anyone using a K & N Filter

Search is your friend. There are a number of discussions on the inherent dangers of running a K&N filter on PC. Most notable is the possibility of fouling one of your O2 sensors.

To answer your question, I have used K&N filters in the past with three of my cars, but with my Prius, I have decided to not use it.

Regardless, there is a strong debate both for and against. You'll have to read up and decide for yourself. Your opinions may differ.

 

no problems on both our prii (2004 and 2005)

combined miles driven over 170,000.

I installed a k&n after the 1st oil changes on both (5,000 miles).

just don't over oil the filter and no problems.

curt

 

I'm using K&N on my other car (not a prius) and so far no problems... I decided not to use K&N on my prius instead I ordered one of this...



Tom's online shop

 

@Dmanpizza... had this for less than a week but for now ..... no noticeable gain in power or increase in mpg...

 

I have read several places that if you live in a place with lots of dirt/sand/gunk/whatever then a K&N filter is a very bad idea since the grid is larger allowing more junk into the engine.

I dont think you would see any benefits at all with a Prius though since the revs are not really tied to speed and the car's on time doesnt relate to the engine on time either.

 

I have no personnel experience with K&N air filters but there was quite a bit of discussion on the BMW forums I belong to regarding them. The consensus on those forums is:

1. no advantage to K&N, based on track and dyno tests some of the cars tested seemed to developed slightly more power using the stock air filter - but BMW does have a very effective low restriction air filter unit

2. if you over oil the filter you may damage the MAF (Mass Air Flow) sensor and it will not be covered by your warranty, sometimes the MAF can be cleaned sometimes it needs to be replaced

3. no one knows if they actually filter better or worse than the stock filter units

4. some people like the noise they make which leads them to believe there is more power.

I realize a Prius is not a BMW but a K&N filter is a K&N filter and I suspect the results on Toyota engines would be the same.

 

I've done a lot of my usual internet obsessive searching about opinions and experiences using K&N filters.

It's a big debate in most automotive websites including Honda Fit ones. Being I think in general a younger demographic, Fit "kids" like K&N because they have the idea the increased airflow allowed improves engine horsepower.

Some of the enviromentally minded, lazy or economically focused consumers like the re-useability.

K&N of course says their filters meet OEM standards for filtration. While I like the idea of improved air flow to the engine, and reuseability I think I'm going to replace with a high quality standard air filter when the time comes. I'm taking a very untested, unscientific approach, but it just seems to me that the priority with an air filter must or should be how well it filters the air...and I can't simultaneously believe a reuseable filter that allows greater air flow is filtering the air as well as a filter that might allow less air flow as it ages but is trapping finer particals.

I'll upset K&N supporters, and I could be wrong...but that's my logic and unless someone can give me enough information to change my mind...I'm sticking with it.

 

There are no "inherent dangers" of using a K&N air filter. The purpose of an air filter is to filter dirt, dust, and other contaminants from the air going into an engine. If using a K&N caused engine damage, we probably wouldn't have been in business for over 40 years. Our filters are different because they are made from cotton instead of paper, synthetic fibers, or foam, which can be much more restrictive and rob the engine of power.

K&N filters regularly perform in the 98%-99% efficiency range. We are fortunate enough to have an in-house test lab where we can test our air filters under ISO 5011 test protocol to see how well they work. Also, there is no such thing as "manufacturer's specs" for air filtration efficiency. If there were, car companies would be limiting consumers from making purchase decisions and creating "tying agreements" which violates Federal Trade Commission laws. It's up to filter manufacturers to build a quality product that won't cause engine damage, because if their filter did cause damage the company would be liable.

Many of your questions and concerns are discussed and answered on our website on the FAQ page.

K&N Engineering, Inc.
Warranty Department
1(800)858-3333
Follow us on Twitter! "KNWarrantyDept"

 

Interesting. But if you are saying there are no manufacturers specs as to air filtration efficiency then when you say K&N air filters regularly perform in the 98-99% efficiency range what scale are you using? 98-99% efficient vs what? Is a two percent filter blow by rate common or acceptable in the industry?

I still can't be comfortable making a purchase based on the fact that it is up to air filter manufacturers to build a quality product because if they don't the company could be liable.

Too many examples of companies not taking responsibilty for quality or safety.

Not saying K&N isn't a great product, or isn't taking responsibilty. I agree that the purpose of an air filter is primarily and first to filter the air going into the engine. So let me know how 98-99% percent efficiency compares to those competing synthetic fibers and foam competitors...because for me personally that's the only yardstick I can use to evaluate whether I want your product vs. another product in my vehicle.

 

Air filter efficiency is determined by testing using ISO 5011 test protocol. This is the standard test used by filter manufacturers to determine how well an engine air filter works. If you look at what some paper filter manufacturers list on their websites for efficiency, you'll notice that some companies don't state anything at all, and of the companies who do state efficiency, I can find name brand filters with advertised efficiencies as low as 96% and as high as 99%.

This situation (making a purchase decision) is true of other products too. For instance gasoline, there are many brands out there, their products all perform the same function (liquid fuel) and you as a driver choose to use one brand or another. Some people choose brand A because of perceived quality, while others might buy brand B because of price. But your car's manufacturer has no say in what brand of gas you choose to fill your tank with, that decision is yours to make.

K&N Engineering, Inc.
Warranty Department
1(800)858-3333
Follow us on Twitter! "KNWarrantyDept"

 

Thanks for your answers. I guess maybe I should make another trip to your website?

I can't say you've convinced me, but I promise I'll give it some more thought when the time to replace my current filter arrives.

 

Same here regarding my previous cars (and my old G2 Prius). Used K&N, aFe, AEM, etc (you know- oiled filters) and will not be using one on my Prius. I was a long long fan for KN.

So why not on my G3 Prius?

1) I've seen way too many labs (mostly on BMW forums) that the KN is really allowing more dirt particles to follow in. Also some stuff some high silica levels, but this is mostly KN oil filter related.

2) Yes, the KN might be financially wiser in terms of washing vs. replacing the paper filter, but that really depends on how long you keep the car + how often you clean the filter (the cleaning kits are $10-15 each and last 3-4 good washings)

3) I never saw a dramatic gain in MPG. I don't recall how it worked out on my G2 Prius, but it wasn't like a memorable 3MPG gain.

4) No need for extra CFM or airflow into this tiny engine

5) And the biggest one... I'd hate to have Toyota somehow ever blame the filter for something going wrong related to the ICE/air intake/MAF sensors/etc. Yes I know there's a law out there that dealers have to prove cause-and-effect before they could pull something huge like this.

That's just me though.... again, I was a huge fan of KN but not for my Prius.

 

Your post doesn't make sense. Your reasons why you choose to not use a K&N in your Prius vs. your other cars don't sound anything like what other customers of ours say about our filters.

1. A properly installed and maintained K&N filter does not allow more dirt to pass through into the engine than a comparable disposable filter. This is confirmed by ISO 5011 test results which show efficiency between 98%-99%.

2. The K&N is "financially wiser". If you keep your vehicle 100,000 miles and follow your manufacturer's service intervals, you should replace your air filter every 12,000 miles or so. That means you would go through 8-9 disposable air filters. Or you could buy just 1 K&N, which only needs cleaning every 30,000-50,000 miles, and even with the addition of the $15 cleaning kit, still save a little money.

3. MPG gain is not something we advertise or guarantee. There are many factors which contribute to fuel economy which we cannot control, like air pressure in your tires, mechanical upkeep of the engine, and a heavy right foot.

4. Even though the Prius's engine is a small displacement, any engine benefits from low restriction air flow. Yes the OEM filter flows more CFM than the engine can generate, but at what restriction? The K&N is a lower restriction filter which will give the engine better throttle response and more horsepower, so in the driving conditions when the gas engine is providing the power, you'll see better get-up-and-go and crisper response.

5. MAF Sensor contamination by K&N filter oil is a big myth. We have evidence and testing to confirm this. Any dealer which says otherwise is providing bad information.

We are not here to sell or convince anyone to use our products. If you feel that they aren't for you, ok, that's fine. We are only trying to clear up some of the misinformation which is circulating about our products. For those of you who have used K&N filters, we appreciate it, and hope you will continue to be K&N fans. We just want to arm you with the correct information.


K&N Engineering, Inc.
Warranty Department
1(800)858-3333
Follow us on Twitter! "KNWarrantyDept"

 

I speak from personal experience and am glad to see that KN is on the forums to provide their feedback as well. Just stating my experience and opinion. I'm actually still a fan of KN filters, but just not for my Prius. Good info KN.

Edit: While on topic, if anyone wants to see the KN Prius G3 air filter specs. P/N 33-2435

 

Comments in bold below.

 

In K&N's defense even if you follow the link all the way through, they say K&N filters improve Prius performance, well that can mean acceleration and horsepower and NOT mpg's..they don't make any direct claims to MPG improvement.

My further questions would be how does a K&N filters efficiency compare with a "standard" filter with the passage of time? Since it is designed to be used for more or less the life of the vehicle. Is this 98-99% efficiency New K&N filter? How about a restored one? Does the efficiency lessen with time and if so, how much?

Obviously a standard filter will become less efficient with use and time as well but then you totally replace....since this isn't the case with a K&N what's the efficiency of a filter that might be entering it's first, second or even 3rd restoration process?

 

An air filter's efficiency actually increases over time, up to a point. The reason efficiency goes up is because the "pores" in the media where particles could pass through start to become smaller, making it less likely for incoming dirt to make it through the filter. This will occur up to the point where differential pressure causes some of the dirt to become dislodged and be sucked through the filter into the engine. Paper and synthetic filters are typically only 1 layer thick and dirt accumulates across the surface of the media, so restriction builds higher and higher as the filter gets dirtier. With a K&N filter, our media is 4-6 layers of cotton fabric, not a single layer of paper. Dirt actually accumulates by loading throughout the depth of the filter media, as a result the filter will go longer before restriction gets to a point where maintenance is necessary.

The efficiency of K&N filters actually improves a little more after they have been cleaned a few times. Just like washing a t-shirt, the cotton will start to loosen up a little bit after being washed a few times. This causes more filaments to "fray" off the woven strands of fabric, and more fray = more places for dirt to land in the filter. We have a filter currently in testing which has been loaded with dirt, cleaned, reoiled, and tested over 100+ times. It's efficiency is a few hundredths of a percent higher than when it was brand new.

K&N Engineering, Inc.
Warranty Department
1(800)858-3333
Follow us on Twitter! "KNWarrantyDept"