K&N Air Filter

[D.I.S.C.O]

I am thinking about putting K&N air filter in my 09 2.4. I heard that it can significantly improve fuel economy. Does it cause drivability issues? I remember that on my bikes I needed to rejet or the bike doesn't run properly. Thanks in advance.

[engineertwin2]

K&N may improve fuel economy, but that isn't entirely proven. What it does tend to do is increase airflow (and thus HP). Now, if you throttled back because you didn't need more power then you could potentially improve fuel economy. However, the trade-off is that the K&N doesn't filter to the same capacity that the OEM filter does. They attempt to correct this by wetting it with oil, but this doesn't improve filtration significantly and over oiling the filter can foul the MAF sensor.All that said, I have a K&N filter in my Vibe. It's not for more power or fuel economy, but rather for a washable filter (convenience).

[prathman]

I wouldn't expect drivability problems, but everything I've seen about K&N filters indicates that they're not good at actually filtering out fine dust in the air and keeping it out of the engine. I wouldn't expect that to have any noticeable short-term effects, but it would result in increased engine wear and eventual failure - not something I want to take a chance on especially since OEM-type filters are pretty cheap and last a long time. Here's one set of test results:http://getdieselpower.com/misc....htmlNote that the K&N let through 3.2% of the particulates vs. only 0.07% for the OEM. Bob - the Oil Guy found worse filtering performance but in a qualitatitive rather than quantitative test, and I've also seen others report increased levels of silicon in oil analyses done after putting in the oil-type K&N filter - that shows that fine sand (silicon dioxide) is getting into the engine oil. Not something you want to have slowly grinding away at your valves and cylinder walls.

[djb383]

If a cotton gauze filter was so great and would improve fuel mileage................why wouldn't the auto manufacturer install them????? How easy would that be???? Aftermarket marketing departments wouldn't lie to you.......would they?

[kunkstyle]

Quote, originally posted by djb383 »If a cotton gauze filter was so great and would improve fuel mileage................why wouldn't the auto manufacturer install them?????Because paper filters are cheaper. Why doesn't a washable filter come with home furnaces?

[bull77]

I used to have the K&N drop-in filter for the same reasons engineertwin2 said. I didn't see that much improvement in mileage.Now I run a K&N cone filter and notice a little better mileage and acceleration is faster.

[djb383]

Any verifiable proof would be great.

[BlueCrush]

I'm currently using the aFe Pro Dry-S drop-in filter. It is a dry filter that is washable. I love it! It provides better flow then the oem filter without having to worry about oil fouling out the MAF. Only problem is they don't offer it for the '09 Vibe yet., but it is something to look out for in the future if you are waning a high flow dry drop-in filter replacement.http://afefilters.com/prodrys/v1.html

[Digger]

A washable filter means less trips to the dealer to buy all there goodies, Talk about a new vibe and all the sales they have. .....

[djb383]

K&N filter oil screwing up a MAF sensor is a MYTH......right up there with don't use synthetic oil in a new engine.http://www.knfilters.com/MAF/massairfindings.htm Paper filters are somewhat cheaper, however, if a cotton gauze element gave better fuel economy and equal filtration, the car manufacturers would be buying hundreds of thousands of them a year, thus bringing the cost way down. The public and the government are screaming for better fuel economy so again, if cotton gauze gave better fuel economy what could be easier. I think the automotive engineers see through the smoke and mirrors of most aftermarket marketing departments.

[harryyiii]

Manufacturers don't use oil soaked filters because they are MUCH less efficient. Paper filters work by having passages so small that only the smallest particles can get through. That is why the pressure drop is so high. Oil soaked filters work by trapping dirt on the oil surface. You have to hope that the dirt hits an oil soaked fiber. Most particles don't. This is the same technology as the crappy furnace filter that isn't worth a darn. Dirt in the engine, not a good thing.

[prathman]

Quote, originally posted by harryyiii »Manufacturers don't use oil soaked filters because they are MUCH less efficient. Paper filters work by having passages so small that only the smallest particles can get through. That is why the pressure drop is so high. Oil soaked filters work by trapping dirt on the oil surface. You have to hope that the dirt hits an oil soaked fiber. Most particles don't. This is the same technology as the crappy furnace filter that isn't worth a darn. Dirt in the engine, not a good thing.Agreed. In the test report I cited above, the K&N filter let through about 40 times as much dirt as the paper OEM filter. It also clogged much more rapidly. So it was more free-flowing when new or just cleaned, but that advantage was rapidly lost and you'd need to clean it many times as often as you replace a paper filter to actually have the benefit of less resistance to air flow.Reason enough for the car makers (and me) to continue using paper filters.

[engineertwin2]

Quote, originally posted by djb383 »K&N filter oil screwing up a MAF sensor is a MYTH......right up there with don't use synthetic oil in a new engine.http://www.knfilters.com/MAF/massairfin ... ..properly oiled filters won't allow oil migration. However, improper (heavy) applications of filter oil can and will migrate.

[djb383]

Quote, originally posted by engineertwin2 »Agreed...properly oiled filters won't allow oil migration. However, improper (heavy) applications of filter oil can and will migrate. ...........and K&N purposely soaked MAF sensors in K&N oil with no ill effects. Again, pure myth about damaging/effecting MAF sensors.

[engineertwin2]

I guess I didn't read it all...I will accept this information, but prefer to see independent tests and not tests by the company that stands to gain (this is why I can't stand RP).Still, one can argue that there is a seemingly higher MAF failure after installation of some filters. That being said, I've seen no info on it.

[irishroach77]

when i put in my K&N cold air intake you could feel the slight increase in horsepower, as for gas mileage it definately helped. I have had it for two years and have only had to clean it twice so far and it seems to be working great still

[pick41]

Quote, originally posted by prathman »I wouldn't expect drivability problems, but everything I've seen about K&N filters indicates that they're not good at actually filtering out fine dust in the air and keeping it out of the engine. I wouldn't expect that to have any noticeable short-term effects, but it would result in increased engine wear and eventual failure - not something I want to take a chance on especially since OEM-type filters are pretty cheap and last a long time. Here's one set of test results:http://getdieselpower.com/misc....htmlNote that the K&N let through 3.2% of the particulates vs. only 0.07% for the OEM. I know where you're coming from on this one. I switched out my K&N to a Stage II AFE dry intake system on my CTD. But where talking diesels. So the oil, and larger particals would go from the filter to the Turbo, maybe causing bigger problems. Proir to that I always ran K&N's in everything. Now, just keeping with the stock filters. The Mod bug has passed.