KyKen

Anyone have any thoughts, experiences, or reviews of a K&N filter installed to the GLK250? Any improvements in performance or mpg due to lower air flow resistance as advertised?

http://www.knfilters.com/search/prod...px?prod=E-2998

super7pilot

This is a far more complex thing than one would think. Given that most engine bays are very limited on room. They (the aftermarket filter makers) necessarily have to build a filter of approximately the same size as the OEM filter. Therefore to increase air flow you will have to decrease the density of the filter material. The "only" way to increase air flow through the filter and maintain filter density to filter out very small dirty bits is to increase the surface area. Another minus as far as I'm concerned with K&N's (I have two K&N filters on the weber side draft IDF's in my Caterham) is that to filter properly K&N's need to be oiled often. I don't drive my Caterham a huge amount of miles maybe 200 miles a month & the filter oil goes away very quickly. I clean and re-oil every two months (max).

Now consider that most drivers have to be reminded by their cars to have the motor oil changed, Or that they almost never check their tire pressures either (hey I have run flats and TPM'S) so why bother. That does not bode well for a high maintenance air filter setup

It would be in the long run a bad thing for the longevity of our cars. On race cars that are rebuilt often longevity isn't an issue. Personally, I want my Bluetec diesel to last a very long time. So for me a few HP (maybe) isn't worth the long term risk to my engine.

Then there is the fact that even if I wanted my GLK to go fast & handle well. No amount of money could make a GLK go around a corner or be as fun as my Caterham.

Dominador

I've used aftermarket permanent filters in every vehicle I have owned. I've switched from K&N to AFE Dry filters since the oil can mess with newer car's air flow sensors. Not to mention cleaning the dry filter is extremely easy versus the oiled filter which must be washed and re-oiled. They both perform well and I wouldn't expect hardly any "performance" increase. Even if it got you 3-5hp you wouldn't likely notice. You may get improved gas mileage. I get them since for $50-75 you will never have to buy another filter. The standard filters add up over time.

GLKpaul

Whats your goal, more HP, less maint cost, better has mileage, all of the above? I'm a firm believer in each to his own, but for me saving maybe a couple of hundred bucks in filters by trying to clean a dirty filter back to clean with soaps, oils, washing, drying ... Just not worth it..

Considering the oem filter is perfectly designed for your car, then "more air flow" makes little diiference.

Myself if i was after more hp and wanting to "open it up" i'd look to exhaust , then cat delete next, and so on up to a tuner.

I've used k&n and others, in the end it was not worth the time, there are better ways to save some bucks, hp was not noticeable, and mpg not enough to think about.

My 2 pennies... Good luck let us know what you decide.. Let the debate begin...

KyKen

Thanks for the responses. I really appreciate the thought put into the content and the remarkable lack of BS found in other forums.

I should have been more specific short of being an advertisement for K&N. This is a direct-fit K&N air filter that says it will achieve all of the above desired improvements in performance without much problems. I am not trying to increase the horsepower to a racing performance level. But if a few extra horsepower come as a result, great. And no, I am not looking to put one of those orange K&N decals anywhere on the car. I have always thought of any internal combustion engine as a pump, so if I can reduce the intake flow resistance, I can improve the efficiency of the pump. With the Bluetec on the exhaust side, it's not worth the risk to even think of modifications.

I had used a direct OEM fit K&N for years on a supercharged competitor's model (over 300RW-Bhp) and I didn't have to put a cold air intake kit. I don't think they are practical for the amount they cost. This was for performance as the supercharger was flowing 140-160% of the design flow and I had a header-back exhaust flow system (gasoline). The downside was there was a risk of filter oil entrainment and contaminating the heater wire in the MAF Sensor since it was very close to the air filter box. I never had the problem.

Anyway, I hope this is a clearer request for any recommendations from anyone who has tried the direct-fit K&N on their GLK250. Has anyone experienced drawbacks such as a contaminated MAF sensor or any other DTC lean codes? And was there a noticable change in the drivability or performance of the vehicle?

I love the GLK so I don't want to mess it up. As an engineer, I just can't resist thinking of improvements even to a good thing!

KyKen

Thanks. I will take a look at the AFE Filter.

Update - of course, they don't make a direct fit (yet).

super7pilot

KyKen. An internal combustion engine is 100% an air pump. So the more air that flows the more fuel can be burned, Making more power. But the fly in the ointment is filtering the dirt from the intake air. The GLK engine bay is very crowded. But who knows, There could be a multi air filter set up. If not, That means a filter needs to be more porous to flow more air for a given size, Which gives dirt an easier route into the engine. That is why K&N relies on a bunch of sticky oil to hopefully catch the dirt on it's way through. Which means a lot of cleaning and re-oiling for a very minimal benefit.

Dominador

That's too bad. I got one for my 350, but it looks like they haven't ventured into the diesels yet. My only hesitance with K&N is the oil. That being said, the majority of issues with the oil come from over oiling when you clean it. Which I couldn't seem to control so I went with something easier to clean. However, I've also read that because dry filters don't rely on the oil they aren't as less restrictive as oiled filters.


There is mention of frequent cleaning of the K&N filter, but their website recommends 50K miles depending on conditions. I don't think I ever went that long without cleaning the filter when I had one. If you aren't driving in the Sahara or the back dirt roads of middle America I wouldn't think you'd have to clean it all that often. You're are far more likely to have damage to your vehicle from an accident in every day driving than I would suspect you would from your air filter choice.


In the end it is all personal preference. Everyone has their opinion and experiences. when it comes down to it just do what you want regardless of what people may think. You're the one that has to live with it.

fabbrisd1

No offense ... the K&N is "snake oil"..