K&N Air Filter

Nooooo... don't do it. Unless your car is a lease that you are going to be giving up. And even then, don't do it because some poor sap like me will get stuck having to figure it out and fix it.

I know I will probably be flamed for saying it, but unless you are using it in an application where you are tearing down the motor frequently it is just a bad idea. You may not have any problems for a long time - 50k miles or more, and you probably won't notice the problems you create even then, but you are not doing your engine any favors.

These filters do not filter as well as regular filters. I spend a lot of time working on turbo diesel cars and trucks which demonstrate beautifully how much dirt these filters let in.

I have replaced (a lot of) turbos because they have had their compressor wheels sandblasted to nothing by the dirt coming in. I have seen f350's show compressor wheel damage starting as soon as 5000 miles after using them. It was an extreme situation granted...

We don't have turbos, so our cylinder walls are where the problem manifests itself. The dirt will wear down the surface of the cylinder walls and the rings and then you will start burning oil. If it clumps or bakes in with the carbon, it can also scratch your cylinder walls causing lower compression and burning oil. It can also contribute to rings sticking. This can get nasty in worst case scenarios. I've seen the Ford gas V10's suffer that way.

 

Ditto what ragman said. I had one in my old 87 Turbo Volvo for about five years (80K). When the Turbo seized and I pulled the inlet hose the compressor wheel was coated with greasy dirt. Replaced the turbo and tossed the K&N.

I dumped the car over 123K miles later and had run a paper filter since day one with the new turbo. The inlet compressor wheel looked brand new the day before I clunkered it.

I tell everyone I know when you go look at a used car if you see a K&N sticker on the air box or see a K&N filter in the air box walk away from the car.

I know people who swear by them and that is fine but I will never again put one of those filters in my car. I drive cars for 200K plus miles and they have to last. Synthetic fluids and only paper OEM air filters for my cars.

 

Agreed.

Plus you risk fouling your MAF. Not to mention that any increased performance (assuming there is any) is so minimal to be a rounding error that won't be noticeable in real life.

 

^This

I highly recommend against it.

 

Good information. I was thinking of getting one too......glad I didnt. I was under the impresion they were good quality.

 

You may attempt K&N in other cars but not on Prius. Prius is not particularly a sports car and the startup/running/shutdown are are controlled by something else.. IMHO

 

Air filters make zero difference in MPG for OBD II cars. See this Oak Ridge National Lab test paper on the effects of clogged air filters on MPG. Zero difference for OBDII closed loop engines, which have been on all cars sold in the USA since 1996.

A low restriction filter or no filter should allow for slightly more wide open throttle power (WOT), but this would only be useful on the track, or for racing. The downside is that these filters are less effective at filtering particles (see so many UOA over at bobistheoilguy.com for raised silicon on low restriction filters) and the previous posts talking about gummed up MAF sensors.

Botton line, not only a waste of money, but harmful to the engine. However, it may allow you to win some races you otherwise wouldn't.

Rumple

 

Good to know. I had it on my 05 G35 coupe and also my 98 Acura Integra GSR, but i won't b puttin it on my prius now

 

I have a K&N and have had no problems! I have had it installed for over 50k and have loved it! No problems and it seemed to get a little better mpg besides the fact that you will never buy another filter! A win win as far as I am concerned!

 

I've also herd good things about K&N filters. However, this thread has made me skeptical about putting one in my new Prius. I guess I'm just gonna keep to the stock filters.. for now anyway.

 

I found a new, yet open boxed, filter for my 2013 Prius, I like to think it makes it faster and more efficient. However I did no testing to see whether or not there was any improvement. It was only $20!

 

It is just money. Your mechanic will clean your MAF sensor for cash.

 

2 WORDS - Stay Away. After 2yrs of using K&N, CEL comes on & off. I went to the dealer & was charged $129 to run diagnostic check for codes PLUS $200 to replace Air MAF Sensor PLUS $200 for labor. Went home after paying $129, went on youtube then went to Pepboys to buy the spray cleaner. Problem solved. Total cost? $129 + $4.99 = lesson learned.

 

2 words if you think it makes your car run better...Placebo placebo.