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DIY : Air Box Mods for B6

G-Ride

Imola A4 Quattro 1.8T
COLD AIR INTAKE MODIFICATIONS to Audi B6 2002-2005


Having seen Wally’s write-up and other guys modding the B5 air box, I thought I look a little further into what us B6 guys could do to get a little more cold air into the system. I’ve had a Carbonio in the past and eventually took it back out after what I felt was a lack of performance; most people tend to agree the stock air box is the way to go. Hence why I’ve been reading and exploring different options for the B6.

There’s only one real reason you’d bother doing this kind of thing. More Air + More Fuel = More power....simple science.

On completion of the mod, I found only slightly more induction noise that is barely noticeable. You certainly won’t be getting any attention from the establishment from this mod. The car pulls nicely, turbo spools quite quickly and comes on early.

A little poking around the engine bay, I found there is actually a factory cut-out in the chassis for what I can only assume was for a Vent, S4 Air box maybe? What made it even easier to get a secondary inlet to the air box was the out-line that is etched/cast in the plastic of the air box so naturally it all fell into place quite easily.

It’ll probably set you back about 3-6 hours depending on how comfortable you are pulling bits and pieces out of your car. It’s not exactly rocket science, you’ll find the concept and plan pretty straight forward after you see all the components, holes etc.

Additionally, to finish off the Mod, I suggest purchasing an intake snorkel from a V6 model. This was recommended to me a while ago by James our guru @ Audvolks.
It’ll cost you about $50-60 and removes the restriction in our intake’s which are about half the size. It is a really tight fit! You’ll likely spend the first half an hour swearing and wondering ‘how the f#$% am I supposed to fit this thing in here?!?’ It takes a little work but it fits...

The part number for the V6 snorkel is (8EO 129 618L).

Heres a comparison, you can see just how much wider it is.

intakesnorkles.jpg


MAKE SURE YOU DO THIS WHILE THE ENGINE IS COLD!!
You’re hands will be coming in close proximity to the exhaust manifold and turbo which can get extremely hot. You cannot do this with a warm/hot engine.

Tools required

1 x Short screw driver set or socket screwdriver bits
1 x Set of Torxx Bits
1 x Socket Set
1 x Dremel or I guess you could use a drill and hacksaw blade.
1 x 100-130 Grit Sand/Emery Paper
1 x Car Jack and Stand
6 x Stubbies of your favourite beer.


Materials required (all available at Bunnings etc.)


1 x V6 Intake Snorkel (Optional 8E0 129 818L)
100x 200mm Brass Pressed Vent (I used ‘Haron’ Brand)
1 x Can of Matt Black spray paint, something like Kill Rust for weather endurance
1 x Tube of Aqua Kneed-It
1 x 20cm x 20cm of fly screen, I chose a metal mesh rather than plastic.
1 x 1m metre of foam rubber.
1 x Pack of Bolts/Nuts/Washers (find something suitable to fit the vent)


All this will cost you around $50.00

Step 1 – Air box Removal.


You’ll need to start by removing your air box. Firstly unscrew the two Phillips head screws that hold the factory intake snorkel and remove the intake snorkel from the front support frame and the top of the air box.

Take a quick look around at the air box and how everything is oriented. There’s the lower half and top half of the air box, MAF is on top (where the turbo intake pipe connects to) Secondary Air Injection (SAI) hose is to the left of that.

You’ll need to disconnect both the SAI hose and the turbo intake pipe (TIP) from the air box. The clip on the SAI just needs to be pinched either side and it’ll come right off with little force. The turbo intake pipe is held on by a hose clamp, loosen it off and disconnect the pipe.

You’ll need to go ahead and disconnect the MAF sensor wire too.

I suggest you take off the aluminium heat shield on the right of the air box next to the turbo. There’s not much room to get a screw driver in there so I suggest using a ratchet with a screw driver bit attached. Make sure it’s magnetic or you’ll be pissed when you drop it down into the engine bay, been there done that....

Once it’s off, you’ll see a hard vacuum line that runs across the top of the air box and down the side behind the heat shield. Unscrew the screws so the hard pipe assembly can be easily moved around. The MAF/N75 wiring is also clipped to the top of the air box just to the right of the factory inlet; you’ll need to gently pull that up so it’s free to move around.

At this point you’re ready to remove the air box... Up the top of the air box there’s a plastic lug that holds the air box to the side of the engine bay/chassis, you need to pop that out with a flat head screw driver. You should be able to wiggle the air-box off the chassis and lift it out. The vacuum lines and MAF/N75 wiring may hamper your attempts to remove the air box, but just move everything aside gently. It’s a bit tricky the first time.

Alright, have a look around, you’ll see behind where the air box sat there’s a little vent cut out in the chassis... This is what we want to open up on the air box and fender liner to get some more air-flow into the air box. Take a look at the air box itself you can see the outline of that vent etched/cast into the side.


Here's a picture of the vent you're going to be using to draw air into your airbox.

chassisvent.jpg





Step 2 – Air box Modification.

Ok, you’ve got the air box out; unscrew the top section from the lower section. There are only two Phillips head screws to undo then separate them.
Take out the filter. You don’t need to do anything to the filter or top half of the air box in this DIY, it’s just the lower that concerns us so put the top half somewhere safe.

Heres a picture of the position and outline of vent you'll need to cut from the lower portion of the airbox.

insideairboxcutout.jpg
insideairboxcutout2.jpg


You’ll need to get that dremel hooked up with a cut off disk. You can see the outline in the picture of what you need to cut. I suggest set the dremel speed to something moderate so you’ve got more control and it doesn’t just run off on you. With a steady hand, start to cut along the lines you see in the casting. I suggest cutting inside of the lines so it gives you space to grind the rest out with a sanding wheel. Always better to cut less and grind what you missed. Once you get it just right, clean it up with some fine grit sandpaper etc.

Once this is done, you’ll need to grab the air box and turn it upside down. Around the edge of your hole, grab some sandpaper and rough up the edges and about 1cm around. This will give you a good bonding surface for the Aqua Kneed-It.
Grab your flyscreen mesh and line it up over the hole, grab a pair of scissors and cut it to shape. You really don’t end up needing much of it.

Next step is to bond the mesh to the air box. Grab out the aqua kneed-it and cut yourself a disc to work with. I think the packet says you’ve got about 12 minutes to work with it. After an hour it’s cured, you can machine it, drill it, and sand it....glorious.

It’s a polymer that needs to be worked and cures from air. So mix it around in your fingers, it’ll start getting softer when it does put a thin amount around the outside of your hole and work it in. Once you’ve got that all the way around the hole, line your mesh up and press it in, pull it tight etc make it look nice. I got another bit of Aqua Kneed-It and layer it over the top of the mesh around the edges it doesn’t look the best but you can sand it down after a few hours and it looks fine. You can always paint it too!

You’ll have to let that set for a few hours. I just left it over night and came back the next day. Once it’s set, clean it up a bit, sand it back and paint it if you want it black.

When you're done, it should end up looking something like this..this picture was taken during a test fit..

intake1.jpg


If you're happy with the result and fitment, you can go ahead and put your airbox back together again and start going about re-installing it.

When you have it all back, I took some of the foam wadding and packed it in around the vent so that it forms a really good seal between the airbox and the chassis vent. This is only one peice in place in the picture below theres more now i just don't have pictures of it. There wasnt any need to use anything adhesive as the pressure of the airbox against the chassis keeps it well in place.
foamwadding.jpg


Your about half way done now. Once you have everything in the engine bay re-assembled, its time do get the vent sorted in the fender liner.

With a bit of luck you've done the prep work by spray painting the brass vent black and allowed it enough time to dry.

You'll need to jack the car up off the ground on the drivers side (aus) and support it on a stand so you can remove the wheel. This will give you plenty of access to get the fender liner out. This part is pretty straight forward there are about 9-10 torxx screws that hold the liner in place. Remove them all and you'll be able to slide the liner out.

I suggest you hold the liner in place and look at where you need to position the brass vent to line up with the cut out in the chassis.

Here are some pics so you can take a look at the area without the liner on.

wheelarchvent.jpg
vent2.jpg


Marking out the vent position wasn't too hard, you need to use a little bit of initiative here and figure out how you need to place it. Thankfully the brass vent bends really easily so you can put it up against the liner with a lead pencil and mark the outline. Once you mark out the outline, mark about a 10mm square into each corner so you have enough room for the bolt positions to be drilled and fitted. Mark another rectangle about 1cm inside the original outline....less is more.

I really cant stress enough to cut less of an area than you really need, this way you can grind the rest of the area out if you need more for a snug fit. Last thing you want is to have is a hole thats bigger than the vent..You'll be trying to find another vent or fabricating something else.. Just plan it well before you cut. Keep testing until you are happy with the fit then hold the vent in place and mark the bolt holes with a led pencil so you can drill them out. Drill them out and then do some test fitting against the liner. Just bend the vent so it fits perfectly, you'll get the idea. Once you've got it fit correctly, put the bolts washers and nuts in and tighen her up.. I didn't bother with mesh behind the vent as theres mesh on the airbox and the filter after that. If I find it gets too dirty i'll put more mesh behind the grill.

I had extremely long thin bolts so I ended up cutting off the excess with the dremel when I was done, there was a good 3cm of thread hanging out the other side.

When you're done you should end up with something like this..
vent.jpg
ventpos2-1.jpg


Not to bad eh? All you need to do now is screw the liner back in, put the wheel back on and enjoy!

:_b:
 
Last edited:
well done! looks like we all have been busy this weekend.

Thanks mate, I think it actually does make a difference. The car was pulling a lot more smoothly on the way to work this morning, power is nice and punchy when you want it. I should have taken some logs of before and after. I might try and get another airbox lower section and do some spreadsheets and post them up here.
 
Thanks mate, I think it actually does make a difference. The car was pulling a lot more smoothly on the way to work this morning, power is nice and punchy when you want it. I should have taken some logs of before and after. I might try and get another airbox lower section and do some spreadsheets and post them up here.
i noticed the same thing this morning. car was less "jolty" and car seems to struggle less and gear changes are more forgiving at lower rpms- especially handy in peak hour..i put it down to the cooler ambient temp, see how it stacks up after the rubber seal gets put in and temp rises...on the up side i have another spare vent , so im going to put in another IC exhaust vent on the opposite side.
 
i noticed the same thing this morning. car was less "jolty" and car seems to struggle less and gear changes are more forgiving at lower rpms- especially handy in peak hour..i put it down to the cooler ambient temp, see how it stacks up after the rubber seal gets put in and temp rises...on the up side i have another spare vent , so im going to put in another IC exhaust vent on the opposite side.

The gear changes were something that definately caught my attention.
I was considering venting the other wheel liner too, just to get some of that hot air out of the engine bay...Couldnt hurt. I dremeled out the drivers side fog light cover to get air flow around the turbo area to try and remove some of the heat. The cover looks like a vent, but the back of the vents is actually just sealed over so normally no flow gets through. I think the 'fresh air' fog cover is used on the S-lines with the twin coolers and doesnt come with the standard a4. Car's definately feeling stronger.
 
The gear changes were something that definately caught my attention.
I was considering venting the other wheel liner too, just to get some of that hot air out of the engine bay...Couldnt hurt. I dremeled out the drivers side fog light cover to get air flow around the turbo area to try and remove some of the heat. The cover looks like a vent, but the back of the vents is actually just sealed over so normally no flow gets through. I think the 'fresh air' fog cover is used on the S-lines with the twin coolers and doesnt come with the standard a4. Car's definately feeling stronger.

yeah i did that as well, love my dremel, i figured Audis are manufactured to colder European climates and not 45 degree days we are used to. so im cutting the crap out of every plastic guard i can find, whilst maintaining a stock look hence the vents, on first glance to someone not used to our cars it could be mistaken as stock.
 
Stay tuned...S4 Airbox mods to come.
S4 lower section mates with the A4 uppersection. (3 intakes).
 
Another take on this mod: old thread with pretty pictures

Since then, I've actually added a flexi-duct from the front (lower driver side grille) up into the guard side inlet. Personally, I wouldn't draw air from the wheel well - there's lots of muck thrown around and there is too much turbulence for any positive pressure.
 
Another take on this mod: old thread with pretty pictures

Since then, I've actually added a flexi-duct from the front (lower driver side grille) up into the guard side inlet. Personally, I wouldn't draw air from the wheel well - there's lots of muck thrown around and there is too much turbulence for any positive pressure.

Nice Ratty, I had no idea you'd already done this. Seem's we've been re-inventing the wheel.

Supprisingly there is minimal garbage that gets past the vent in the wheel liner. Quite a few VAG cars's actually have vented fender liners from the factory.

I certainly saw some small gains in doing this.
 
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