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Keeping it surreal
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The short version: The stock filter is much better.
 

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Keeping it surreal
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Dang, I hope not. The 325i I just bought today has a K&N on it. I would think if you took care of it properly you wouldn't have such issues. :dunno:
I`ll try to cut to the chase here....K&Ns admit *three* times the amount of dirt, plus the effed-up MAF issues, plus, they don`t do diddly squat for power or mileage....(you lose the cold-air-effect of the stock setup)
And did I mention that you can purchase FOUR stock filters for the price of one K&N....
(startin` to get the message yet ?)
 

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I tossed mine after only 2000 miles it needed a MAF sensor... it was supposed to go with the dinan stage one but I'll give up a couple of hp that I didn't notice anyway and not waste another sensor. I got the software more for the throttle response anyway, which is awesome IMHO compared to stock.
 

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Supporter of Bimmer Lore
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Just to add my $0.02

I've never been able to understand why people with experience in automotive technology and sound mechanical skills still come to believe an oily rag can do a better job than calibrated filter paper and a foam prefilter.
 

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Living Life At The Beach
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3,809 Posts
Before fuel injection and computer control K & N was relevant, as air filters had to be changed every 12,000 miles, and you could save money using a washable filter. Now they just contaminate your intake and cost too much. K & N has one heck of a marketing department.
 

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Anybody know if the CAI setup from Dinan uses an oiled filter or if I can run dry paper? This is one of my only hesitations on doing that upgrade. I forgot to mention before that it also ruined the mass air sensor in my 91 toyota v6 truck causing it to be a gross polluter ever since. After I swapped the newer motor in it, I'm running a stock box with a stock filter from now on...
 

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Before fuel injection and computer control K & N was relevant, as air filters had to be changed every 12,000 miles, and you could save money using a washable filter. Now they just contaminate your intake and cost too much. K & N has one heck of a marketing department.
+1. It worked great on my carburated '76 BMW motorcycle, especially as the excess oil would partially compensate for the declining octane content after the change to unleaded gas.

But I can't see any valid reason to use anything other than the OEM filter in a modern BMW - bike or car.

Tom
 

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Keeping it surreal
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Anybody know if the CAI setup from Dinan uses an oiled filter or if I can run dry paper? This is one of my only hesitations on doing that upgrade. I forgot to mention before that it also ruined the mass air sensor in my 91 toyota v6 truck causing it to be a gross polluter ever since. After I swapped the newer motor in it, I'm running a stock box with a stock filter from now on...
The stock setup *IS* a cold-air system that works more effectively than 99.9% of the aftermarket CAIs out there....
 

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catso
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If BMW engineers know enough to design a great car with a multitude of highly complicated inter-related systems, I think they would know enough to come up with a reasonable air filter assembly. Stick with stock.
 

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Keeping it surreal
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If BMW engineers know enough to design a great car with a multitude of highly complicated inter-related systems, I think they would know enought to come up with a reasonable air filter assembly. Stick with stock.
Correctomundo.....I would like to have the R&D money that BMW spent on the E46 intake system....I could retire comfortably on that....
 

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Well in short. they are good for performance. but not good for efficiency and longevity of your engine. the manufacturer would use such filter types if the car was being build for track because max air flow is always better for performance. however, the car you have was not designed for such application. the stock filter is the filter they choose based on lots of research and testing. they figured out through testing that the filter they choose to use was the best for the application it is being used for. you get the most fuel efficiency out of your engine. and the engine last longer. i don't care what any body says. a filter with higher flow also give you more dirt. and in some cases even though the filter is for performance applications when a car as sensitive as a bmw is using one it can actually hurt power because the car is simply not tuned for it. if you tune the car for it and modify the car in way that you need high air flow then sure go for it. but just a high flow filter by itself is making your car run in a manner the manufacturer didn't design it for. so life fuel economy and even performance can be reduced. however a dirty stock filter can also create similar problems. so use an oem filter, change it regularly. that is your best bet. i used to rebuild engines for Chrysler. what i have learned is. most anything you do cold air intakes high flow filters. pretty much any cheap performance bolt on you can get from advance or similar places. actually hurt power and ware your engine out faster. you want performance you need to build it from ground up around performance. taking an engine that was designed to do one thing, and then try to make it do something else is not a good thing to do.
 

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Better U.S made filters are available that are 100 times better at filtering dirt, have better air flow, look better, better built, no oil to screw MAF, and are cheaper! Still waiting for anybody on any forum to tell me what a Krap & Nasty has going for it, needless to say no replies yet. :dunno:
 

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Better U.S made filters are available that are 100 times better at filtering dirt, have better air flow, look better, better built, no oil to screw MAF, and are cheaper!
That's where I would have to differ. Be sure to thorougly inspect the box and contents of your U.S. labeled filter before plonking the cash at the counter: you might be in for a shock of discovering that the small print says "Made in China".

And yes, I agree yet again that K&N is worthless. Love the expanded name...
 
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