03 mazdaspeed protege
August-7th-2007, 11:35 AM
#31
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Location: Rockland, Maryville
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No, but I'll chime in on a technical note regarding that second set of intake runners. There ain't any. Rather, VICS opens up a chamber which alters the resonance frequency of the intake manifold. The altered resonance facilitates induction at higher flow rates. This way the manifold has two tunings, for high and low rpm operation. 
August-7th-2007, 11:39 AM
#32
Tech/How-To/Northeast Mod
Join Date: Feb 2006
Location: Rochester, New York
Posts: 2,517
No, but I'll chime in on a technical note regarding that second set of intake runners. There ain't any. Rather, VICS opens up a chamber which alters the resonance frequency of the intake manifold. The altered resonance facilitates induction at higher flow rates. This way the manifold has two tunings, for high and low rpm operation.
August-7th-2007, 11:42 AM
#33
Tech/How-To/Northeast Mod
Join Date: Feb 2006
Location: Rochester, New York
Posts: 2,517
so says the bible:
Josh, were you thinking of VRIS (i.e. on the Mazda KL v6 and not the Protege?) It deals with butterflys that open and close resonance chambers. I know the FS-ZE has a resonance chamber on it's intake manifold as well but not us FS-DE guys
Originally Posted by www.protegefaq.net
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.
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.
Last edited by _Kansei_; August-7th-2007 at 11:44 AM.
August-7th-2007, 12:22 PM
#34
Registered User
Join Date: Mar 2007
Location: Rockland, Maryville
Posts: 837
Yeah, I have Edwin's FAQs memorized, but I don't think he's right here. I had this same discussion with Nik and he showed me the figure at the top of 01-13b-10. You can clearly see it in the diagram. Also, next time you take your IM out and see the analog of the attached image, illuminate the "second runner" and you'll see.
August-7th-2007, 12:49 PM
#35
Tech/How-To/Northeast Mod
Join Date: Feb 2006
Location: Rochester, New York
Posts: 2,517
It changes the length of the runner that the air travels through, no? I checked that diagram and that's exactly what I see there.
Thanks for the diagram though --it is different from how I thought the system worked. I thought that from the throttle body it went to 8 runners, 4 of which were direct and 4 of which were extended.
That diagram does prove that it's not a whole lot different than VRIS.. no wonder it doesn't make the noise that the variable intake system on my mom's various nissans made. It was like you got a cold air intake all of a sudden at high RPMs.. a VTEC-ish noise but just from the intake
the blast of power I get at 5500rpms is welcome though
Thanks for the diagram though --it is different from how I thought the system worked. I thought that from the throttle body it went to 8 runners, 4 of which were direct and 4 of which were extended.
That diagram does prove that it's not a whole lot different than VRIS.. no wonder it doesn't make the noise that the variable intake system on my mom's various nissans made. It was like you got a cold air intake all of a sudden at high RPMs.. a VTEC-ish noise but just from the intake
the blast of power I get at 5500rpms is welcome though
Last edited by _Kansei_; August-7th-2007 at 12:52 PM.
August-7th-2007, 01:44 PM
#36
I can has autox now?
Join Date: Nov 2004
Location: ASC, GA
Posts: 3,381
I still have this "hezzisle" problem... and the guy i bought it from had it reflashed, could just be my car though...
August-7th-2007, 02:51 PM
#37
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Join Date: Mar 2007
Location: Rockland, Maryville
Posts: 837
Nope, just opens up the airspace behind the butterfly valve. The volume of air in the chamber affects the airflow past it through a resonance condition. The resonance frequency changes with the volume of the chamber. A small volume works well for lower speed flow, larger volume helps higher speed flow.
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