Has anybody done this?

"Another data point sure would have been interesting: a K&N or other non-paper filter in the stock box. As I calculate, the panel in the stock `05 airbox has just about as much surface area as any cone filter used by the aftermarket intakes

My guess is that it would give at Least half the benefit of a Helix type at 20% of the cost.

The Alta results also make me wonder how the stock airbox would do if the accordian hose was replaced by a smooth intake hose?"

(-OldRick from the Intake shoot-out thread)

I'm wondering what power gains anyone has seen and whether it sounds any different (SC whine) than stock or cai

 

Yes...somebody has done this. Namely me. I have a K&N panel filter replacing my stock MCS filter.

Definitely more engine growl. It's louder even at idle so the supercharger whine is harder to hear.

I noted smoother midrange and higher rev response on my engine but am not sure if it is because my stock air filter was just a mess (read dirty). The car was just over a year old at the time I changed over.

I can't really tell you if there's more power but I have noticed a bit more torque steer when starting from a stop and I do chirp my tires more. Any actual gains in acceleration times, I would think are marginal.

Other than the filter area of a cone filter being comparable to a panel filter, the other issue would may be the efficiency of airflow from where the air enters the car (from the front and through the cowl), and changes direction to flow through the filter to the throttle.

I am of the impression that a replacement drop-in filter may allow for better response to changes in throttle position. Due mainly to less resistance. However, as the hoses and any other parts are not replaced, the volume of air going through remains the same so you probably do not get any significant increase in power.

A drop-in filter is cost effective in that they don't cost a whole lot and are reuseable. So other than the cost of a cleaning kit, a K&N filter would be about 3 stock air filters and will last as long as you own the car.

Someone else have any other input?

 

Although the volume might not change, if there is less resistance to flow, wouldn't the density of the air be higher and thus increasing your airflow, and therefore power?

 

I'm not too sure about that. Kind of like a venturi. The speed of flow increases at the point of restriction but the volume doesn't. The increased speed of flow at the filter, in my opinion probably reduces the turbulence of air going in to the throttle so provides a more stable volume of flow at steady state. When volume is changing (ie..lefting your foot off the gas pedal or stomping on it), the change in airflow happens faster.

Of course this is only theory based on some physics and and chemistry I took in first year university...oh...20 years ago.

On another note to that, I haven't decided if the better performance could be due to the fact that my old filter was simply filthy. Will have to wait a few more months for the K&N filter to get really dirty first.

 

well yeh if i was gonna keep my stock airbox (for stealth) i'd get a panel filter too.

But surely it's not unlike sucking air through a straw. More restriction means that less volume comes through per unit time (same velocity of moving air), so there less air available to the SC.