Now I know other people have done simular things with their air filters, but I thought I would post how I did it.
As far as I know, no one makes any kind of cone filter kit for the S2, so I decided to make my own.

A regular tapered style filter like you see on ebay doesn't fit under the header panel (I tried), so I looked on the K&N website to see the different sizes they had.
I picked one that was 7'' long and 4'' in diameter with a flange ID of 2.75''(I picked this because the intake pipe is roughly 2.75''). This filter also has a 10 degree flange angle.
Also, this filter flows way more than enough air for a 3.0L engine (even though it looks kinda small compared to the stock airbox).

http://www.knfilters.com/search/prod...x?Prod=RU-1480

I went to the hardware store and found a PVC pipe angle with a 2.75'' outside diameter. The angle of the pipe is 22.5 degrees.

I "ported and polished" the inside the PVC pipe. Hey, every little bit helps.

Total cost: $38

Reviews so far:
It's hard to tell if there is any performance gain or not.
The sound above 4000 rpm is definately improved.

Pics:

Before:


After:

 

nice work jon, i would love to hear what it sounds like, maybe i'll do the same thing!

 

My PO had a K&N filter that stretched the entire length of the header panel on my car. Definitely a louder sound from the car. Performance wise? I doubt it. The stock filter is so much better then that K&N.

I went back to the stock housing, as the K&N was all ghetto-fied in there. At least your's isn't all hacked up like mine.

 

If all you want is louder sucking sounds this might be a good mod, but it probably removes any resonant effect for the intake (or raises that effect beyond the usable RPM range of the engine.)

In many cases you can get a benefit from increasing the airbox volume (clean air behind the filter) although I doubt that is true with the stock S2 airbox. I suspect the stock airbox fills that empty intercooler space for a reason. Why would you want to eliminate all that wonderful airbox volume?

-Joel.

 

With that mod, you are loosing some of the "ram air" effect of the stock airbox.

-Z

 

on turbo cars, that upper cutout of the front bumper directs airflow into the intercooler. Does that same cutout direct air into the airbox on the S2?

 

There's a type of snorkel that extends down from the airbox -- I believe it is lower than the upper cutout of the front bumper though.

-Z

 

if I had an S2, I would make a duct, similar to what the Turbo cars use, and duct all that air into the stock airbox, using a k&n panel filter. Or is this how they come from the factory? At speed this would create a nice higher pressure area in the airbox. This is worth 10-15 hp on 911's (Porsche says 15, Ruf says 10).

 

The stock S2 nose panel is like that, the IC ducting rams air into the nose area, and the outlets behind where the IC was located are sealed.

That is why I always wondered about those extra nose vents some people add to the turbos, since they look to me like they would be in a low pressure area and actually reduce flow (by creating a venturi vacuum) through the IC core.

At any rate the ram effect should still work with this coffee can filter, but the resonant effect would be lost. That resonance can add 5-15% HP!

 

Thats awesome, I've never seen an S2 engine bay in person.

To couter your point that you may still see a ram air effect, since the whole volume under the nose panel is greater than the volume of the airbox, the ram air effect will be less by removing the airbox.

 

After driving it for a while with this cone filter, I may switch back, and see if I can tell the difference.

I basically just wanted to see what a decent aftermarket filter setup would be like. I've read all of the posts talking about aftermarket setups vs. stock, but I wanted to see for myself.

 

how does the panel come off, something you modified or stock?

87951

 

The panel is stock.

It comes off quite easily the 2nd time. The first time I did it, it wasnt as easy.

There are instructions how to remove the panel on www.clarks-garage.com under "Nose Panel".