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Discussion Starter #1
I attempted to remove the VIAS from the air intake but couldn't get it out. There are two torx screws that hold the vacuum lever to the valve and another two torx that hold the valve in place into the manifold.

After removal the valve was a little loose but I couldn't pop it out. If you play with the lever you can feel the flap open and close on the inside of the intake, but it didn't seam that the flap itself was holding it in.

The service manual doesn't go into removal or replacement of the VIAS system.

I was experimenting here because of the VQ35 vias removal mod got me curious. The Variable Intake System adds torque to the bottom end but chokes off the high end. I wanted to see just how much of a difference it makes.

Anyways I did find out that if you disconnect the wires to the VIAS solenoid you will lose A LOT of high end since the valve stays shut the whole time. I'd like to pull the whole VIAS system out and block off the hole in the intake.

Have any of you ever played with this system?
 

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I dont know what kind of topend gains you could see by removing this but i dont recomend it.. I put my truck on the dyno and the losses in tq and hp below 4k were so much i couldent consider this to be a good mod to do ESP on a truck that i tow with..

-Sam

good luck tho.
 

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Discussion Starter #3
how'd you pop yours out? just pryed it? i was afraid of breaking the thing.
 

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I attempted to remove the VIAS from the air intake but couldn't get it out. There are two torx screws that hold the vacuum lever to the valve and another two torx that hold the valve in place into the manifold.

After removal the valve was a little loose but I couldn't pop it out. If you play with the lever you can feel the flap open and close on the inside of the intake, but it didn't seam that the flap itself was holding it in.

The service manual doesn't go into removal or replacement of the VIAS system.

I was experimenting here because of the VQ35 vias removal mod got me curious. The Variable Intake System adds torque to the bottom end but chokes off the high end. I wanted to see just how much of a difference it makes.

Anyways I did find out that if you disconnect the wires to the VIAS solenoid you will lose A LOT of high end since the valve stays shut the whole time. I'd like to pull the whole VIAS system out and block off the hole in the intake.

Have any of you ever played with this system?
Sounds like a great way to lose a whole pile of low end torque. Trust me, you aren't smarter than the factory. Especially not when you're trying to compare this motor to a VQ35. Yes, they are similar... in the same way that our DNA is similar to a chimpanzees.

Removing the VIAS on this truck is about as silly as disconnecting the variable cams.
 

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Discussion Starter #5
Hey, you know there's nothing wrong with wanting to know how these things work. Vehicles come from the factory engineered for a smooth ride. A CAI is a big improvement on performance, but they designed the stock intake to stay quiet. Nissan could have slapped on a nicer (high flow) muffler too, but hey, your average consumer might not like drone in the cabin at highway speeds. It's all give and take. Thanks for your .02 though.
 

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Hey, you know there's nothing wrong with wanting to know how these things work. Vehicles come from the factory engineered for a smooth ride. A CAI is a big improvement on performance, but they designed the stock intake to stay quiet. Nissan could have slapped on a nicer (high flow) muffler too, but hey, your average consumer might not like drone in the cabin at highway speeds. It's all give and take. Thanks for your .02 though.
Sorry, I didn't mean to sound condescending... it's just that people will try all sorts of things to make power and 99% of them don't. Yes, a cold air intake and free-flowing exhaust will help, but removing the VIAS will just simply not help things at all.

Intake manifold runners are tuned to maximize a ram-air type effect that occurs when the intake valves close and the air which was rushing into the engine reverses flow and causes a pressure wave. The length of the runners determines at what RPM this causes air to be crammed into the cylinder by the wave. Variable length runners help to maximize the RPM window where this happens.

Now, for a forced induction application you are already feeding in pressurized air, so you want as simple and straight of a path as possible. Thus, variable runner systems fall out of favor. But especially on a truck where you want low-RPM torque, changing what the factory did is almost assuredly going to result in a loss of low-end power.

The 350Z guys do this because they aren't towing things or requiring low end torque the way a truck does. They are more concerned about flow at high RPMs, and removing the VIAS seems to help them achieve that. But, I can guarantee that a back-to-back dyno run would show a loss of low end power equal to whatever top end power they gain from that modification.

Stick to the tried-and-true mods... hope that explanation helps somewhat!
 

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if you take away the vacuum line and plug, the valve stays open since it opens as vacuum goes to zero. Vacuum closes it. And I totally agree with Sand, I disconnected mine, felt not much on the top and a definite loss down low where most of youre time on the street is spent
 

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Discussion Starter #9
Alright, to resurrect this thread. I was able to remove the VIAS valve. You need to take out the 4 torx screws and just pry it out. Only two actually hold it in but the valve lever gets in the way of taking the back screw out. At first I was afraid of breaking something just prying it out, but with minor force it will pop out.

It looks like a throttle body butterfly, but is made of beefy plastic. My idea here was to block it off so the entire valve was out of the way, creating better air flow than just an open valve.

A simple block plate for this will not work. There is not enough edge (or screws) on the exterior to get a good gasket seal. The vacuum feed line for the valve tank gets in the way. I thought I had a good test setup, but the vacuum ripped my gasket out from behind the cover I made and tried to swallow it.

The original valve seals like a plug, not around the rim. It has an o-ring (well oval) that seals inside the chamber.

So, I would have to get a part made to even test what difference this mod would make. I was hoping to get some quick results for curiosity's sake.

My next option is to try to find a valve from a junk yard and cut the entire valve out of it, support and all. I wouldn't mind having a whole spare upper intake manifold.

Any of you supercharged guys want to sell yours cheap? :)
 

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I'm curious to see how this project turns out.
 

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