Air Filter Recommendations
 

I would like to know what you guys like using for your air filters. I always thought K&N was a good brand, but the guys at autozone told me this was not the case. I was somewhat doubtful of his response, but what do you use? I have a 2000 Boxster S.

I bought a Fram... from RockAuto Parts online... paid $12 on a closeout special.

Evo Hi Flo cone filter, lightly oiled.

Mahle
 

I use Mahle and think it's a good choice. I've bought K&N before for other vehicles and in my opinion they're an over priced scam.

2000 Boxster with K&N with no issues.

1999 Boxster with K&N with no problems.

I have used K&N filters on my Cars,Motorcycles and jetski's never any issues with them.

Porsche OEM paper filter.

I've had a BMC filter in there for the last 25k miles and I like it.

I would stay away from K & N if you plan to keep your car long term. The filter simply allows too much dirt into your engine in the long run.

Ended up getting OEM

I've never had a problem with K&N in any application I use. The myth of allowing to much dirt comes from suppliers of disposable paper filters not moving their products.

Since you decided on an OEM replaceable good luck, I was going to give you one of my K&N's. I have two but don't need them anymore because I installed a EVO.

i'll gladly step in and be a recipient of a 'free' K & N :cheers: i'm a noob but i'm a great guy and love K & N

While some have experienced K&N induced MAF problems, many have not. The theory is some folks over oil them. I don't like them for my Box, but have them on the 914.

I wouldn't put TOO much stock in what the flunky at Autozone says.

I would think that the OEM filter is fine, or go K&N. Unless you spend a lot of money and put on an afterarket intake - I can't imagine that the k&N stock replacement would make a difference that you would feel..

anyone here actually hear or feel a difference in performance after putting in a K&N stock replacment filter?

K&N has been around for a long time.

It was first used only by racers who wanted more air into their engines. The tradeoff was more dirt and grit simply because in simple terms, the holes are bigger - that's how it lets in more air.

Racers didn't care because their engines were constantly being rebuilt- price of admittance.

But, having pretty much saturated the racing market, K&N started hocking it to consumers for it's longevity, or re-usability, not it's performance.

It was marketed as the 'Million Mile Filter', replacing a few dozen Fram, Autolite or AC/Delco's a consumer would use over the same span of miles. The fact that it offered less protection (which is the opposite of what you want in a street car) was never mentioned, and since cars of the day rarely lasted more than 50k mi., excess wear never really showed up.

Fast forward and today many people use them seeking the performance benefits, disregarding the additional wear. Most of the dirt passed through one is silicate (read sand), and much of this works it's way into your oil, to be circulated around the engine.

There are no free lunches. Many experts have pointed to the K&N as a cause of early MAF failure and there's lots of anecdotal evidence too. If you want the performance of a K&N, be sure to use much less oil than called for when 'refreshing' it, and also consider shortening your oil change intervals as well.

:cheers:

This is a good question and probably timely for me. I priced a NAPA cabin filter and puked at what they came back with. So, for wise economy and effective performance, where do you point for air filters?

Was it the activated carbon filter? For a convertible that's an absolute waste of money unless you spend a lot of time with the top up, or use the hardtop. The plain paper filter works just as well filtering and is much cheaper. NAPA doesn't carry it, but the dealer does and it's MUCH cheaper.

Their air filters (NAPA) lists for $26.99, comparable to dealer price.

:cheers:

assuming the K&N does affect the engine by letting more dirt in - is there REALLY a gaint o be had by just dropping one in?

i changed to a K&N on a past car and did notice a gain - but that car was turbucharged, and intake/exhaust mods provide a bigger bang for the buck on forced induction cars....

on our cars - does a simply drop in replacemenet K&N filter add any power you could feel???

i had the K&N on my Racing Beat "cold air" intake for my heavily modified Miata. The intake was awesome for the money spent. Great sound and a marginal increase in power. Not bad. The problem was that whenever I removed the filter to clean it, the thing was just filthy. the sink in my garage was full of grit, sand and all manner of debris. I'm not really sure what it was filtering! large birds? great.... I have to think that much of that was making its way past the filter. :(
Not doing that with the Boxster I thought.

I use the the Mahle from PAP-Parts or Autohauz. I don't see a reason not to.

Perfectlap,

Did you read what you wrote? Let me quote you;"The problem was that whenever I removed the filter (K&N) to clean it, the thing was just filthy. the sink in my garage was full of grit, sand and all manner of debris." Then in the same breath,"I'm not really sure what it was filtering!"

Let me tell you what it was filtering...GRIT, SAND and ALL MATTER OF DEBRIS!!

Was your paper filter that dirty when you replaced it? No? Then you should ask yourself,"I'm not really sure what it was filtering!"

Air flowing through a tacky oil impregnated cotton media will catch more dirt than a dry paper filter. If the dirt is caught in the paper the draw of air can work it through. Once dirt is caught in oil its there to stay until the break down solution is used to clean the filter.

P.S. If you had that much crap in your filter you might want to check it more often.

I completely agree with Jaxonalden; I've been using K&N filters for years on my 911s and clean them at least once a year (more often with the track car).

My '73 is equipped with Weber 40 IDA triple throat carbs that have jets which are very sensitive to small dirt particles. I have not had a problem related to air filtering to date. My Box S with the cone gauze filter also has not caused any problems with filtering or MAF issues (but I sure love the sound!).

I use Mahle Air Filter SKU: W0133-1628932. Costs around $23 on line. Works fine for me.

I look at all of the air filters I buy (Chevy, Acura and Boxster..even my lawn mowers) and my filters stay clean for the most part. Maybe it because where I live and where I drive. No deserts, beach sand or dusty, dirt roads... all highway and suburbs. We have our fair share of rain which also keeps down the road dust.

Another consideration to make in your filter choice.

That doesn't make any sense, or at the least is an apples to oranges comparison. Sounds like it's straight from the K&N website.

An air filter is a balance (read compromise) between absolute protection and performance.

IIRC, the K&N filters down to 30 microns while the avg. paper filter filters to 8 microns - an almost 4:1 difference. K&N's afford marginally greater performance while paper filters seem to favor greater protection. Oddly for both, the more they filter, the better each filters, but performance lags off as this occurs. You clean and recharge the K&N and replace the paper filter.

Interesting that neither Porsche, or any other manufacturers that I know of offer K&N type filters. If the gains were so stupendous, you'd think they would, if even only as an option.

I'm not advocating either, use what you want. But realize that there is a definite trade-off and make your decision using this knowledge rather than the more than prolific hype surrounding K&N's.

:cheers:

My response came from one source and one source only, ME. You don’t have to be a stinking engineer or a rocket scientist to look at something and then let common sense tell you the answer. To tell you the truth if you want to improve a K&N’s filtration you would add extra layers of protection like a pre filter (Outerwear) over the filter. It s made of a fine mesh that will stop sand and other debris, off roaders use them religiously. I have one on my EVO filter.

You can also install an oil impregnated sponge type filter that also goes on over the K&N, all for the same reason of keeping the filter the last line of defense against dirt.

As far as the OEM using a K&N or any other type reusable air filter. It’s all about getting money out of the consumer. You think Porsche or any other manufacture wants to sell something that can be used over and over than something that’s disposable that the public will have to come back for and buy? Please.

I applaud companies, like K&N, for making something that makes sense, saves me money and improves performance. If it wasn’t for those kind of company’s we would all have to buy our parts from the OEM.

I'm not a spokesperson for K&N, I just believe in and love the product.

if I buy a K&N replacement filter, and go install it in my car today - then go for a drive, am I going to notice *anything* at all - sound, performance, ???

I didn't notice a bump in sound or hp when I installed my BMC which is just an expensive K&N. These filters only add maybe 2-3 hp so it's not enough to feel on its own. The main benefit of these cotton gauze style filters is that they are reusable and washable....a couple extra hp is just a bonus.

Honestly, you'll never feel any increase (if there is any) in HP from an air filter.

If you install something like the Evo Hi Flo (which I have), you will immediately notice an intoxicating howl every time you hit the throttle...worth the price of admission all day long!

Isn't that what's it's all about?

I would consider the EVO if it wasn't such a PITA to install and tearing apart the stock instake wasn't necessary.

Not really.... sometimes 'common sense' is just plain wrong. It was common sense that led people for millenia to believe the earth was flat and not round. ;)

Porsche could add a K&N as an option and markup the hell out of it, in fact, they'd not have to make a single change to the car to do it. Heck, you'd think K&N would just give them to Porsche so they could advertise that it was standard on Porsches.

Of course, I doubt that K&Ns have TUV approval, and that's a MUST for any car part being used in assembly in DE. Perhaps K&N never submitted it to TUV for approval, or perhaps it was not granted approval...for any one of a number of reasons.

Mann or Mahle make the replacement filters and at best, Porsche only gets a licensing fee for their logo on the box. But many people get them generically, not from a dealer - even NAPA sells them. Then, Porshe doesn't see a dime.

Agreed, K&N have a loyal, and dare I say, near-fanatical following. But, I've never seen convincing evidence of significant power increases, especially when weighed against the cost.

I have seen studies conducted under repeatable protocols comparing retail 'oiled gauze filters' to several name brand paper filters using a wind flow bench and injecting equal amounts of dirt/grit typical in size and makeup of dirt extracted from used filters. The 'oiled gauze filters' did initially flow more air (CFMs) than the paper filters, because the holes are bigger. But, the paper filters themselves flowed more CFMs than the engine would demand.

The interesting result was that the 'oiled gauze filters' passed more debris/CFM and larger sized debris/CFM than the paper filters. And, at only 25% of the simulated mileage, the 'oiled gauze filters' saw a greater reduction in CFMs than the paper filters and were passing fewer CFMs than the paper filters in service (testing) the same length of time, meaning that they were now underperforming the paper filters.

So it seems that in order to maintain any performance 'edge' you'd have to clean and refresh the oiled gauze filter' 4 times as often as replacing the paper filters. I was going to post the link for this test, but I see now it is dead. The test was performed using the SAE J726 protocol. Here is a link to a copy of the tests results: Debunking the K&N Myth - Why OEM is Better

Except for one post here praising the accoustic benefit of the K&N, which may be justification in it's own right for some, I haven't seen any benefit over the paper filter.

Initial cost is greater, maintenance is greater, performance gains are unsubstantiated, protection is less, and they are linked to issues with the MAF sensors on the Boxster (of course that could be mishandling, but not an issue at all with the paper filter).

I do think people like to showcase their K&N as noted by how many members list one as a mod on their signatures (it's only an air filter afterall, not at all noteworthy IMHO).

As I said, I'm not advocating any choice for anyone, nor am I condemning them for the choice they do make.

But facts, not hype, help people make informed decisions, then it's up to each individual to decide which to choose.

:cheers:

It's been stated and results have been posted, but I have to restate that K&N filters are total crap. For how poorly they (and similar products) function as a filter, they really don't offer any substantial advantage in any respect over factory.

$20 OEM filters every couple of years for me please.

The air filter controversy is the abortion issue of automotive BB's...

No... that would be Motor Oil... :)

:cheers:

I wasn't thinking with my dipstick JIMMMEYE

Every couple of years? :eek: You go girl!

Hey now, men drive Boxsters too... :D

Do you recommend some other air filter change interval? My particular car sees around 5,000 miles a year, so 10,000 miles changes seems reasonable.

Men do indeed drive Boxsters!

The recommended Air Filter change interval is at 40k mi. But, that assumes 'Ideal' conditions, which almost no one encounters.

Drive frequently on the freeway, dirt roads, past construction zones, desert, wet or humid climates, high rpms, and you need to shorten the service interval. How much shorter? Can't say, no interval has been established.

Personally, I'm comfortable pulling my paper filter every 10k mi. and blowing it out, from the reverse side, with compressed air. I replace every 20k mi.

:cheers:

Yep... I'd say my car falls under the 'severe' category. So, for $20, might as well. That and it was on the original filter when I picked it up last summer, so I feel bad. Only had 12k miles, but yeah... it was pretty shot.

It can be argued, but the K&N will not do the job of protection that a decent paper filter will in my opinion. Then there's the MAF issue from oil vapors to be concerned with. I don't want to pay extra to get less protection and increased risk.

I thank God I live in a country that gives me the freedom to pick my own air filter (at least for now :rolleyes: ).