K&N's statement on their filters' ineffectiveness at filtering

[FuzzyDunlop]

As I posted, it's not an air "resistance" issue, it's a resonance issue.

Engines are pulsing instruments and with various length and width pipes on the intake and exhaust and various RPMs, you will approach resonant nodes or harmonics that reduce restriction for a while, similar to playing a flute and getting the air you're breathing to properly match the resonance of the flute. When you hit it, BAM, you've got smooth air flow and music. Filters have little or no effect on resonance.

Exhaust test-pipes that "make power" generally do so for the same reason, because they improve the resonance of the exhaust line. That's why "high-flow" cats rarely make power. They only change blockage, not resonance issues.

You can find dyno videos on youtube of people building experiment intakes that are like six feet of solid tubing reaching into the sky. The longer tube gets the resonance down really low and lets the breathing approach more acoustically tuned nodes than a short tube, similar to a pipe organ. They make power that way, but of course you can't actually drive anywhere with one of those things.

Intake and exhaust breathing has more to do with acoustical science than it does with reducing "blockage".

I've read about this before, and find it extremely interesting. Its the same theory for exhaust isnt it? Its why many manifolds have different length piping for different cylinders - it matches the pulses somehow, so that the exhaust moving in the manifold will somehow also 'pull' (vacuum) exhaust out of the cylinder?? im probably way wrong.
Can you find a link to one of those videos?

 

[HybridSquirrel]

I've read about this before, and find it extremely interesting. Its the same theory for exhaust isnt it? Its why many manifolds have different length piping for different cylinders - it matches the pulses somehow, so that the exhaust moving in the manifold will somehow also 'pull' (vacuum) exhaust out of the cylinder?? im probably way wrong.
Can you find a link to one of those videos?

I thought that was the reason for header designs as well, and the reason why there is a difference between equal and unequal lengthed headers as far as power band distribution is concerned.

 

[Throckmorton]

What effect does resonance have on power? And wouldn't resonance only happen at one engine speed and its multiples?

 

[JCH13]

I've read about this before, and find it extremely interesting. Its the same theory for exhaust isnt it? Its why many manifolds have different length piping for different cylinders - it matches the pulses somehow, so that the exhaust moving in the manifold will somehow also 'pull' (vacuum) exhaust out of the cylinder?? im probably way wrong.
Can you find a link to one of those videos?

Most manifolds attempt to have the SAME runner/header lengths. Different runner lengths are generally not great for engine performance.

http://www.team-integra.net/forum/b...e-manifold-tech-runner-size-calculations.html

There is also the effect of helmholtz resonance, where intake plenum volume is tuned to to a certain frequency/engine speed.

There are similar effects with exhaust scavenging, but because the exhaust gases are generally flowing faster and are much hotter than intake gases exhaust headers must be longer than intake runners to be tuned for the same engine speed.


Edit: Adding length/volume to the intake upstream of the throttle body probably doesn't affect either of these phenomena in terms of generating power. Pulling in cold air, will improve power delivery (around 1% per 10*F if your ECU is smart enough to adjust for it IIRC). This sort of power gain is generally not repeatable on a dyno due to air flow issues.

http://auto.howstuffworks.com/question517.htm

What effect does resonance have on power? And wouldn't resonance only happen at one engine speed and its multiples?

It has a small, but noticeable effect on peak torque, but it quite dependent on the particular engine's setup. The way the math works out it is generally impractical to reach anything other than the primary resonance, and some times that's not even practical to reach.

 

[Carfax83]

What are you arguing? It's just a fact, proven by scientific testing, that K&N filters let in much more dirt, 45x according to ISO testing.

I'm not arguing that the K&N filter doesn't allow more dirt in to the engine. I'm arguing that the increase in dirt isn't as harmful to the engine as you'd think, especially if you change your oil regularly like you're supposed to.

High performance air filters are going to allow more dirt into your engine than a stock filter would, but for the most part, it's harmless because it's either burned off or trapped in the oil and filtered.

BTW, I posted a link to a guy that has owned his Mustang for 17 years, and has been using K&N for the entire duration.

He drove through a sand storm for 15 miles and sent an oil sample to Blackstone to have it tested for silicon content, but the test came back normal.

 

[LTC8K6]

I'm not arguing that the K&N filter doesn't allow more dirt in to the engine. I'm arguing that the increase in dirt isn't as harmful to the engine as you'd think, especially if you change your oil regularly like you're supposed to.

High performance air filters are going to allow more dirt into your engine than a stock filter would, but for the most part, it's harmless because it's either burned off or trapped in the oil and filtered.

BTW, I posted a link to a guy that has owned his Mustang for 17 years, and has been using K&N for the entire duration.

He drove through a sand storm for 15 miles and sent an oil sample to Blackstone to have it tested for silicon content, but the test came back normal.

I see no reason to allow it when an OEM paper filter does the job better and costs far less, and requires no additional maintenance.

Not much more air is flowing into my engine unless I make the manifold air inlet/throttle body larger.

It would need to be significantly larger before the stock paper filter couldn't flow enough air for it.

 

[Gillbot]

I see no reason to allow it when an OEM paper filter does the job better and costs far less, and requires no additional maintenance.

Not much more air is flowing into my engine unless I make the manifold air inlet/throttle body larger.

It would need to be significantly larger before the stock paper filter couldn't flow enough air for it.

Exactly, why let that dirt in when there isn't really a noticeable power gain? I've said it before and i'll say it again, when I had my car on the dyno for tuning, we spent a week messing with many combinations and in the end, I made the most power through a paper OEM filter and not the K&N.

 

[jagec]

BTW, I posted a link to a guy that has owned his Mustang for 17 years, and has been using K&N for the entire duration.

He drove through a sand storm for 15 miles and sent an oil sample to Blackstone to have it tested for silicon content, but the test came back normal.

Plenty of people only change the oil every 10k-15k and don't have problems either. But at least they're saving money on oil changes.

Just because many engines are abuse tolerant doesn't mean that it's a good idea to SPEND MORE MONEY to abuse them for no gain.

 

[nyurbiz]

I've used K&N on several vehicles with no ill effects but probably no performance nor gas mileage increases. Just read this as part of information gathering for potential K&N purchase for new vehicle. After reading it I may get a K&N just for the cost savings and reduction in solid waste over the years since there seems to be little difference between ANY of the filters. http://www.bobistheoilguy.com/airfilter/airtest1.htm

 

[Throckmorton]

I've used K&N on several vehicles with no ill effects but probably no performance nor gas mileage increases. Just read this as part of information gathering for potential K&N purchase for new vehicle. After reading it I may get a K&N just for the cost savings and reduction in solid waste over the years since there seems to be little difference between ANY of the filters. http://www.bobistheoilguy.com/airfilter/airtest1.htm

According to that test and the others, there is a significant difference. I doubt there is any benefit to the environment with K&N because you also have to use oil, plus detergents and water to wash. And when it does get thrown away, none of it is biodegradeable


BTW I like how K&N tried to BS the guy...

In the e-mail I received from K&N, I actually got contradictory information on this point. They claimed that the deposit on my test filter was oil (it isn't), and then they said oil does not leave the filter and damage mass air sensors. Honestly, you can't have it both ways. Either oil leaves the filter or it doesn't. Oil will damage a mass air sensor if it gets on the sensor wiring. This is highly documented by TSBs easily available online.

 

[monkeydelmagico]

I've used K&N on several vehicles with no ill effects but probably no performance nor gas mileage increases. Just read this as part of information gathering for potential K&N purchase for new vehicle. After reading it I may get a K&N just for the cost savings and reduction in solid waste over the years since there seems to be little difference between ANY of the filters. http://www.bobistheoilguy.com/airfilter/airtest1.htm

LOL. A little late to the "green" bandwagon but better late than never K & N thread necro troll.

 

[yottabit]

The whole K&N dirt/dust reliability debate reminds me a little of the people who can't believe people overclock their CPUs because of the risk of electromigration

Yeah, it's happening and it's not as good at filtering as a paper filter but for most people that use them they aren't ever going to see the impact of it in the lifespan of the car

That being said it is really a bit of a scam how they over advertise the benefits of it for a N/A car. For most people, the benefits of using a K&N filter just aren't there. And I think as far as the drop in replacement type filters that's true about 99% of the time.

Some cars that have very restrictive intakes can benefit from it but that was more of a 1980s/90s thing, most engines now aren't leaving a whole lot of free horsepower on the table.

The K&N drop in replacement filter's I've bought have been pretty crap. The material might flow ~30% more but usually there's about ~30% less flowable area on them because of the thick rubber around the edges compared to a paper filter.

If you're doing serious modifications to an econocar engine or something then going to a big cone filter makes sense (K&N or other brand), in the situation you need a LOT more flow you need something that's got both more surface area and flows better.

Turbocharged cars specifically is where you see the biggest gains going to a cone-type filter, often times in peak power and slightly reducing boost lag. And obviously if you're upgrading to a bigger turbo it's just more convenient to slap a cone filter on then try to adapt it to the stock air intake system, which would probably be undersized at that point.

 

[BudAshes]

Bose is still worse

 

[7window]

I have k & n cone filter on one of my car before I sold it. The car had 200k on it. I don't know if K & N added more power to my car or not but I felt it did. I did not dyno my car for HP. The K & N did not damage my engine but it was the blown head gasket. The wierd thing about K & N is whenever i clean it, next to the filter, is always a pile of gritty dirt. Looks like sand. I never figure out why the dirt is always there next to the filter. Not on the filter, it is next to it. Whenever I clean the area it will reappear the next time I look.

I stopped using K & N because I got tired of taking it off for dmv inspection.

 

[AmdEmAll]

Noticed a good difference in my Lexus LS430.. on a civic id doubt you'd see any difference.

I see no oil gunking up.. and my Amsoil with 8k miles on it still looks new.

 

[ProchargeMe]

If you want MORE air for your engine to use, get a blower. Why do people think a filter and a tube will give them 100 horsepower?

 

[JCH13]

If you want MORE air for your engine to use, get a blower. Why do people think a filter and a tube will give them 100 horsepower?

Because stupid people.

 

[Pacfanweb]

If you want MORE air for your engine to use, get a blower. Why do people think a filter and a tube will give them 100 horsepower?

As mentioned before, stupid. Same reason they think mechanic in a can will fix everything.

What people fail to consider is this: The stock air filter will already flow more than the engine can use. A tube I can see, a more direct shot, or less restriction internally, but just a filter does nothing.

 

[Throckmorton]

As mentioned before, stupid. Same reason they think mechanic in a can will fix everything.

What people fail to consider is this: The stock air filter will already flow more than the engine can use. A tube I can see, a more direct shot, or less restriction internally, but just a filter does nothing.

Some stock air filters are too restrictive. My 4.6L Mustang has a smaller filter than an e36 BMW with a 2.8L. But K&N isn't necessarily less restrictive because of the fewer pleats, and to the extent that they are less restrictive it's by having bigger pores and filtering less.

 

[Gillbot]

Because stupid people.

Yep... LOL

Noticed a good difference in my Lexus LS430.. on a civic id doubt you'd see any difference.

I see no oil gunking up.. and my Amsoil with 8k miles on it still looks new.

No you didn't feel a difference.

As mentioned before, stupid. Same reason they think mechanic in a can will fix everything.

What people fail to consider is this: The stock air filter will already flow more than the engine can use. A tube I can see, a more direct shot, or less restriction internally, but just a filter does nothing.

Perhaps, but still, they aren't going to feel a difference. That's where I laugh the most. That is, unless their original filter was nearly clogged off when they changed it.

 

[JCH13]

Yep... LOL

No you didn't feel a difference.


Perhaps, but still, they aren't going to feel a difference. That's where I laugh the most. That is, unless their original filter was nearly clogged off when they changed it.

I think this is why many people think whatever upgrade part they installed is 'amazing,' because the part they're replacing is totally shot.

 

[AmdEmAll]

Yep... LOL

No you didn't feel a difference.


Perhaps, but still, they aren't going to feel a difference. That's where I laugh the most. That is, unless their original filter was nearly clogged off when they changed it.

Yes actually I did.. the car is much more responsive. Why is that so hard to understand.

 

[Jimzz]

Yes actually I did.. the car is much more responsive. Why is that so hard to understand.

Because its bullshit if you think a air filter change would make the much differance. Unless the last filter had a dead dog stuck in it.

 

[Greenman]

Yes actually I did.. the car is much more responsive. Why is that so hard to understand.

Because for the car to be more "responsive" it would have to be producing more horsepower, or the power curve would have to be peaking sooner. The air filter will only change that at wide open throttle near red line, unless the stock system was very poorly designed or plugged. It's possible that Lexus made a terrible mistake in the induction system and it was restricted to the point of starving the engine of air, but it's far more likely that your old filter needed service, or the K&N just makes more noise and sounds faster.

 

[BudAshes]

Yes actually I did.. the car is much more responsive. Why is that so hard to understand.

Does your Lexus have a Bose stereo?