Cold air intakes (K&N or EVO) vs. modified stock thoughts

I actually posted this as a response over on 6speed, but thought to create a new thread so I wouldn't aggravate everyone in the K&N horsepower challenge thread. After looking at the dynos, I'm just wondering if a freer flowing K&N/BMC replacement filter in the OEM airbox wouldn't product similar results and for an even greater discount. I guess my question is: how is the air getting into the throttle body any faster with this 360 degree air filter even though it's using the same snorkel to suck in air. Moreover, wouldn't the stock airbox 'truly' be cold air since it's sealed (read, no cracks or potential leaks to hot engine air like both cold air kits that don't seal perfectly well with the engine lid)? Essentially, putting in a K&N flat but free flow replacement air filter and disconnecting the smog/noise restrictor (the teeny little second hose off the airbox) seems like it would be a pretty good alternative. What do you guys think?

I'm not sure if this is specific to the Aero wing or not but on my car there's an additional opening in the rear lid where the fan attaches to the lid. This is directly above the filter area for the K&N unit increasing the available supply of cold air to the filter (although I personally feel this only works at speeds of 60+). Sooooo while the intake also uses the same intake snorkel as the stock air box it's getting air from other sources as well. On the EVO intake it's been noted that the stock location in the deck is used to get air but the track getting the air to the filter is much larger and less restrictive than on the stock box....again benefits over the stock box. Further the air stream in the stock box goes around right angle bends and through a rough tube into the throttle body which is not as efficient as it could be. How bad it really is has yet to be answered. BUT even the Fabspeed kit addressed the intake elbow and replaces it with a smooth piece of hose. For the price of a filter and the smooth piece of hose you could just buy the K&N and give it a whirl. my .02 Andy

That is one of the things I am pondering. This K&N kit is $300 bucks. Just a flat filter (K&N or BMC) is about a $100 and the Fabspeed or Schnell smooth conector combo is about $275. Either the K&N Cold intake is cheap or a flat filter is way to high. NY I think a K&N filter or BMC will change your sound a bit but as Andy mentioned you still have all of the restriction of the standard air box...tight angles and rough surfaces. I believe there is also a muffler of some sort in the standard airbox that if removed can improve sound. I thought I heard that the muffler was to protect the air box in case of backfire; however, I have never heard of a 996 backfiring. This could save some money but not to much less than the K&N kit. JMO

The biggest diffence I notice with the Evo intake and other conical intakes is that I can hear an air sucking sound at idle. I've never heard my stock intake sucking in air at idle.

Here's the thing: I don't know how to interpret that. Does the sound of the sucking mean that it is air constrained or that air is flowing through there that much faster. I'm going to have to write a letter to Mr. Wizard. This is starting to get complicated. Audi and JSA, you guys makes some very good comments vis a vis the price savings.

"It's Definitely Sucking" - Quote from the VW commercials...sorry guys...couldn't resist As for the air sound...I'm not sure it's a sign of any less restriction...I think that it's a lack of sound isolation that you get from open element systems. go out and take the lid off of your stock air box and I bet you'll hear the same sound. Jury's still out for me on the K&N. I really doubt there's any benefit at slow speeds...but I've said it before and I'll say it again...I swear when you get moving and air's coming in that additional hole in the deck that the car pulls harder in 3rd gear. I'm attempting a solution to seal the heat sheild to the lid of my car even better to see if there are any improvements. I asked in a different thread...but are there implications in taking the stock fan off of the lid of our cars? Andy

I agree. They way we used to solve this question in my old car club was to all get together at a dyno shop or 1/4 track, but cleary that's taboo around here.

Yes, I think it would be very, very bad to take the fans off of the lid of our cars. I believe that the fans are there to help evacuate excess heat out of the engine compartment at low speed or when the car is at a standstill. If you remove the fan, you could cause damage if you get stuck in traffic or after you shut the car off when you park in the summer. I think the slight benefit you might get at speed would be far outweighed by the potential risk of damage due to overheating.

The real question is why EVO and K&N don't seal the compartment themselves completely with some kind of removeable cover to facilitate changing filters. I don't understand what the purpose of leaving the air filter compartment open to the engine deck lid is....