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MNBoxster · 09-24-2005, 10:51 PM

Hi,

The K&N and other oiled cotton gauze filters have been known to contaminate the MAF sensors, not the 0² sensors. Whether too much Oil was used is a possibility. But, there are several other reasons why the K&N Type Filters aren't a good choice.

A couple points which must be made:

A K&N Filter does let in more air, but also more dirt - 18 times more in the test linked below. This stands to reason, because the only way you can let in more air from the same sized Filter is to have bigger holes in it.

And, most stock air filters (if in servicable condition) are already capable of flowing more air (CFM) than the engine can use - about 99% of them. So adding a Filter which provides even more air is redundant.

While there are some Dyno Reports which show a modest HP/Torque increase with K&N and some other Aftermarket Filters, most of these have incorporated the use of the Aftermarket Filter as a compliment to other modifications such as porting, polishing, swapping injectors, ECU Upgrades, Header and Exhaust modifications, so these results are fairly tainted.

Even those very few which show advantages from the Aftermarket Filter alone are misleading. If you look closely at the data, the increases usually exist only very high in the Power Curve, and then usually with a corresponding decrease in the mid-ranges (where you normally drive).

Also, if you look at the test data linked below, pay particular attention to the Time to Restriction Test. This indicates that the K&N became restricted in 1/3 the time of the leading paper filter. This means that in just a few thousand miles, the K&N actually underperforms the Paper Filters and relinquishes any moderate HP gains it may have.

Finally, since most of the dirt which passes through the Filter, any Filter, ends up in your Engine Oil, using a Filter which passes 18 times more dirt means that you have also considerably shortened your Oil Change Interval (if you're interested in preserving your Car's Good Health).

No, there are few difinitive tests (if any) which show the Aftermarket Filters to be superior. But, there are several tests which show how inferior they actually are. One of the best is here: http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

This should pretty much end the argument!

Happy Motoring!...Jim'99

09-24-2005, 10:51 PM	#2
MNBoxster Registered User Join Date: Sep 2005 Location: Minneapolis/St. Paul, Minnesota, USA Posts: 3,308	Hi, The K&N and other oiled cotton gauze filters have been known to contaminate the MAF sensors, not the 0² sensors. Whether too much Oil was used is a possibility. But, there are several other reasons why the K&N Type Filters aren't a good choice. A couple points which must be made: A K&N Filter does let in more air, but also more dirt - 18 times more in the test linked below. This stands to reason, because the only way you can let in more air from the same sized Filter is to have bigger holes in it. And, most stock air filters (if in servicable condition) are already capable of flowing more air (CFM) than the engine can use - about 99% of them. So adding a Filter which provides even more air is redundant. While there are some Dyno Reports which show a modest HP/Torque increase with K&N and some other Aftermarket Filters, most of these have incorporated the use of the Aftermarket Filter as a compliment to other modifications such as porting, polishing, swapping injectors, ECU Upgrades, Header and Exhaust modifications, so these results are fairly tainted. Even those very few which show advantages from the Aftermarket Filter alone are misleading. If you look closely at the data, the increases usually exist only very high in the Power Curve, and then usually with a corresponding decrease in the mid-ranges (where you normally drive). Also, if you look at the test data linked below, pay particular attention to the Time to Restriction Test. This indicates that the K&N became restricted in 1/3 the time of the leading paper filter. This means that in just a few thousand miles, the K&N actually underperforms the Paper Filters and relinquishes any moderate HP gains it may have. Finally, since most of the dirt which passes through the Filter, any Filter, ends up in your Engine Oil, using a Filter which passes 18 times more dirt means that you have also considerably shortened your Oil Change Interval (if you're interested in preserving your Car's Good Health). No, there are few difinitive tests (if any) which show the Aftermarket Filters to be superior. But, there are several tests which show how inferior they actually are. One of the best is here: http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm This should pretty much end the argument! Happy Motoring!...Jim'99 Last edited by MNBoxster; 09-25-2005 at 04:33 PM.