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FN2 FN2 airbox mod

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41
So today, having a day off work, i decided to carry out my first modification in just over 3 months of owning the car. I didn't want a full induction kit but was quite intrigued by what i had read about the airbox mod'. First i got myself a K&N panel filter. Then after removing the airbox, a 5 minute task, i dug out the Dremel.
The first thing i realised was that i wish i hadn't been a tight arse and had paid for the flexy dremel extension as without one progress is limited. That didn't put me off though and i removed all i could. The larger of the cutting discs make good progress of the obvious bits and the smaller discs for the more intricate parts. However, those discs shatter very easily and cause a lot of the plastic to melt causing quite a mess. The grinding heads and sanding wheels are next to useless for finishing as again, they just melt the plastic and bond it to the Dremel accessory.
After removing all i could using the Dremel i then used a snap blade Irwin knife to trim off other bits. I heated the blade up to ease it a bit. This made light work of it and got loads of bits out. Then it was the turn of 60 grit yellow oxide to smooth off all the cuts and edges. After lots of sanding and sore fingers it was getting very smooth. Finally, i got all the sanding marks out with 5 stages of wet and dry, starting at 400 and going up to 2000. As Brian Johnson would say, it was as smooth as a gravy sandwich!
In total, all the cutting, sanding and polishing took a total of 6 hours. It's clearly not a job to be rushed.
Possibly the toughest part of all was refitting the lower airbox. It just refused to sit in its mounts even after applying grease to the brackets and heating up the mounts. I had to trim the brackets a bit to ease it in which worked a treat.
Now i must admit, i'm sceptical about any gains so i don't expect any and wont start raving about better mid range, quicker acceleration blah blah. I didn't even expect much difference to the sound but for the price and time involved it was worth giving it a shot.
So after starting it up and driving off the first thing i noticed was that the kangarooing felt a lot less pronounced. There was still a hint of it but nothing like im used to. Good start. After letting it warm up i then gave it some full throttle. I was shocked, genuinley! The noise is brilliant. Somewhere between standard (low revs) and a full induction kit but not quite as loud. It has a great bark to it now and even at low revs if you go full throttle you can hear it sucking in the air. What a great result. Time spent well!
Excuse the lack of photos, it's not my thing and i'm sure you can find pictures on google - i did and that's what i used as referance. So if anyone else is considering it then on sound alone i can highly reccomend it!
 
Removed all fins from the box, touched no other part of the intake system. Literally copied a photo i found on here and google . (Loxy's, i think)
 
Removed all fins from the box, touched no other part of the intake system. Literally copied a photo i found on here and google . (Loxy's, i think)

I'll have to have a look but after a long weekend I'm being lazy so I'll ask here... do you cut all fins from the air box top & bottom? I've read somewhere that some fins should be left in?
 
Chris, you don't remove the fins from in front of the maf housing. Here's mine from a few years ago.
 

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Chris, you don't remove the fins from in front of the maf housing. Here's mine from a few years ago.

Yes, thats it! Thats how i trimmed mine but then removed every last bit so the surfaces are nearly glass smooth!
 
Sorry what does this achieve ? Interested as i replaced a imo terrible intake to standard.

The standard airbox was designed with a few things in mind, some of which compete against one-another. It has to provide decent airflow, but balances that off against minimal (induction) noise. The mod increases airflow a little by removing the fins which provide a little turbulence to the airflow and reduce the noise.

With the fins removed there's more of a bark to the noise and a slight improvement in flow if I remember correctly. It slows airflow through the box and prevents that flow from being directed specifically at one part of the filter. It might also act as a slightly larger intake plenum and all that concerns, but I'm not 100% on that aspect (since it's before the throttle-body).
 
The standard airbox was designed with a few things in mind, some of which compete against one-another. It has to provide decent airflow, but balances that off against minimal (induction) noise. The mod increases airflow a little by removing the fins which provide a little turbulence to the airflow and reduce the noise.

With the fins removed there's more of a bark to the noise and a slight improvement in flow if I remember correctly. It slows airflow through the box and prevents that flow from being directed specifically at one part of the filter. It might also act as a slightly larger intake plenum and all that concerns, but I'm not 100% on that aspect (since it's before the throttle-body).

Sounds good, so there's no detrimental affect to removing the fins? i'm really not bothered about noise, I want practical performance. If chopping the fins made it louder but slower I'd leave it alone!
 
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