Article listing K&N filters as the worst???

[Guelphguy]

Looks like a lot of actual Data proving K&N air filters to be the worst:

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm :(

[granit_silber]

As always its important to ask what type of filter is being tested and what is the implied usage of such. I assume that they tested the standard airbox type filter vs. a cold-air induction type filter (tube and cone configuration).
It does make sense that the K&N would both fail first and have one of the highest dust pass-through rates.
K&N filters are designed for high-flow applications. Most people I know running K&N (cold-air) are track guys and x-crossers that remove and clean the filter after each use, some even break down their engine after each race.

The other thing to remember is AC Delco is the GM house brand. So, of course it would perform best when placed into the vehicle it was designed for. Just like the BMW oil filter functions better than a puralator or wal-mart brand filter.

Racing filters are for racing applications and require more maintenance. K&N will also respond and say that most OEM standards for trapping of particles is 96% (which it meets)

Anyway, those are my thoughts, cool test.
-ashley


Looks like a lot of actual Data proving K&N air filters to be the worst:

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm :(

[632 Regal]

lets in oil from the filter itself and particles about 1/10th as big as a sand particle (the cone filters)

[bfd]

Neither Steve Dinan nor Jim Conforti recommend K&N filters either. Here's what these two *reputable* BMW tuners say about K&N filters:

Dinan's impression:
(by Keith Wollenberg: KKWol...@aol.com)

I .... talked to Steve Dinan about exactly this issue (the benefits of
adding a K&N air filter). He had two things to say:

1. The K&N filter is not as effective in taking particulates out as the
factory paper filter is, so you will increase engine wear.

2. The factory filter pulls cool air from outside the engine
compartment, while the K&N will pull warm air from the area behind the
radiator. Warm air is less dense than cold, so this can cost 6-13 HP!!

3. According to their actual tests on a Dynamometer, you will *lose*
horsepower, not gain it. He said he wished it were different, as lots
of people want to buy K&Ns from them, and he could make money selling
them, but they have a policy of only selling things which *improve*
performance.


Further, Jim Conforti of Bonnevillemotorwerks and "Jim C. chip" fame
states:

"This has been available for WELL over a year and when I got tired of
emailing personal copies, I put it on my website:

http://www.bonnevillemotorwerks.com/dynocharts/intake/KN/kntest.pdf


These are the ACTUAL TEST SHEETS from an ACTUAL FILTER LAB showing
exactly what was up.. not my interpretations, but SCIENCE. Testing done in an independent lab, by professionals, with no one trying to "get a conclusion" out of them. Testing, that had we the BMW community had to pay for, would have cost BEAUCOUP bucks!

(Luckily someone who works there is an all around nice guy and
BMW nut and got the lab guys to agree to a test as a "favor")

They show the passage of more dirt into the motor, and eventually
flow WORSE than paper filters.. I think that's simple enough."

[Craig]

K&N filters have been used on literally millions of cars with few negative consequences. Maybe they don't filter as well as paper filters, but it's not like you are getting boulders sucked into your engine with one on your car.

Also, that "hot underhood air" thing is at best a myth. Engine compartment temps are not much higher than ambient air temps once the car is moving. At a dyno or sitting at a stoplight they can warm up, but if the car is moving along the air in your engine compartment might be at most 5 degree warmer than the outside air, presuming you didn't stick the filter down under the exhaust or something.

My point is that if you like the K&N filter intake sound and are looking for something to clean up your engine compartment I don't think you'll do any real damage with one.

[casurfer911]

My point is that if you like the K&N filter intake sound and are looking for something to clean up your engine compartment I don't think you'll do any real damage with one.

Well does anyone know how to make a stock filter sound better without comprising the filter?

[Bill R.]

How do you know they have been used on millions of cars with few negative consequences? Fine particulate wear that takes place is over a long term not the short term... meaning most of these dorks that run K&N's don't keep the cars long enough for the effects to show up. That 100k mile car that blows a nice cloud of blue smoke on startup, he's a proud k&n owner no doubt.. Most of the performance enthusiast's running these will have plenty of other excuses why their engine went....The race cars that are using them are changing motors every race anyway so they could care less about longevity
I've seen first hand the results of these filters on an accelerated basis when used in offroad racers..
A few things to consider, an m30 at 3000 rpm has each piston travel 1693 feet per minute, meaning the rings are sliding over a quarter of a mile against a iron cylinder wall each minute...Oil is the only thing keeping them from rubbing metal on metal, now if you add some very fine dust to that oil , you create a polishing compound...(dust meaning ground up rocks)
At this speed of 1693 fpm you want the cleanest oil film you can get for these rings to slide on...Unless of course its a race engine and its getting rebuilt every race anyway... in which case you could care less about longevity..
Now the very same people who are very concerned about running synthetic oils should be concerned about running the best filters they can get with the highest filtration rate.. The best oil in the world won't help if you have abrasives in it...
Most of these owners on here now have purchased these cars at somewhere close to 100k miles.. and most of them did not have k&n filters on them when they got them...Do you think you would see so many good condition m20,m30,m50 and 60 motors if they had all been running K&n's their whole life.. I tend to think not.

As far as temperatures underhood...I think you should mount a remote temp sender under hood.. I think you'll be surprised how high it actually is.. You've got to remember that the only air coming into the engine compartment when your driving down the road is that which comes through the condensor and radiator..The radiator is a fairly good heat exchanger also.
Low cd front ends require that the grill openings for air be as small as possible and the fan clutchs regulate the amount of air that comes into the engine compartment going down the road, Instead of your 5 degree above ambient number I would hazard a guess that its much closer to 50 degrees above ambient. Minimum 200 degree radiator temp, fairly high efficiency heat transfer.. In the ac business a good heat exchanger will have only a 10 degree loss.. meaning that a 200 degree condensor will have 190 degree air coming out of it...













K&N filters have been used on literally millions of cars with few negative consequences. Maybe they don't filter as well as paper filters, but it's not like you are getting boulders sucked into your engine with one on your car.

Also, that "hot underhood air" thing is at best a myth. Engine compartment temps are not much higher than ambient air temps once the car is moving. At a dyno or sitting at a stoplight they can warm up, but if the car is moving along the air in your engine compartment might be at most 5 degree warmer than the outside air, presuming you didn't stick the filter down under the exhaust or something.

My point is that if you like the K&N filter intake sound and are looking for something to clean up your engine compartment I don't think you'll do any real damage with one.

[Craig]

How do you know they have been used on millions of cars with few negative consequences? Fine particulate wear that takes place is over a long term not the short term... meaning most of these dorks that run K&N's don't keep the cars long enough for the effects to show up. That 100k mile car that blows a nice cloud of blue smoke on startup, he's a proud k&n owner no doubt.. Most of the performance enthusiast's running these will have plenty of other excuses why their engine went....The race cars that are using them are changing motors every race anyway so they could care less about longevity
I've seen first hand the results of these filters on an accelerated basis when used in offroad racers..


Could be, but my point was more that there are more damaging things to worry about.



A few things to consider, an m30 at 3000 rpm has each piston travel 1693 feet per minute, meaning the rings are sliding over a quarter of a mile against a iron cylinder wall each minute...Oil is the only thing keeping them from rubbing metal on metal, now if you add some very fine dust to that oil , you create a polishing compound...(dust meaning ground up rocks)
At this speed of 1693 fpm you want the cleanest oil film you can get for these rings to slide on...Unless of course its a race engine and its getting rebuilt every race anyway... in which case you could care less about longevity..
Now the very same people who are very concerned about running synthetic oils should be concerned about running the best filters they can get with the highest filtration rate.. The best oil in the world won't help if you have abrasives in it...
Most of these owners on here now have purchased these cars at somewhere close to 100k miles.. and most of them did not have k&n filters on them when they got them...Do you think you would see so many good condition m20,m30,m50 and 60 motors if they had all been running K&n's their whole life.. I tend to think not.


Hard to say, as you said it's not easily tested either way.




As far as temperatures underhood...I think you should mount a remote temp sender under hood.. I think you'll be surprised how high it actually is.. You've got to remember that the only air coming into the engine compartment when your driving down the road is that which comes through the condensor and radiator..The radiator is a fairly good heat exchanger also.


Done, and it's a few degrees above ambient at most. Certainly not enough to cause any measurable power loss.



Low cd front ends require that the grill openings for air be as small as possible and the fan clutchs regulate the amount of air that comes into the engine compartment going down the road, Instead of your 5 degree above ambient number I would hazard a guess that its much closer to 50 degrees above ambient. Minimum 200 degree radiator temp, fairly high efficiency heat transfer.. In the ac business a good heat exchanger will have only a 10 degree loss.. meaning that a 200 degree condensor will have 190 degree air coming out of it...

The air is sucked from behind the headlights, not the radiator. The air behind the radiator is warmer, sure, but that's not where it comes from.

[bahnstormer]

more air = bigger holes = more dirt
its simple.

[Mitch90535im]

Bill, don't you know it's all about the sound? (lol) Oh, and the looks too, don't forget the looks...

[Craig]

Yup, I'm not disputing the numbers.

[632 Regal]

going directly into the K & N? The stock system sucks that cold air not some filter hanging out behind the radiator.

The only benefit of the K & N besides your "clean" look is the intake sound.

Reminds me of when I was young and everyone would flip their air cleaner covers upside down to get that BAUUUUUUUUU sound but even then all the air went through the stock filter.

No one is telling you not to do it, as a matter of fact I think you should do it to your car and see if you can measure a 60-80 mph difference from the stock setup.

[tim]

When you guys talk about K&N filters, are you talking about the cone filters exclusively, or the OEM replacement one that fits in the standard box as well?

PS.
(ot)
Jeff, lets see a pic of those mudflaps, or a link to a previously posted one cause I haven't seen 'em yet.

[Bill R.]

hot air that they are talking about is from the cone type... The factory airbox does a good job of avoiding sucking in engine heat.






When you guys talk about K&N filters, are you talking about the cone filters exclusively, or the OEM replacement one that fits in the standard box as well?

PS.
(ot)
Jeff, lets see a pic of those mudflaps, or a link to a previously posted one cause I haven't seen 'em yet.

[Craig]

going directly into the K & N? The stock system sucks that cold air not some filter hanging out behind the radiator.

The only benefit of the K & N besides your "clean" look is the intake sound.



Any kit for E28/E34 535i cars has the filter behind the headlights on the passenger's side of the engine bay. That's right where the cool air comes in. I've never seen one that puts it behind the radiator.



No one is telling you not to do it, as a matter of fact I think you should do it to your car and see if you can measure a 60-80 mph difference from the stock setup.

Well, it's hard to tell the difference with the turbo there. :p

[Guelphguy]

I have always used K&N filters and I must admit, this ad got me thinking? I just got this 535i and one of the first things I did was get a K&N....just the kind that drops into the stock box...I have been looking at all kinds of articles and well, It seems that even K&N admit that their filters only filter 99% of what the stock filter would...how much that 1% matters...well I don't know, I assume that anything sucked into the oil will also get filtered out by your oil filter as well....I only put about 17,000km a year on the car, so will I ever see blue smoke as a result of a K&N....????? Dunno?

[Guelphguy]

Just to quickly ad, I assume that a lot of conditions also play into this eg: if you drive on gravel roads....live in dusty areas...only drive on highways....how much dirt is the filter actually exposed to?

[winfred]

when i got my 535 the filter was just clamped to the boot on the afm hanging over the exhaust, it was probably killing 20 hp, i extended the filter to behind the headlight and added a homemade shield, i need to insulate the tube, how much if anything it adds i don't know, i do know that this is the fastest 535i i've driven :D
http://members.cox.net/wdixon27/535%20r%20motor


Any kit for E28/E34 535i cars has the filter behind the headlights on the passenger's side of the engine bay. That's right where the cool air comes in. I've never seen one that puts it behind the radiator.



Well, it's hard to tell the difference with the turbo there. :p

[Bill R.]

cylinders... it doesnt even get filtered by the oil filter until it passes through the rings and down into the crankcase. The damage is already done






I have always used K&N filters and I must admit, this ad got me thinking? I just got this 535i and one of the first things I did was get a K&N....just the kind that drops into the stock box...I have been looking at all kinds of articles and well, It seems that even K&N admit that their filters only filter 99% of what the stock filter would...how much that 1% matters...well I don't know, I assume that anything sucked into the oil will also get filtered out by your oil filter as well....I only put about 17,000km a year on the car, so will I ever see blue smoke as a result of a K&N....????? Dunno?