A6 C6 build.

A6 All/ S6 All
#1

Hello everyone,

My name is Samuel and I recently picked up a 2005 A6 C6 RHD here in Japan and while I intended it to only be a family since its my only vehicle right now I could not resist modding it a little. We all know that itch. Anyways I decided to start with something easily accessible…thats right the intake system. While I am a big lover of going all out crazy on building a Cold Air Intake, I decided to take it easy on this one and just modify the stock air box to be better.

Step 1. Remove the stock air box to inspect it on how to make it better.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/746ABA12-0A7A-4840-B3F9-E382E80DA52F.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/8894522C-389D-4C03-B884-A4ABBBC50784.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/0A7C2AF7-0A0D-4FC1-884F-8A72A946581C.jpg

This little thing is used to help quite the intake system…so of course its going bye bye.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/611F5399-AA48-4DFC-9FD8-7E5FF62503F8.jpg

This little flap thats opened by vacuum on the diaphragm will also go bye bye.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/BC47BCDF-8CDF-4D47-A4E9-1218FE8218D0.jpg

This is the stock intake snorkel that sucks air from inside the fender well into the airbox…this will also go bye bye.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/ADF147B6-0B66-4BB6-894D-AD7191B9E4B1.jpg

Step 2. The MAF…While the stock MAF can be left untouched I decided that the little extra plastic bug catcher inside was a little overkill sooooo…yes thats right It got ganked.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/ED28E8DE-B943-4B62-B26A-9DC8E1A1B025.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/B5B56E50-99E8-445C-B30E-5AC813903D08.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/B968B79B-FCCC-419A-BC75-C5216A8A8C41.jpg

Step 3. I noticed that when the stock filter was removed and the MAF was attached to the air box there was just the right amount of space to put a coupler to attach a different cone filter. But there was these little tabs in the way that had to go.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/BDE8C425-06D8-4B37-BA4D-834A2E3B2EE8.jpg

Next I had to do a little cutting and trimming on some things to make the new filter work but before I get to that let me just show you all some interesting information. I used my OBD2 iphone scan tool to find out what the intake air temps are while driving and while sitting in traffic so I can see how much difference the mods make. SO here are some screen shots of the readings.

This first one was about 10min after start up. Now just to give you an idea of the air temp difference the outside air is 25 degrees Celsius so a difference of 13 degrees. Also notice the timing of the engine at that temp and notice the change from the next couple photos.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/FF40EC59-295D-4374-8BFA-DD0643DFAE68.png


http://i228.photobucket.com/albums/ee159/sugerdady20012001/66A68F99-C635-474D-B710-022F50868A69.png


http://i228.photobucket.com/albums/ee159/sugerdady20012001/526AB3A6-88CD-4F20-B0B8-F233BFF1E226.png


http://i228.photobucket.com/albums/ee159/sugerdady20012001/0F5568BC-BF14-4FE5-B806-D1DEE6F0A024.png

Sooooooooooo we can see there is a HUUUUUGE difference in the timing and air temp as the car heats up to running temp after 30min of running. The outside air never changed temp from 25 degrees but the intake air temp went from 38 not long after start up to 68!!! thats 30 degrees and a difference of 30 degrees of timing to 9. The timing was really retarded to keep the engine from detonating because of all that heat. So needless to say I have my work cut out for me. I will be posting up here again tomorrow after I do some heat wrapping and modding to the intake snorkel to get more cool air into the air box.

Step 2.

#2

Do you have the temperature data from before you started making mods? That would give you a much better baseline of info to work with, to track your progress. Based on what I’m seeing here, you might’ve actually made things worse

#3

That flap that opens under vacuum pressure, if I’m not mistaken, is to prevent the intake from sucking in hot engine bay air, unless the “snorkel” isn’t providing enough air by itself. By removing it, now the airbox is sucking in hot engine bay air all the time. No amount of heat wrap is going to fix that. A better idea, IMO, would be to completely seal the flap, and figure out a way to improve the efficiency of the fender snorkel.

#4

Great right up. We all know how great the stock air box is and it looked like you have just helped continue to show that.

With your posted data. Can you help explain each picture and what it corresponds to. If you look at the time stamp in the upper left hand corner it looks like the results actually got worse as time went on. So helping explain what each picture represents mod wise would be helpful. Great work.

#5

Great writeup!

As Justin pointed out, it is a challenge to improve on the stock intake design, on the v8/v10 Audis. Almost everyone who has tried, as ended up with decreased performance.

That doesnt mean it cant be made better for performance applications, though. If you have solid before and after data, you should be able to determine if your changes have helped, or hindered performance.

Interested to see how this turns out

#6

Yes i am aware of the flap hole sucking in hot air so it will be sealed somehow and only air from a new snorkle will be coming in that side from the fender. The pictures of the temp readings are all from driving the car around before doing anymods at all. The first picture is 10min after start up and the rest of the pictures are a progression over the next 30min of driving so you can see that the intake air temps increased dramadically. So my work will be to get more cold air into the box and heat wrap the stock box and piping to keep that cold air cool. My goal is to keep the stock air box from retaining engine bay heat.

#7

OK lol that makes sense. I was thinking gosh this sucks if I have to tell the guy his project didn’t work.

As for the timing that isn’t going to matter. Timing will be different in warm up mode and for the first few min of running the car. Also the load would be hard to duplicate so as a variable it’s not helpful. We do know that cover air means a better intake charge so better timing will be a result regardless of the actual posted timing.

So far looks great. Super good idea I found more cold air feed helped on my car. Acceleration works best when the air box is a high pressure zone. So closing off any non inducted area is a good idea. Looking forward to more of your testing very exciting and we’ll done.

As a reference post one picture for each test of the temp on the dash. It’s a good help for seeing the outside temperature in each test.

#8

Ok so I pulled the air box out which is super easy thanks to Audi for making at least one easy thing on their cars lol.
Next i pulled the inner fender well liner and folded it back out of the way after jacking the car up and removing the right wheel. I also removed the under tray to gain access to the bumper and other bolts. Heres a picture of the stock snorkle on the car. Sorry for the bad photo it was super bright outside.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/466E5216-D1E6-40B4-9C78-113E656431BE.jpg

Next I pulled the snorkle after removing the 2 screws holding it in from the inside of the engine bay, all very easy.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/32512EC8-9012-4849-B809-6141C40118DC.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/86CCC2BD-2413-482B-A23C-97B5EE2799D0.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/8E2C7362-7260-4E60-9CAC-D53132773CC8.jpg

Next I removed the air box flap so that i can ram air into the airbox constantly.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/9E69F865-61A0-47FB-B606-FF4360ED3923.jpg

There was a little bit of a lip that I knew would be a restiction so i used a dremmel and trimmed it up.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/5365D19E-E7FB-46FA-93C4-4EDFD88C3685.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/C8E671D0-F394-42CD-AFB4-0F32B1F10683.jpg

Next I started the task of adding a little foam with adhesive backing to the air box to give a barrier in between the box and the reflective tape I am used. Its inportant to do this otherwise the tape will just transfer all the heat to the box and not work to keep heat out.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/FA2C0EF2-C5C0-4086-A830-3820D311089C.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/C32A2438-B0FB-4BBC-9A92-2FBE8C9BF3C5.jpg

The good thing about having adhesive backing on the foam is that you can form it to the box.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/F65D8676-3E84-4A69-8C5B-94446AB0A435.jpg

Next i started applying the 0.5mm reflective tape to the box to finish the insulation. And here is the box all finished.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/4FCF3CCC-2554-4FC3-B829-1D0F0D2527B9.jpg

And heres the new HKS foam filter to replace the paper crap that the car came with.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/533DA2B8-D09A-42D4-B2D4-28065287B791.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/7E60C906-0AA8-45B9-93F6-65F9E69E7598.jpg

As you can see I used a coupler from the MAF to a 4x2in piece of aluminum intake pipe i had laying around and then another larger coupler from the pipe to the HKS filter. If you have a cone filter thats not a big around as my filter it would be possible to attach it straight to the MAF but I love the foam filters so I did a little extra to make it work. Also in sure you can see that the inner piece of the box where the ram air from under the grill comes into the box was removed so the filter will fit right, as seen in the next pictures.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/B4B320B0-D36B-4FDC-B039-52C6BDE8636C.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/6D73B502-E7CF-4E38-81F1-E37A63E61765.jpg

Next I had to attach the new temporary snorkle until i can make a better replacement.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/1921742F-8EF0-46A2-95E8-EC077E8F1F4A.jpg

If your wondering whats holding in place yes its duck tape. This is all in the testing stages to see if it works then all make a better snorkle to fit.
Next I pulled the right front fog light grill.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/5933040F-697E-4A7B-A87E-62EBCA983292.jpg

Then I noticed that there was 4 points on the back holding the right section on which would be a perfect location for the new ram air snorkle.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/7EBE9F46-309B-426D-A639-11A9411AEC27.jpg

Next I very carefully used a razor to cut the edges of the tabs to allow me to pull the panel off.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/D8F3F77B-EB72-42B5-A3A6-D2291558EE8D.jpg

I was then able to re-install the grill back in place so it was open for the snorkle.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/AF2CD7C8-C063-44C4-B885-9EF220BBC337.jpg

Next I installed the airbox and sealed up the inlet where the snorkle attatched to the box and installed the MAF to Throttle body pipe that I wrapped. You will notice I removed and sealed up the intake resonator that was attatched to the elbow pipe.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/A0A05E27-323A-4D6B-AE1F-64A91A2B9E54.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/C879B3BA-CEF0-42DC-B206-0C74896987F1.jpg


http://i228.photobucket.com/albums/ee159/sugerdady20012001/D53E7F20-A603-4549-9FF7-6FD4D175A6EF.jpg

Everything from the Throttle body out was wrapped.
And finally after 5 hours of work it was complete and back together for testing.
I do appolagize for not having a picture of my dash showing the outisde temp but i promise it was 24 degrees Celcius.
Ok so after letting it run for a while “about 20min” I took her out on the road to see what difference the mods had made. After cruising for about 10min at 50kph the temps were a steady 34-35 degrees celcius. Now being that the outside temp is only 1 degree colder today then when I took my first intake air temp readings I was suprised and happy. Thats 3-4 degrees colder at only 50kph when I saw 38 degrees at 90kph in my first test. Now heres where it really gets interesting. I didnt take it on the highway like the last time but instead on some local back roads so i could open her up a little. And heres my temp readings after 5min of some spirited driving. Now remember the outside air temps are 24 degrees celcius.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/47DEBFF3-96BE-4108-8C4E-7CCF3B817073.png

At about 70kph cruising after getting on it for a couple minutes I was within 3 degrees of the outside air temp when i had only seen 38 degrees at 90kph before the mods which is 13 degrees celcius difference. Now watch what happened when I was giving it a little throttle up a small hill.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/516F6088-E7EC-4C79-95D5-06A8B4A7E5DF.png

Thats right at only moderate driving I was within 2 degrees of the outside air. I am confident that at higher speed and more throttle with more air being sucked into the intake system that the temps would drop to be even with the outside air. I will have to do more solo driving for that since my gf was riding with me at the time I did this testing so I couldnt open her up all the way.

Ok, so we now know that the mods helped to get the temps down alot by getting alot more air into the air box and keeping that air flowing in while driving down the road. So if your a track junkie or back road kind of guy then this mod will be great for you. Keeping everything sealed same as stock while adding a better flowing filter and snorkle made a noticable difference.

Ok…so performance wise here is what I found. Throttle response is almost instant compared to the very sluggish response it had stock. The low end power seems to be better since the engine is not starving for air like it did with the tiny stock snorkle and resticting air filter. It also seemed to have better pull through the mid range while passing people so the only thing left is to test is flat out at full throttle and see how it does up top. I can only assume it will also benefit since it wont be lacking for air.

Oh and before i forget about idling temps heres a picture of my temp when i let it sit for 20min after driving it hard.

http://i228.photobucket.com/albums/ee159/sugerdady20012001/0DA3AF56-52D5-4976-9076-E338BCD7D047.png

The highest It got was 57 degrees celcius which is 11 degrees lower then the previous 68 from my first test. So even in traffic the mod benefits. The big difference can be seem only in person because the intake air temps on the stock system took time to drop down while after the mods were done you could watch the temps drop by about 1 degree per second while accelerating. All in all I am very happy with the results of this and will be working to inprove the snorkle and possibly building a heat shield in between the box and engine to help keep the box from getting heat soaked from track time or spirited driving. Best of all it all can be done cheaply and retain the stock design which I think is always the better route when it comes to german cars. Anyways Ill be back soon with my next mod so If your interested so far stay tuned.

#9

Lots of hard work. If you can block and help push more air by the bottom fog light into the snorkel that will really help. Right now it’s picking up a or but if you block off and put a scoop to it you can wide the surface area for it to gather air. The RS4 guys do something similar to what you did but they notice a big gain when you have a big air scoop leading to the pick up.

It’s great you are seeing what we all have for years. The stock air box works the best. Adding a few modifications to it helps

#10

Yeah ive owned alot of VW and always knew they were designed well so I figured the audi was also since vw owns them. The air box is big enough and has enough air flow once you open up that snorkle.

#11

Yup lots of us have been doing similar mods to the air box for years. The RS4 has the same size filter and close to the same size air box and they are able to get into the 12.1xx range @ 113+mph so I don’t see us having starvation issues.

#12

Yes I think audi does a great job building their cars they just leave a little room for improvement. I want to pick up a used intake manifold to take apart and play with also. Ive seen jhm’s work and tbey didnt do a whole lot but open ut up a little with some porting and smoothing on the inside. But the biggest upgrade next is manifold back exhaust, that will really open up the engine I think and with a tune and some small mods like light weight crank pully and oil cooler ill be in business for some spirited driving in the mountains here. I just hope i can make jhm’s S4 oil cooler work on my engine

#13

Great writeup! Thanks for sharing.

#14

Ok so here are some updates, I finally got my PB big brake kit and installed it, I also installed bolt on fender flares and wider wheels and tires. I am also in the process of getting and installing a good set of fully adjustable coilovers for it so I can finally enjoy it without having to worry about rubbing because the stock shocks are way to bouncy. So here are some pictures of the progress.
Here is the 2 piece 380mm disc.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/A5B7FD4C-9401-4FED-B0E0-26D5E65F6044.jpg

Here is the 8 pot calipers.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/DAA7CB1C-37E1-4B47-998A-A5C58DD0DE2B.jpg

Here are the brakes installed on the car.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/12088225_10153831350106833_2090418236413435405_n.jpg

Heres the brakes behind the mounted wheels.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/brakes.jpg

Heres a picture of the engine after I installed the JHM S4 intake elbow. I had to make a custom bracket to hold the elbow on because everytime I accelerated hard the tq of the engine would cause the pipe to come off of the throttle body. FYI the S4 intake elbow is not a perfect fit and I had to custom fit it with some other pipe and a additional coupler.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/fender%20and%20intake.jpg

Ok here a picture of the front of the car when I installed the first set of fender flares but realized they did not completely cover the tires so I had to order wider flares.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/fenders%203.jpg

Here is the new flares mounted looking from the front.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/fender%20flares%201.jpg

And a couple from the rear.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/fender%20flares…jpg

http://i228.photobucket.com/albums/ee159/sugerdady20012001/fender%20flares%202.jpg
 Ill admit its not for everyone but I love how it looks and soon It will sit a little lower with a set of these.
http://i228.photobucket.com/albums/ee159/sugerdady20012001/12294775_10153915396306833_885288809094068678_n.jpg