Project A4

[ScottyB]

decided to finally do some DIY work on the airbox today (the kicker was the 80 degree temps this afternoon!). the stock box flows pretty well to begin with, but by removing all the baffling and crap, it will actually flow better than a cone filter...plus it recieves air through a ram at the leading edge of the hood, so it can get a cold air source.


here is the bottom portion of the stock airbox. look at all that junk. it's like a party in my airbox!1!1!!! up front is the coarse screen to catch big stuff, then bracing (no idea why it's there, the plastic of the box is rock hard) and a weird flappy thing towards the back.





here's the top half. it stayed unmolested for now, until i can get a flexible dremel attachment (more on that later)



damn Germans making everything so complicated. no clue why this is here. it's definitely not to prevent water congestion, because the main opening is higher up than this is. the spring that loads the flap is really stiff too, so i can't imagine the engine pulling enough vacuum to open it. so, out it goes.

closed


open


the violators get the boot.


chiseling the reinforcements was way easier than using the dremel (quieter too). i also found that the angle of attack i had to take with my dremel was too steep....i'll have to get a flexible attachment later. this prevented me from doing anything to the bottom part of the lower airbox portion at all.


smoofed. had to use plain old sandpaper, so much for tearing it up with the dremel.



looking at the first shot it's easy to see how much clutter there was. while i was taking the airbox out i found some cold start emissions lines that had rotted out from the heat. those got cut and plugged. eventually i'll smooth the entire inside out, and make provisions to run the intake to either an NACA duct in the bumper, or to a passenger headlight housing that i will make into a ram air duct (like Dave's MkIV headlight).

from a brief drive, i've noticed that the engine sounds deeper and the bypass valve really lets out a nice wooooosh sound. so, ah....all i can say is that it's louder. without a boost gauge, i can't tell if my spool is sooner (if that's possible) or if i gained anything, but going from other A4 enthusiasts who have logged the results, it should be an improvement. down the road, when i go with a bigger turbo the new airbox should be a solid improvement over trying to maintain the use of the stock box.