This thread is for information only. To help show some that might not know more about there stock Air box. I like the air box but am always open to finding one more piece that will help make performance. This is more to show some of the features of the air box and not an endorsement for one or the other. Because I don’t have an open element on my car I can only use the referenced from what I have seen and experienced
So along with all the drama with intakes and Air boxes. I thought I would shed some light on the air box and what it looks like if you have the Flapper.
The flapper appears to come form the 2005+ model. Some small group of 04’s have them.
The flapper is a extra hole on the bottom of the air box that opens at higher RPM to allow in more air. This shows that piece and the system that goes with it.
As a side note to this. Although the 04’s didn’t come with the Flapper they have the Vacuum power system already in place. This is Odd cause where there is a Vac line on the 05’s there is the same place and parts on a 04. Its just caped off. Almost like they knew in 04 they were going to do this but waited till they were out of the other Air boxes before they switched over. Audi common will put in parts and run .5 model years to install the upgraded parts
So lets look at what you are or are not missing in your air box
First All the B6/7’s should have this. Its behind your front fog light or trim cover. It is a shroud that directs the air to the Aux rad and in this case helps direct air twords the scoop
http://farm4.static.flickr.com/3339/3448959941_6ff71bd5d8.jpg
This next one shows how the shroud goes right into the Aux Rad and the scoop up top
http://farm4.static.flickr.com/3624/3448959985_8af3898ae6.jpg
Now we see the scoop for the air to feed the tube to the air box. Its in the top of the Pic you will see I pushed it out form the actual position to expose it. Normally it is at the point where the shroud come to a point as to access LOTS of the air from the shroud
http://farm4.static.flickr.com/3550/3449774598_db3b3dab53.jpg
This pic is a little harder to see what is going on cause I didn’t expose the top fully. But you will see the back side of the Aux Rad and then you will see the open face of the tube coming form the scoop to the air box
http://farm4.static.flickr.com/3321/3449774670_cfd0de3bbe.jpg
This next pix is the bottom of the air box and the opening for the air delivery system we showed the pics of. If you have a 04 then you probably don’t have this. If you have a 05+ and you pull it out you might see there is a small flap inside the opening. This flap has been removed
http://farm4.static.flickr.com/3646/3449778772_eb5c541d58.jpg
Now for the Last pic. This dose not have anything to do with the flapper or that part of the air system. It dose still have to do with the air box. You will see a part in the air box called a Bell mouth. THIS IS A VERY important piece. This bell mouth helps align the air flow for proper air flow into and past the MAF. This is something missing from most open element intakes.
http://farm4.static.flickr.com/3550/3449783672_7122698cde.jpg
My 02.
The stock air box has a good amount of air going to it already. The flapper mod helped me see even more air past the MAF then before. So for me Im looking into making a better RAM set up using some of the already in place parts from the Flapper system.
For me with the fact that the RS4 uses the same filter as us is a good sign that we should be good with the stock air box. Although there are lots of ideas out there. The bell mouth and the already in place air systems the stock air box look like that is a good platform already. Im just going to see how modding the air box further will possibly help performance.
The 04’s didn’t seem to come with the extra flapper option. When you pulled out the filter you should have seen this in the bottom of the air box. Or you can just look to see if you have a tube connecting to the bottom of your air box.
http://www.audizine.com/gallery/data/500/air_box_mod.JPG
In the end the flapper is just One more source of air. The flapper with the flapper mod did increase the MAF readings thus showing more air was available