K&N Filters

BLK87S4 · BLK87S4's Garage

I just had an interesting discussion with my local parts fellow about K&N filters. He told me I shouldn't use on on my 928 because the filter oil can goof up the MAF sensor's hot wire. News to me. Both of mine have had K&N filters but I try not to over oil. Anyone else ever heard of this?

Just curious.

SeanR · 07-12-2008, 06:37 PM

Yea, don't use them. Simple.

Much discussion about this on R-list, won't rehash it. Opinions vary but I've got 2 here that came on the cars that will never be used by me. Rog has 7 of them and can't give them away.

I suppose that if used by someone responsible, they might be ok, but why chance it?

N2O-SHARK · 07-12-2008, 07:10 PM

With little to no gains in HP, you only gain a cost benefit from the K&N's lasting longer. That said it cost more to replace the MAF than a few air filters. If oiled correctly any risidual oil that should get on the MAF wire would be burnt off in the hot cycle. But why take chances... I have the K&N on mine, however they are both K-jet so it's a non issue.

Danglerb · 07-12-2008, 11:22 PM

Anybody ever pull the U under the throttle and NOT find a pool of oil?

Most shops throw away the K&N every time they see one after "educating" the owner, so I have been tempted to try one on my early non MAF car, but bottom line I don't think there are any gains to be found in replacing the paper air filter.

N2O-SHARK · 07-13-2008, 01:35 AM

K&N filters have been scientifically proven to add up to 15% more HP and fuel economy. I've seen the commercials. PLus it's made in Germany and we all know the Germans make great stuff...no wait that's ShamWOW. That's right, I've replaced my K&N filter with a ShamWOW, no more oil on the MAF wire, it works like a whole roll of paper filters...It practically sells itself.

rjm65 · 07-13-2008, 07:15 AM

My daily driver is a '94 Ford Ranger with 230,000 miles. The last time I bought an air filter for it was in 1995 when I replaced the paper element with a K&N. I did have to replace the MAF back in '99 but I suspect that was just the MAF going bad and had nothing to do with the K&N.

My '79 928 has a K&N, it was on the car when I bought the car earlier this year. It will stay on the car. The 928 air filters aren't cheap, so having this one component be reusable makes common sense. Although I will say most 928's don't get driven in conditions that truly warrant an air filter change as often as most owners probably perform them.

Has there actually been a known case where a brand new out of the box K&N ruined an MAF, or have all the failures been after the first air filter washing? If someone over-oils their K&N and it ruins the MAF, can't really blame the K&N.

Danglerb · 07-13-2008, 10:21 AM

Rebuilt MAF is like $400, paper filter is $32. The failure mode of a MAF is typically a slow shift in accuracy related to the burn off cycle where about every 5 times the car is shut off the wire is heated to burn off contaminants. I suspect the basic heat cycle has some wear and tear, but the presence of anything on the wire has to make it worse. So its not like you would put on a K&N and the car dies, more like the accuracy shifts beyond the 3% the brain can correct for in 3 years instead of 6 years.

I am also not that convinced that K&N actually filters as well as a paper filter.

For $32 I don't have to think about.

m21sniper · 07-13-2008, 10:52 AM

K&N = junk.

Mule · 07-13-2008, 12:56 PM

My 87 S4 has had one for about 4 years now so my maf must be about to go off like a hand grenade. Virtually every race car on the planet has one. Find a modified turbo that doesn't have one. Ask Dave Roberts. His "Blackbird" uses 2. Over oiling will foul & eventually burn up the maf. Don't over oil. They flow more air & filter better than paper filter period. Oh yeah, you can feel the difference driving off.

Mule · 07-13-2008, 12:59 PM

Quote:

Originally Posted by Danglerb

Anybody ever pull the U under the throttle and NOT find a pool of oil?

Most shops throw away the K&N every time they see one after "educating" the owner, so I have been tempted to try one on my early non MAF car, but bottom line I don't think there are any gains to be found in replacing the paper air filter.

No shop has ever thrown away my K&N. If they do, they'll be buying me another one.

Danglerb · 07-13-2008, 02:37 PM

Whats really funny, this thread is pulling up a K&N banner ad at the bottom of the page.

K&N pays winning racers to use them, and specifically in racing they have ZERO benefit since anybody sane would be using a new paper filter, not an old clogged one, and new paper filters flow the same or better than K&N.

N2O-SHARK · 07-13-2008, 02:56 PM

My car uses a Hepa filter, helps with my alergies.

The K&N debate will never be won by either side. I have noticed, most, not all, of the K&N supporters tend to be K-jet guys where it wouldn't hurt. I think over oiling is operator error. Also like BoneDangler said, who hasn't seen a bit of oil in the bottom of the intake plenum? It's venting air from the oil seperator. Granted it's after the MAF and would have to back track against airflow but I guess it could happen. Doesn't the MAF have a burn off cycle to get rid of contaminents including oil?

rhjames · rhjames's Garage

K&N on my K-Jet----no issues.

it's old, reliable, and doesn't have a bunch of electronics to drive me crazy with-

just start/run it occasionally, put some Lucas fuel injection additive in (every tank fill up) and my own CIS mods-----no problems.

--Russ

rjm65 · 07-13-2008, 03:52 PM

I've never bought into the "filtercharger" K&N sales pitch, or that it straightens the airflow.... I just like the idea that I have a vehicle that I bought one air filter for back in 1995 and I'm still using it. I live in San Diego so I rarely have to clean it, it's not like it sees daily use as a farm vehicle. Most people that have a K&N probably overclean them and over-oil them and therein lies the problem. As it is most people probably replace paper air filters more often than they need to.

Yeah, pretty funny DanglerB... the banner says "None have ever damaged a Mass Air Sensor!" What's really interesting is that when you click on the link it takes you to a statement by K&N about MAF sensor concerns.....

http://www.knfilters.com/MAF/massair.htm

MarkRobinson · 07-14-2008, 06:25 AM

I've had a few K&N's in the past: if you over-oil them (dripping oil), it *could* happen, though the 928's MAF wire burn-off cycle would remediate this I'd think.

Still, dont use it: no HP benefit on the 928 and your oil will get dirtier much faster with a K&N installed over a normal filter.

Mark.

m21sniper · 07-14-2008, 06:35 AM

Quote:

Originally Posted by Mule

My 87 S4 has had one for about 4 years now so my maf must be about to go off like a hand grenade. Virtually every race car on the planet has one. Find a modified turbo that doesn't have one. Ask Dave Roberts. His "Blackbird" uses 2. Over oiling will foul & eventually burn up the maf. Don't over oil. They flow more air & filter better than paper filter period. Oh yeah, you can feel the difference driving off.

The cones aren't bad, it's the 'filtercharger' oem replacements that i'm talking about.

They are proven to allow more foriegn debris into the motor than a stock filter. If you oil them sufficiently so that it's filtration matches that of an OEM filter, it doesn't flow as well, and it runs the risk of ruining your heated MAF wire.

This comes from none other than Wally Plumley (from his old writings on other forums), one of the top 928 experts on earth.

rjm65 · 07-14-2008, 07:22 AM

Quote:

Originally Posted by MarkRobinson

Still, dont use it: no HP benefit on the 928 and your oil will get dirtier much faster with a K&N installed over a normal filter.

Mark.

Are you referring to the motor oil? Did you run some side by side oil analysis to compare the paper to cotton elements?

My real world experience is that I'm at 230K miles on my daily driver that has had a K&N for 225K of those miles. The main benefit I see is that I haven't had to buy an air filter for this vehicle since 1995. The recharge kits are about $15 and I can get 3 washings/reoilings out of them.

I've also used them on the dirt bikes I've had because the K&N's work much better than the flimsy stock oiled foam filters.

I've been happy with my use of a K&N. If it was a crappy filter I don't think I could've gone as far as I've gone (and still going) on my daily driver.

MarkRobinson · 07-14-2008, 07:27 AM

Yes, K&N's work: more so on some applications than on others.

However, I'd rather spend $ on replacing (vacuuming out my stock filters works for a few times) my factory filters than see black oil every 3-4k miles because my K&N's letting in too much dirt.

I see a noticable difference in oil color on my 911 turbo between the k&N & the OEM Mahle paper filter. Noticeable. That might be somewhat irrelevant, but still, peace of mind to know the factory pulls more dirt/dust.

Mark

Danglerb · 07-14-2008, 10:24 AM

Filters, oil, maybe real important, maybe not. I just buy what I need to not worry about it.

Mule · 07-14-2008, 12:35 PM

Quote:

Originally Posted by MarkRobinson

Yes, K&N's work: more so on some applications than on others.

However, I'd rather spend $ on replacing (vacuuming out my stock filters works for a few times) my factory filters than see black oil every 3-4k miles because my K&N's letting in too much dirt.

I see a noticable difference in oil color on my 911 turbo between the k&N & the OEM Mahle paper filter. Noticeable. That might be somewhat irrelevant, but still, peace of mind to know the factory pulls more dirt/dust.

Mark

So you think oil gets black from dust getting past the rings? Really? Come on. You might want to check that restrictor on the turbo oil inlet.