Air Filter Recommendations

[jmatta]

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!).

[r9i8c7k]

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

[vath2001]

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.

[Lil bastard]

Originally Posted by Jaxonalden

...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...

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.

[Jaxonalden]

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.

[23109VC]

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, ???

[Adam]

Originally Posted by 23109VC

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.

[jmatta]

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?

[Adam]

Originally Posted by jmatta

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.

[Lil bastard]

Originally Posted by Jaxonalden

...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...

...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...

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.

[Samson]

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.

[eightsandaces]

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

[Lil bastard]

Originally Posted by eightsandaces

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

No... that would be Motor Oil...

[eightsandaces]

Originally Posted by Lil bastard

No... that would be Motor Oil...

I wasn't thinking with my dipstick JIMMMEYE

[Jaxonalden]

Originally Posted by Samson

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

Every couple of years? You go girl!

[Samson]

Originally Posted by Jaxonalden

Every couple of years? You go girl!

Hey now, men drive Boxsters too...

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.

[Lil bastard]

Originally Posted by Samson

Hey now, men drive Boxsters too...

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.

[Samson]

Originally Posted by Lil bastard

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

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.

[Bobiam]

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.

[Jaxonalden]

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