[jklamerus328xi]

I recently replaced my engine air filter with a K&N air filter. After the fact, a local BMW garage owner said I should immediately switch back to a normal filter because the K&N would let too many contaminants through and it would destroy the charcoal filter which can't ever be replaced. Anybody else make the switch? Is it advised? Should I switch back? Any advice from the forum would be appreciated.

[VNeBLOB42]

Originally Posted by jklamerus328xi

I recently replaced my engine air filter with a K&N air filter. After the fact, a local BMW garage owner said I should immediately switch back to a normal filter because the K&N would let too many contaminants through and it would destroy the charcoal filter which can't ever be replaced. Anybody else make the switch? Is it advised? Should I switch back? Any advice from the forum would be appreciated.

For shits and giggles i tried to look into this. for easy, i just looked up K&N website to see what the micron rating was. and then tried MAHLE one of the OEM Manufactures. didn't really find anything to compare. so not really sure if K&N is Bad, but all performance filters are similar. I would say keep it clean with oil as per the manufacture recommendations. you should be fine.

I my self just got this http://www.cp-e.com/products/bmw-135...-intake-system

appears to be similar material to the K&N


K&N
Part 33-2367 Product Specifications
Product Style: Unique Air Filters
Filter Material: Cotton Gauze
Flanges: None
Height: 1.125 in (29 mm)
Filter Re-Oiling Amount: 1.74 oz (51 ml)
Outside Length: 14 in (356 mm)
Outside Width: 11.125 in (283 mm)
Weight: 1.7 lb (0.8 kg)
Product Box Length: 11.06 in (281 mm)
Product Box Width: 2.34 in (60 mm)
Product Box Height: 15.06 in (383 mm)


The Importance of Oil
A K&N Air Filter is made of 4 to 6 layers of cotton gauze sandwiched between two epoxy-coated aluminum wire screens. The cotton is treated with a specially formulated grade of oil causing tackiness throughout the cotton’s microscopic strands. The nature of the cotton allows high volumes of airflow, and when combined with the tackiness of the oil creates a powerful filtering media that ensures engine protection. In contrast, most other media can not maintain the same balance of airflow and filtration throughout the filter's life without sacrificing one or the other. With a K&N Air Filter, there is no sacrifice.


i couldn't really find any comparison specs as in the density of microns.

here is one of the OEM websites. once again didn't find any comparisons between a MAHLE and K&N.

http://www.us.mahle.com/MAHLE_North_...s/Air-cleaners

[jklamerus328xi]

Thank you for the quick reply and for the research you did on this. I wasn't too worried but I just wanted to be sure.

[rgbimmer]

it doesn't really add any performance so I would play it safe with the stock filter.

[jklamerus328xi]

Is that charcoal filter replaceable?

[wobbles1]

Originally Posted by jklamerus328xi

Is that charcoal filter replaceable?

No its not replaceable. Unless you buy a new airbox

[ENINTY]

Originally Posted by rgbimmer

it doesn't really add any performance so I would play it safe with the stock filter.

I agree with this. I use to use K&N filters in all my vehicles. I never noticed any increase in performance nor increase in MPG. And the cleaning interval is about the same as most car manufacturers recommendations for filter replacements (about 50,000 miles). The issue I have is cleaning and re-oiling of the K&N filter. You can very easily over-oil the filter which can lead to damage of airflow sensors downstream of the filter. Or, you can under-oil it and not get the proper filtering performance it is intended to provide. Just droping in a new OEM paper filter every 50K or so is a lot easier IMO.

[jklamerus328xi]

Good call on that. I've already installed the K&N but it's only been driven around the block. I can take it out and get a refund. I may just do it…. Thanks for the advice.

[JuppiOne]

agree, K&N is a waste of money, IMO

[jklamerus328xi]

What do you all think about 31-10131 AFE Pro Dry Air Filter? Is that worth the money?

[Kevco]

Keep the K&N filter and remove the charcoal filter!!

[jklamerus328xi]

Kevco you're the first to say this. Why do you recommend that? Is it bad for the engine?

[ndog14]

Originally Posted by Kevco

Keep the K&N filter and remove the charcoal filter!!

This.

Properly maintain the K&N and you'll be fine.

Also get http://www.turnermotorsport.com/p-18...335i-328i.aspx

[ECSTuning]

Aftermarket filters, such as the K&N, will be fine in your car as long as you properly maintain the filter. I'd agree with ndog14 suggestion of picking up a set of the aFe Dynamic Air Scoops (I have them available HERE). They help to shovel cold air into the stock air box or create a "ram air" affect.

ECS Tuning

[cssnms]

Stick with the OEM filter since you get NO benefit by using a K&N or any other aftermarket filter. Most if not all let more dirt into your engine even if properly maintained.

Here is an indpendent test conducted on varous drop-in filters. You should read though this carefully.

http://moto.lexp.net/wiki/ISO_5011_D...er_Test_Report

[benzo23]

I just use OEM paper filters from the parts counter with the charcoal delete, i had K&N before and couldn't feel or hear a difference, so every oil change i just spend 20 bucks and put a new filter in...not a big deal.

[jklamerus328xi]

CSSNMS - Thanks for the link to the study on air filters. Excellent information!

[techwhiz]

Changing filters on a Turbo == Do Nothing....
A normally aspirated engine pulls air in and the flow can be obstructed by a poor flowing filter. A turbo on the other hand is not real affected be the charge is compressed and your intake is running positive pressure, that is no vacuum.

Run the stock filter. I ran K&N on all my other cars, not on my 335 because there is no gain.

[Chris@codemybimmer]

Originally Posted by cssnms

Stick with the OEM filter since you get NO benefit by using a K&N or any other aftermarket filter. Most if not all let more dirt into your engine even if properly maintained.

Here is an indpendent test conducted on varous drop-in filters. You should read though this carefully.

http://moto.lexp.net/wiki/ISO_5011_D...er_Test_Report

wow...after reading that im having some serious concerns for my k&n....
thanks for the info.

to anyone who knows anything about motors and intakes, does having a less restrictive filter do anything for naturally aspirated engines? i know less restrictive = more dust/dirt entering the system but can it be justified for something like throttle response or any other upsides?

i love my bmw too much to damage it and i know how much it can run me for repairs so any insight would be helpful.

thanks
i use k&n drop in filters for most of my cars some have been running for about 10 years now i have an audi a4 2003 k&n filter for that as well and i have been taking care of it, doing regular maintenance and stuff. my engines been running smooth no problems for that long so is it really a huge effect if dirt passes through into the engine? i also seafoam the a4 every year or so.

[gtabfknkdnme]

u guys can either follow a chart that anyone can construct. or u can follow the 1000s of testimonies from car enthusiasts. knowing how so many people are on this forum though, you guys will 'play it safe, and not PULL THE TRIGGER on a k&n'

[Route 16]

How about Spectre brand? Any reviews?

It's dry non-oiled. I plan to run a cone filter.

[mlifxs]

I did the K&N and charcoal delete on my 328i.

Could be placebo, but I did think my car felt a little stronger after the change. Again, could be wishful thinking

One thing, to this day, that is not placebo is the 1.5 hwy mpg improvement I now enjoy after the change.