In Reply to: K&N filter worth it?? posted by norman on September 19, 1999 at 20:18:43:
I installed just the drop in K&N filter and noticed immediate throttle response improvement and hwy MPG went up about .75. I only montiored it for one tank. It took the Motronic about fifty miles to adjust itself. I was relatively impressed with the changes. I have used K&N before on two stroke motorcyles and they can really make a big difference.
Most typical air filters made of paper must be of a denser nature to prevent abrasive particulates from penetrating them and entering into the engine. This density also reduces air flow and restricts the engines ability to respond.
K&N uses a cotton fiber weave in a pleated design that when properly oiled will stop all particles of significant damaging size. Remember it's the grit, sands and abrasives that help to degrade metal surfaces. Most organic particulates (pollens) are more of a nusiance as they will help to clog a filter but do relatively little harm to an engine with a operable oil filtration system.
As for the concerns of oil contamination, my information taught me that most quality brand oil filters will trap micro particulates that would be significant to cause any detrement to the engine. Provided it is changed frequently. I've also seen the results of the magnetic drain plugs and filter bands. They can really help with the break in of new or rebuilt engines and can dramtically clean up old neglected engines oil systems.
You stand a greater risk of damage by not changing the filter and oil every 3,000 miles, running the engine low on oil for extended periods, or using cheap brand products. And of course there's the excessive engine reving when first started (especially in cold climates). This can do considerable damage in the shortest time.
Most quality engine oils today contain more than sufficient detergents to eliminate any particulates, contaminants or 'dirt' to safely guard your engine.
[This is partly why so much oil is being recycled. The oil can be cleaned with solvents, micro filtered, supplemented with additional detergents and viscosity additives and then resold as low end low grade motor oils.
While recycling also protects the environment,it's also excellent P.R. for the oil companies and they can make easy money. It's an old trick of the oil industry. Of course as we all should suspect no company does something just to be 'nice' or 'Earth Friendly'. My father worked for Texaco for twenty years. I learned alot about the scams and truths.]
My experience with oil based filters is that they will actually provide greater protection but typically require more frequent cleaning.
The K&N design is unique and from those I know that use them they are quite happy. I can't say how the filter performs under severe or adverse conditions such as sand storms or off roading in Mexico but under typical driving conditions I believe they are more than sufficient and will dramatically increase air flow allowing the engine to optimize the mixture. I can not attest to time track results, horsepower boost or other high performance results. I use my car as my daily driver and in my circumstances of necessity the K&N was worth it.
If I change the typical air filter every 3,000-4000 miles (say with each with each oil change. As I believe is most beneficial to keep a standard paper filter providing the necessary air flow volumes.) then I easily outspend the cost of the K&N in one year.(Unless I buy the really cheap filters)
The K&N is a guarenteed product and if your unhappy with it they'll usually refund your money. Personally I'd try one out andd decide for my self. Check out some of the other E34 & BMW sites there's a considerable bit of talk out there on the K&N filters.
Hope this helps and Good Luck!
: the upgrade bug bites again. Do K&N filters improve performance? mileage? thanks