems, they
hinder performance rather than aid it because of the runner sizes. For high boost
applications, it is recommended that a large single (stage) isolated runner intake manifold
be used.


What is VTCS?
VTCS is "Variable Tumble Control System" or commonly refered to as swirl control
valves. This system only exists on the 3rd generation ULEV certified cars and is used
only on engine cold starts (under the following criteria: coolant temperature is less than
65C/149F). When active, the butterflies located at the end of the intake runners are
closed leaving a small notch aproximately 1/4 the size of the runners to allow for
turbulent air flow to reach the head and combustion chamber. The swirl caused by the
turbulent air aids the combustion process when the engine is still in its cold state "rich
fuel mixture" condition, therefore reducing cold start emissions. Hydrocarbon emissions
are significantly reduced due to this system. This system is also the cause of the infamous
cold start engine rattle that seem to happen between 2500-2800rpm on some 2.0l
engines. There is no known legal fix to this issue yet and Mazda is aware of the problem.
What is happening on the few 2.0l engines is normal and there is no need to worry. The
inclusion of this system also causes some performance restriction to the engine even when
the system is inactive."

 

[stevew145]

from the man's protegefaq.net

"What is VICS?
VICS is "Variable Inertia Charging System" and is also refered to as "Variable Intake
Control System". In conventional intake manifolds, they are designed to have an air flow
compromise between low end and top end power. Because of this compromise, power
delivery from the engine is not optimum nor ideal. What some manufacturers (such as
Nissan and Mazda for example) have done is designed the intake manifold to have an
isolated runner system (there are many types of intake manifolds) to offer the best flow
characteristics. They didn't stop there. To squeeze as much power out of the engine, yet
allowing the vehicle to be streetable and mass producable, they added a secondary set
of intake runners into the manifold. With this dual runner system, there is the long runner
system for low to mid level RPM operation, and the short runner system for high RPMs.
On Mazda's dual runner intake systems (hereafter refered to as "VICS"), they designed
the long runners to be narrow and oval in shape to help promote air velocity at the lower
RPM ranges. As for the short runners, they are much larger and circular in shape to allow
for maximum flow capability at high RPM. There are butterfly shutter valves fitted over
the short runner and they are normally closed off. When engine speed is reached to a
predetermined rate by the ECU, a solenoid valve is opened and vacuum opens the
butterflies to allow for additional air flow into the engine. Hence the reason why the
system is "variable". It allows for optimum drivabilty and performance at most RPM
ranges. Note when this system is used with high boost forced induction systems, they
hinder performance rather than aid it because of the runner sizes. For high boost
applications, it is recommended that a large single (stage) isolated runner intake manifold
be used.


What is VTCS?
VTCS is "Variable Tumble Control System" or commonly refered to as swirl control
valves. This system only exists on the 3rd generation ULEV certified cars and is used
only on engine cold starts (under the following criteria: coolant temperature is less than
65C/149F). When active, the butterflies located at the end of the intake runners are
closed leaving a small notch aproximately 1/4 the size of the runners to allow for
turbulent air flow to reach the head and combustion chamber. The swirl caused by the
turbulent air aids the combustion process when the engine is still in its cold state "rich
fuel mixture" condition, therefore reducing cold start emissions. Hydrocarbon emissions
are significantly reduced due to this system. This system is also the cause of the infamous
cold start engine rattle that seem to happen between 2500-2800rpm on some 2.0l
engines. There is no known legal fix to this issue yet and Mazda is aware of the problem.
What is happening on the few 2.0l engines is normal and there is no need to worry. The
inclusion of this system also causes some performance restriction to the engine even when
the system is inactive."

To put it in basic terms,
VICS (larger circular ports) opens at a higher rpm (probably around 4500 rpm) to increase the volume of air going through the intake manifold. It basically makes the runners extra large, to maximize the air flow. Closed when the car is below 4500 rpm to somewhat restrict air flow giving good bottom end torque. Something you shouldn't tamper with, because it is finely tuned for a good mix.

VTCS (smaller oddly shaped ports) are valves that are only closed on cold starts to increase air turbulence to maximize air fuel mixing in the combustion chamber to decrease emissions. You can get rid of this completely and get a decent gain in air-flow volume into the engine, but you will lose some of the turbulence and get a poorer mixture, which could lead to incomplete combustion. Especially during cold starts.

 

[Alamo1]

Now... JDM Sam says that both should be removed on a turbo car so that you have higher flow capabilities all the time. i have the milling machine that I could do it with and wonder wether it is worth the labor to hog all of that material out.

What do you guys think?

 

[mattxhand]

Okay, so my MSP feels REALLY restricted until about 4500-5000 RPMs. Could it be one of these?

 

[Tom03es]

To put it in basic terms,
VICS (larger circular ports) opens at a higher rpm (probably around 4500 rpm) to increase the volume of air going through the intake manifold. It basically makes the runners extra large, to maximize the air flow. Closed when the car is below 4500 rpm to somewhat restrict air flow giving good bottom end torque. Something you shouldn't tamper with, because it is finely tuned for a good mix.

This is somewhat misleading. When the VICS valves open, they aren't making the runners any larger. They are, however, opening up a resonance chamber which uses the sound waves coming back out of the intake manifold and redirects them to help "cram" the incoming air into the combustion chamber better. No appreccable amount of air flows through the VICS butterfly valves. It's all sound (pressure) waves that are tuned.

 

[slavrenz]

This is somewhat misleading. When the VICS valves open, they aren't making the runners any larger. They are, however, opening up a resonance chamber which uses the sound waves coming back out of the intake manifold and redirects them to help "cram" the incoming air into the combustion chamber better. No appreccable amount of air flows through the VICS butterfly valves. It's all sound (pressure) waves that are tuned.

Um... I don't think so. How could there be no appreciable air going through those VICS butterflies when you've essentially just doubled the flow of your airflow to the engine?

I agree that those triangles cut in the front work as resonance chambers. But the butterflies themselves serve to let more air flow through them and thus keep the engine from starving at WOT.

 

[Tom03es]

Um... I don't think so. How could there be no appreciable air going through those VICS butterflies when you've essentially just doubled the flow of your airflow to the engine?

Because there is no inlet attached to the VICS chamber. The air in that chamber is basically stagnant. That's how there is no appreciable airflow going through the VICS butterflies. It's all about sound waves to help "cram" more air into the cylinders.

 

[Signature Sound]

Hell YES! HOG THE PISS OUTTA THAT THING!! I spent over 40 hours porting, polishing and measuring. It was worth every second. Think about what size intake and exhaust you will be running to achieve the HP levels you are shooting for. Then research the port size to match for optimal flow and match it with the exhaust side. Spool, response and top end will be noticeably improved.

Now... JDM Sam says that both should be removed on a turbo car so that you have higher flow capabilities all the time. i have the milling machine that I could do it with and wonder wether it is worth the labor to hog all of that material out.

What do you guys think?

 

[Joost27]

I find it weird that the 1.8l manifolds have VICS, but not VTCS. I like it since there is minimal restriction, but just find it weird since the 2.0l and 1.8l heads are the same and what not.

 

[stevew145]

This is somewhat misleading. When the VICS valves open, they aren't making the runners any larger. They are, however, opening up a resonance chamber which uses the sound waves coming back out of the intake manifold and redirects them to help "cram" the incoming air into the combustion chamber better. No appreccable amount of air flows through the VICS butterfly valves. It's all sound (pressure) waves that are tuned.

It does increase the amount of airflow. The plenum is cut in half by the piece of metal where the butterflies/ports are, when the butterflies are closed you are only getting flow through the smaller ports, increasing velocity, when the butterflies are open, you are getting a massive increase in flow just because the opening has more than doubled. It doesn't make the runners larger, but increases flow through the manifold. It doesn't open up any other chambers or runners, just lets more air flow through the manifold.

 

[Wagonbacker9]

the VICS valve doesn't increase flow, it increases the intake port volume. its the VTCS that increases flow volume.

 

[stevew145]

Having vics closed is like each cylinder is breathing through a long, thin straw, having it open is like having each cylinder breathing through that same straw + a larger, shorter straw. There are many benefits from this. Vtcs only reduces flow on cold starts, and is just in the way when not in use.

 

[Wagonbacker9]

i believe you have VICS and VCTS confused.

 

[stevew145]

Look here

 

[njaremka]

It does increase the amount of airflow. The plenum is cut in half by the piece of metal where the butterflies/ports are, when the butterflies are closed you are only getting flow through the smaller ports, increasing velocity, when the butterflies are open, you are getting a massive increase in flow just because the opening has more than doubled. It doesn't make the runners larger, but increases flow through the manifold. It doesn't open up any other chambers or runners, just lets more air flow through the manifold.

Having vics closed is like each cylinder is breathing through a long, thin straw, having it open is like having each cylinder breathing through that same straw + a larger, shorter straw. There are many benefits from this. Vtcs only reduces flow on cold starts, and is just in the way when not in use.

Look here

dude, really? you contradict yourself by posting a link that explains the VTCS system, not the VICS system.

the VICS system does NOT open shorter runners, and it pains me to see so much wrong information being spread on the interwebz, but what can you do.

oh, and the protege FAQ is wrong with respect to VICS operation, but edwin is too much of a wanker to admit it and make the change.

 

[Tom03es]

Having vics closed is like each cylinder is breathing through a long, thin straw, having it open is like having each cylinder breathing through that same straw + a larger, shorter straw. There are many benefits from this. Vtcs only reduces flow on cold starts, and is just in the way when not in use.

Have you ever had your manifold out and looked at it? You could fill the cavity that the VICS butterflies closes off with water and it would hold that water (except for any vacuum nipples that might be attached). There is NO flow of air. It's just a sound resonnace chamber that opens that is tuned to use sound pressure waves to help move the air into the combustion chamber better.

Even if VICS did flow air, you are still limited by the size of the throttle body opening and the size of the intake head ports- these don't change.

You're wrong. Admit it (if even privately to yourself) and move on.

 

[njaremka]

if any of you have actually read the service manual, you would see a very detailed diagram of how the VICS and VTCS systems in the manifold are actually laid out.

[/thread]

 

[McBadass]

Living in Colorado where it gets cold for 8 months of the year... should I not mess with this (VTCS)?