3.3TT Have run a couple of test on the OEM air box set up

[dddd]

I've been going through the intake (air box) threads trying to find the information I'm after but with no luck, so I started running some test myself and found that with a completely stock standard car I was getting just on 9 inches of vacuum in the standard air box which is not too bad but far from great, IE there clearly is performance to be gained from getting the standard air box to flow better

The next test was to (un bolt) remove the little straight snorkel piece connecting the air box to the front wall thereby letting the air box suck air from just the inlet of the box only, this resulted in the vacuum level dropping down to just under 1 inch which is really very good, and telling me that the restriction to the standard air box is upstream from that point and that the standard opening is big enough ie no need to cut additional holes in the air box (good)

From what I can see there are two main culprits

1 The convoluted snorkel that simply bolts to the front of the wall, (which should be a simple matter of unbolting)

2 Moulded into the tubing that goes through the wall (that the above snorkel bolts too) is a x-shaped piece looking not unlike a cross brace this piece is fairly big and represents approximately a restriction of 20 to 25% of the surface area of this tube, my question is has anyone removed this (would not be hard to cut out) and can anyone see a possible benefit to this piece

And before anyone asked, no I just don't want to bolt on a Pod style filter, I really am a big believer in having a proper cold air box setup

 

[lamborstingi]

Don’t the velossatech snorkels accomplish what you are after?

 

[lamborstingi]

Just out of curiosity, how did you test this?

 

[dddd]

Don’t the velossatech snorkels accomplish what you are after?

It accomplishes the removal of the snorkel but does not answer the question about the X piece

 

[dddd]

Double post

 

[dddd]

Just out of curiosity, how did you test this?

A mano metre gauge in other words a highly sensitive vacuum gauge plumbed into the drain outlet of the bottom of the air box

 

[Stiletto]

I wonder if the X has any value to break up turbulence. Although, before the filter, it seems to make little sense.

 

[dddd]

I wonder if the X has any value to break up turbulence. Although, before the filter, it seems to make little sense.

It's actually just after the sharp 90 degree elbow, I wonder whether it might have something to do with straightening out the airflow, I don't believe it's as restrictive as I first thought because it's placed at an extreme angle (inside the tube), in other words it's entire surface area never impedes the flow at any one point

I have decided to leave it for now and just put a small funnel shaped device on the tube that is left protruding from the wall after the snorkel has been removed

 

[Hyperjetta]

It's actually just after the sharp 90 degree elbow, I wonder whether it might have something to do with straightening out the airflow, I don't believe it's as restrictive as I first thought because it's placed at an extreme angle (inside the tube), in other words it's entire surface area never impedes the flow at any one point

I have decided to leave it for now and just put a small funnel shaped device on the tube that is left protruding from the wall after the snorkel has been removed

Awesome work! I was also working on a setup to be able to test this very thing but got sidetracked with other projects. Did you use a homemade manometer or is this a special device you got from somewhere? I was planning on using an arduino with a pressure differential sensor and a pitot tube.

I made some air ducts for exactly this purpose and my goal is to get some data to backup their impact. I also cut into the radiator baffle to open up a direct path to beautiful outside air. My thought is that in this scenario there would actually be a negative vacuum reading, meaning positive pressure, leading into the air box to help overcome the restriction of the air filters.

 

[dddd]

Awesome work! I was also working on a setup to be able to test this very thing but got sidetracked with other projects. Did you use a homemade manometer or is this a special device you got from somewhere? I was planning on using an arduino with a pressure differential sensor and a pitot tube.

I made some air ducts for exactly this purpose and my goal is to get some data to backup their impact. I also cut into the radiator baffle to open up a direct path to beautiful outside air. My thought is that in this scenario there would actually be a negative vacuum reading, meaning positive pressure, leading into the air box to help overcome the restriction of the air filters.

View attachment 38552
View attachment 38551

I used a simple homemade unit, it is nothing more then a small bottle of water (mixed with a die to make it clearly visible), a clear tube coming out of it attached to a ruler of some sort
I've used this simple method of extracting air box efficiency over many years and on many different vehicles to I enable me to make the necessary modifications to bring the vacuum levels down as low as possible
I have no doubt what you are proposing will certainly help at high speeds.

 

[dddd]

I can confirm that after removing the front 90 degree snorkel, the vacuum drops from 9 inches down to approximately 4 inches (which is pretty good), considering how easy this is to do (and that you still get 100% cold air), you also have extremely good protection against the rain, I can see no downside to this simple little undetectable mod
No doubt the big mouth additions can only help (at high speeds) with this is well

 

[oddball]

Are you converting to inHg or is that inches of water?
9"Hg vacuum is a lot.....

 

[JVsGT]

I've been going through the intake (air box) threads trying to find the information I'm after but with no luck, so I started running some test myself and found that with a completely stock standard car I was getting just on 9 inches of vacuum in the standard air box which is not too bad but far from great, IE there clearly is performance to be gained from getting the standard air box to flow better

The next test was to (un bolt) remove the little straight snorkel piece connecting the air box to the front wall thereby letting the air box suck air from just the inlet of the box only, this resulted in the vacuum level dropping down to just under 1 inch which is really very good, and telling me that the restriction to the standard air box is upstream from that point and that the standard opening is big enough ie no need to cut additional holes in the air box (good)

From what I can see there are two main culprits

1 The convoluted snorkel that simply bolts to the front of the wall, (which should be a simple matter of unbolting)

2 Moulded into the tubing that goes through the wall (that the above snorkel bolts too) is a x-shaped piece looking not unlike a cross brace this piece is fairly big and represents approximately a restriction of 20 to 25% of the surface area of this tube, my question is has anyone removed this (would not be hard to cut out) and can anyone see a possible benefit to this piece

And before anyone asked, no I just don't want to bolt on a Pod style filter, I really am a big believer in having a proper cold air box setup

Pictures of what you are talking about would be great.

 

[dddd]

Are you converting to inHg or is that inches of water?
9"Hg vacuum is a lot.....

Water, you needed it to react to very small amounts of vacuum, and react fast, water is the best for this purpose

 

[dddd]

Pictures of what you are talking about would be great.

This is just a simple unit I knocked up the other day, as my good one got thrown out sometime ago (don't ask), but the principle is exactly the same. Don't forget to put a couple of air holes in the top of the cap.

 

[JVsGT]

This is just a simple unit I knocked up the other day, as my good one got thrown out sometime ago (don't ask), but the principle is exactly the same. Don't forget to put a couple of air holes in the top of the cap.

I was actually referring to pics of the obstructive parts of the OEM airbox and steps to eliminate them.

 

[dddd]

You're removing this piece, it's well documented, follow the big mouth installation procedures to get access to it

 

[Slip_Angle]

I can confirm that after removing the front 90 degree snorkel, the vacuum drops from 9 inches down to approximately 4 inches (which is pretty good), considering how easy this is to do (and that you still get 100% cold air), you also have extremely good protection against the rain, I can see no downside to this simple little undetectable mod
No doubt the big mouth additions can only help (at high speeds) with this is well

This is really interesting. So removal of this part results in a reduction in pressure thus allowing MORE air to freely enter the intake system, gaining power? It's well documented that the engine/ecu will need time to react to the change. I wonder how much of a difference in power and/or drive-ability we are talking about...

 

[Luc343]

I can confirm that after removing the front 90 degree snorkel, the vacuum drops from 9 inches down to approximately 4 inches (which is pretty good), considering how easy this is to do (and that you still get 100% cold air), you also have extremely good protection against the rain, I can see no downside to this simple little undetectable mod
No doubt the big mouth additions can only help (at high speeds) with this is well

Post some pictures, so we can better see what you have done.