K&N Filter

I have a 2003 C4S. Would installing a K&N filter be advisable? Any noticable increase in sound or horsepower? Thanks

I have the Fabspeed airbox modification, and a K&N airfilter (and exhaust & headers), the difference is not very noticeable. I would highly recommend getting the ECU reworked & K&N powercone unit. EVO Motorsport in AZ has that package. The 996 really benefits from ECU modification vs. standard power adders, as I think it's already very well tuned in stock form. You need to tweak the electronics before you get much added benefits.

The efficiency (tested at WOT and Rev limit) of the OEM filter is in the range of 93%, 7% "loss". The K&N increases air breathing efficiency by 70% over OEM increasing overall efficiency to 98% So your total air breathing efficiency gain is ~5% and that's only at full air volume flow, max RPM and WOT.

I thought it was not recommended since it will affect the Mass Air Flow sensor which is very expensive! Waz

i originally bought the K&N powercone kit but returned it because i figure a drop-in K&N filter would do the same thing. The air box is already cold air designed via the deck lid grills. They also don't make a water guard for the 03 c4s's which made me worry about the rain

I think the MAS is OK unless you over oil the filter after cleaning it, the extra oil then damages the sensor.

ive been using k&n filters in all of my cars including my past 996 and current and have had nothing but success

NiveK I've been using nothing but OE filters in all my cars and have had nothing but success also. And.... How do you NOT over oil the K&N?? An oil trap downstream?

Is that question for real or a joke. Oil based filters when cleaned need to be sprayed with oil again... not over oil means don't leave it soaking with oil after cleaning it., i.e. follow instructions.

Curves4s, I was going to do the exact same thing on my car but was talked out of it by a very well known local Porsche racing team. Whatever gain in HP you achieve at the motor may not necessarily transmit to the wheels. The only way to find out is to put the car on a Dyno, and from what I was told there is no appreciable increase. The difference is sound, however, is another story. For what its worth....

The stock airbox design closes off about half the actual airbox, so I can see how the Fabspeed helps open it up quite a bit. I have heard on this/other websites how the stock airbox flows more than enough air for the car under current settings. I put my headers and exhaust on at the same time so sound was boosted substantially. But if you tweak the ECU, then it is able to use the increased airflow of power cone or Fabspeed unit. Please beware though that the powercone unit went through 3 designs. The first 2 units actually lost hp, until the 3rd design. The Mass air sensor issue is because of excess oil on the K & N unit fouling the sensor. If you do get it I would suggest that you open the package on leave it over newspaper for the night. Also everytime you re-oil the unit do the same thing.

i have the power cone on my car. i have no idea what the dyno numbers are with it on, but i have two things to say. 1. If you drive in the city then it will probably decrease your HP because it'll be sucking in hot engine compartment air. 2. If you drive on the highway it will become a true cold air intake because at highway speeds the hot air is flushed from the engine compartment. The best way I can prove this is that when I stop my car after driving on the highway, the aluminum shield over the bottom of the stock airbox is ice cold. About the MAF: If you oil the filter correctly you should have no MAF issues. The filter I got had too much oil on it and I wrecked my MAF. Fortuneately my car is under warranty so I just put the stock airbox back on, cleaned the MAF, and took it to the dealer and played dumb. They replaced if for free. I then completely cleaned the filter with a K&N cleaning kit and reoiled it and had no problems. I'm actually considering switching to the Fabspeed intake instead of the power cone since I do a decent amount of city driving. I do LOVE the intake sound of the power cone though. I've also heard that K&N filters aren't the best route and that BMI makes a better one. But I really don't know....

K&N and Over-oiling.... IMMHO the only way to prevent over-oiling, and thereby fouling the MAF, is after oiling place it in a makeshift windtunnel with airflow approximating that of the vehicle at WOT and max RPM for 24 hours. But then there may not be any oil left afterwards, just like what happens in the vehicle.