Do you think that somehow the dust from the cars in front of you doesn't enter the stock intake? I think that the air in front of the car is the same as the air under the car.

 

I think my M2 definitely picks up more crud. But its not unmanageable.

 

K&N ask that you oil filter before use. What the real reason for this? Does it help with the filtration, protect the metal gauze from corrosion preserve the element or what?

 

To quote that " .Does it flow better? At very high airflow volumes, probably. BUT, our engines CAN'T flow that much air unless super-modified, so what is the point? " .. remember boosted engines are dependant on that flow for power . on an NA engine maybe this statement is true . to a point. I just took my engine apart .. and it was not dirty .. I've taken my intercooler piping out countless times and its been quite clean .

I have an apexi intake .

 

It is to help filtration afaik. They compare it to using a dry cloth or a wet cloth to pick up dirt. The wet cloth picks up more.

 

Mazda knew the cone filters were bad news. Whether or not it was the high underhood temperature causing airpump failure, it should be obvious that hotter air = lower power and shorter turbocharger and engine life. The OEM air filter collects outside air, not under-hood air. (Unfiltered dust is bad too, of course.) IMHO the OEM FD air intake system is very well designed.

 

I dont really understand the point of this thread. If you want a higher flowing filter, more particulate matter will get thru. Thats a fact.

I have never heard of an FD engine failure (or damage) due to using a K&N filter.

 

+1

 

The point of the thread is that the K&Ns let in more dirt. Some users of K&N other than you might care, and have an interest in minimizing this.

And to your second point, flow rate depends on both the porosity of the filter and the area of the filter. A large area filter with low porosity can flow as much as a smaller area filter with high porosity. So it is possible with different filter designs to have high flow without extra particulate.

Since the damage is diffuse, and over a long period of time, it would be difficult to assign to a specific cause without controlled testing. In other words, your statement would be true if K&Ns cause damage, and also if they don't cause damage. So no conclusion can be drawn from the fact that you haven't read any threads stating "My K&N destroyed my engine".

There have been many anecdotal statements from users on this forum that intakes using K&Ns are found to be "dusty" or "gritty". And several times, in different threads, I've read the suggestion to put a dab of grease on the inside of the intake, and test it after a couple of weeks. If you ran this experiment, and the grease was gritty, would you think your engine was going to last as long as it would otherwise?

 

OEM airbox with OEM paper filter and a modified cold air intake hole in the plastic garnish snorkel panel above the airbox (with the intercooler duct blocked off to be its own intake) is how I run mine.
Basically copies how the 99-2002 cars left the factory. Eliminates hot intercooler air feeding into the airbox, and both the airbox and intercooler get their own source of cold air separately from the front of the car, using all stock plastics, looks 100% stock.

 

These engine fail far sooner for various other reasons than what some extra dust particles are ever going to do.. Unless you turn your car into a Baja contender, it's not an issue. It's just a marketing ploy for different companies to get you to spend money on their products. If it were really proven to kill motors, (rotary or not), there wouldn't be a single aftermarket air filter available as no one would be buying them.

 

I agree with Mahjik. The carbon and suit from a rich mixture will be far more coarse and damaging than super fine sand.

 

Who in the marketplace is going to take the time to "prove" that extra dirt from a specific aftermarket filter, mounted in a specific aftermarket CAI or other non-stock location, kills motors?

 

No one is going to take the time to do that because it never happens.

Our motors die from two main causes: Worn out coolant seals, and broken apex seals. Tiny particulate matter ............. doesn't matter.

 

And the fact that our engines create and build up far larger and far coarser particulate matter all the time.

 

So I can dismiss the thought of dust possibly causing all or some of the wear on my rotor housings when I was stupidly using a k&n air filter with no filter oil?

 

That is a bit different. It probably contributed to any accelerated wear. But I bet you ended up with a failure elsewhere besides lan apex seal or housing getting sanded down too much.

 

Ya there was a engine failure from detonation but we were discussing whether all the wear/grooves in the rotor housings and loss of compression was from a water injector issue I had and not enough premix, or from ALS seals, and I've been wondering if it might also be from the air filter.

 

So, summarizing:

a) We all seem to agree that K&Ns let in more particulate.
b) So far at least, there is no viable option for aftermarket intakes that improves upon K&N and still fits into the same form factor.
c) Some are not concerned about extra particulate, and believe it is self-evident that extra particulate doesn't produce extra wear (quite a surprise to me, but hey, I'm an engineer, not an insurance salesman. The wonderful thing about this forum is that all opinions are equal.)
d) Some are concerned, and are seeking steps to get extra filtering. I've posted what I plan to do - buying the prefilters K&N sells for this purpose.

 

a) I agree K & N may let in more particulate.
b) There is no viable option (for me) on my particular car and it's current intake system.
c) Some are overly concerned about the suspected amount of extra particulate involved. And I believe it's self-evident that the engines fail and are rebuilt due to many factors. None of which have been directly attributed...or even likely attributed to the suspected differential amount of particulate allowed in by K & N's as opposed to any other filter.
d) I'll certainly consider a pre-filter, but not until I pull out my K & N again for routine cleaning and re-charging.
e) I'm not an engineer...hey, I've never even tried to drive a train. And as a goverment worker I'm even lower than insurance salemen. But I think my opinion is definitely equal with your's, and best for my car.

 

Filtration Testing for Amsoil, K&N, Napa, Jackson Racing, Baldwin, and Mazda air filters on a Miata

 

Just a simple question: Do you have any idea how much flow restriction the K&N pre-filters will add?

 

From the K&N site: "Red colored pre-cleaners are made from large, open cell foam that is oiled. They will stop 90% of the dirt, yet only add a 2% restriction to the airflow of the filter. "


It may not help stop finer particulate any better than the main K&N. So adding the pre-filter may only extend the time between cleanings as opposed to improving filtration. But, best I can think of for these cylinder style filters.

 

A recent experience of mine may shed some light on why the K&N replacement filters suck at filtering. I couldn't for the life of me get my air box to seal right. Had I not been looking for a problem, I wouldn't have found one. I did notice that there was a slight gap on the eyelet side of the box. I tried greasing it and all kinds of things to get it because it was so close. I never was able to get it right so I sent the filter back to K&N for a refund. It makes me wonder how many other people have that same gap and don't even know it.

 

My stock filter fit like a glove in the stock air box.