How much added benifits do actually get from K&N air filter

No, there is no performance or MPG increase

You run the additional risk of fouling the MAF sensor and TB.

 

I wouldn't put a K&N on a car with an MAF sensor. They can actually ruin the MAF beyond the point of cleaning.

 

K&N has never been provided any evidence of a MAF sensor being fouled by filter oil regardless of how much oil was used on the filter. We have tested over 100 MAF sensors allegedly harmed by filter oil and have yet to find any trace of filter oil on the sensors. What we did find was that 60% of the sensors in question were performing perfectly with no defect and had in fact been misdiagnosed. 18% of the sensors had complete electronic failures in no way due to contamination while 22% were out of tolerance. Again not a single one had a trace of filter oil on it. For more information on this issue and K&N’s consumer protection pledge go to knfilters.com K&N is proud to have complete quality control by doing our testing, development and manufacturing in the USA. Not only have we sold in excess of 20 million air filters worldwide but we continue to be used by many top racing teams including the winners of the 2007 Baja 1000 and Baja 500 (and the 2008 Daytona 500).

 

There are enough anecdotal reports of MAF fouling. Depending on the location of the MAF, it could be a non-issue or a big issue

I used to have a 1990 4Runner with the 3 litre V6. Put on the Downey intake kit, which replaced the regular air filter box with a K&N conical filter. That vintage 4Runner used a vane mass air meter

Let me tell you that after a couple of years, my vane mass air meter started to stick. The oil residue was in it. Had to clean the vane meter every year or so

I have a K&N universal round open element on an early 80's Ford pickup at my hobby farm. It has an Edelbrock carb, and an oily residue is easy to spot on the carb bore and choke plate. Doesn't seem to impact how the carb works or how the truck runs

As far as using the K&N filter on a hybrid car, care to provide any results of your testing such a filter on a 2004-2009 Prius? Just curious if there are any documented power increases or mpg improvement

 

Hi KN, first-time poster! I assume you are associated with the company. Because my use of the K&N in a 2001 Prius was associated with small (but detectable) increases in particle ingestion (by used engine oil analysis), I have suggested that other Prius drivers keep an eye on the situation with UOA. Any comments on that? Thanks.

 

While there is no MPG increase, there is a performance increase especially at WOT. This is perfect for when you need to pass. MAF fouling will only happen if over oiling the filter, after cleaning it. The biggest gain you get from these filters in a Prius, is that you can use them over and over again after a proper cleaning. Plus they filter better as they get dirty.

 

Never had a problem with is on my Nissan. And there was a very noticeable and measurable performance improvement (around 0.5 sec 0-60, roughly the same for the Accord, but it had a MAP set up.)

With the Honda Accord VTEC we noticed a substantial change in the smoothness of the throttle response--it had more of a staged feel before, either pulling hard on the VTEC cam, or lugging when off of it with no sweet spot for normal acceleration. Afterward there was a wide sweet spot for moderate acceleration.

With the Prius you should get a bit more air at WOT and this should translate to a bit more power when you want/need it. In the mountains this could be especially beneficial since the atmospheric pressure is already reduced due to elevation, and because long steep grades will deplete the battery assist.

I would not expect any MPG improvement. This is because the throttle valve controls and restricts the extra available airflow in all but near wide open throttle conditions, and the oxygen sensor/MAF system keeps the mix stoichiometric.

 

I had a huge performance increase with my 4Runner across the entire power band. That vintage 3.0 V6 had a weird way of getting air, by sucking it from around the headlight bucket.

Even with the conical filter sucking in hot engine bay air, there was an extremely noticeable difference in off-idle to WOT. When I ditch the factory crossover pipe and EGR reed valve assembly for a Downey crossover, with Downey ceramic coated headers and a Borla cat-back, that thing really woke up. I even gained a couple mpg

I really don't see how one can gain with a Prius. I would like to see dyno results of before and after, please

 

I would like to see dyno results as well, but I'm not sure how one would do that with a Prius considering its drive system. Someone with a scan gauge could do some back-to-back 0-60 runs with a given SOC. (And for any mpg claim one should at least do several ~30 mile back-to-back cruise control runs.)

I did have some 3rd party dyno tests for my Nissan, but the K&N outperformed these figures--and the Borla cat-back underperformed. The headlight snorkel was an issue.

As for power, It really depends on how much restriction the factory air filter produces vs. the K&N at WOT. I wouldn't expect much for the Prius, but I would expect something.

 

NHW20 Prius has been dyno-ed, and reported on PriusChat a long time ago. I suppose they ran it in inspection mode.

 

I had a K&N 77-series intake on my Tundra V8 and with the Flowmaster and 3 inch exhaust, at WOT it was extremely loud and even got a little but of a whine. I did notice some minor performance (butt dyno), but the main reason I got it was because it was used at least monthly in the desert at high speed and replacing paper filters was getting old.

 

I just tap the dust out of a paper filter if I run in dusty conditions. This is a good thing about paper filters. You can actually was paper filters.
I'd use a Donaldson filter before I use an oiled filter. Earth moving equipment which do thousands of hours in the dirtiest conditions use paper filters, race cars which are rebuilt every few hours may use K&N.

I'll stick with the Toyota filter housing and elements. That's what I think.

 

I have a K&N filter in my Jetta, Prius, and BMW motorcycle. I didn't notice any performance advantage, I simple bought them to reduce the waste of throwing out a paper filter every 30K miles. When I run out of cleaning fluid and oil I will probably go back to paper filters.

Cleaning and oiling a K&N filter correctly is a pain. First you spray the cleaner on the filter and rinse it out. Then you have to wait for it to dry completely before spraying it with oil. In a humid environment like Alabama it can take an hour or more for the filter to dry. So what is a two minute job with a paper filter is a 1 1/2 hour job with the K&N.

 

JSH has very good points. I used a K&N in my 2000 Jetta and when the air sensor messed up the VW dealer accused me of "over oiling" the filter...replaced my K&N and sensor and charged me $400...I'd never had the filter out to oil..8 months later I received a recall on the sensor and ultimately refund of my $.
Lesson...be careful with the oil or better still, just stick with paper.

 

This also is my policy, the Toyota filter element only costs US$13 (plus shipping) so this is not a big financial deal for me to replace every 15K miles.

I hope not, since this mode only allows 2,500 rpm max engine speed.

I recall that my dad owned a 50's vintage Plymouth with an oil bath air cleaner. What a PITA; when paper air filters were introduced this was considered to be a big advancement. I don't see the attraction in going back to the past.

I've also seen a few posts from Classic owners who reported similar problems and had to pay for MAF sensor replacement. Since the Classic air filter is located directly above the MAF, it is easy for this to happen.

 

Good point. If K&N oiled filters are so good, why don't million dollar equipment run them? Maintenance costs a small fortune on such machines, you'd think if they could save money by not throwing away paper filters ...

The tractor at my hobby farm has an oil bath pre-cleaner and a paper main filter. The two working together appear to do a good job. It's a disgusting mess to clean the oil bath precleaner

The example of my 1990 4Runner is fairly unique. It sucked in all the air through the headlight bucket. I only wish there had been a non oiled filter alternative, as even sucking in hot engine bay air was an improvement for that 3 litre V6

I've noticed the person who purported to be from K&N Engineering, has not returned. Hmmmm ....

 

The K&N person's point was valid. The mass flow sensor stuff is FUD from what I've seen.

Jayman, my 240's air intake was behind the headlight bucket as well. Sucking warm engine bay air was a problem in Texas in the summer, but the car still made more power that way. On a cool evening it had a LOT more power.

As it is, the K&N is to give you more flow and this usually translates into more power. Since the body of the car will end up worn out/totalled before the engine wears out in my experience, I'm willing to trade the potential for slightly increased engine wear. In the two vehicles I've used a K&N in this has translated into exactly $0 of additional maintenance cost and 0 days of reduced vehicle lifetime.

Cleaning the elements does take a little time, but the performance improvement was worth it to me on my other vehicles. I would do it during one of the oil changes so it was no big deal to let it dry. I certainly wouldn't bill the K&N as a time saver. Overall it was like getting a nearly free engine upgrade.