One of my co-workers showed me an article today on a K&N air filter test he found on the web. It was performed by a mechanical engineer who seems very reputable, and appears to not have any ties to a company, so it seems completely unbiased. The testing methodology seems to be solid as well.

What he found is a bit disturbing. I am no longer comfortable with my 2 K&N's in my Crossfire. I may go back to the stock paper elements.

It is a moderately long read, but very interesting. Here are some quotes:
"So what do these results mean? (referring to air flow testing for restriction) For one, there is very little pressure drop across any air filter, and the difference between the best (K&N) and worst (paper) is very small. Yes as total power output increases, air flow increases, and differential pressure would also increase. So a K&N probably does yield some power on higher output race motors where every last ounce of power must be squeezed out. On lower powered street cars, it is probably not much of an improvement over paper."

So that is what he discovered about the flow. Not too surprising. It is what I expected.

But here is the disturbing part:
"Did you see the dirty 2nd filter? Well that is the result of experiment #1. The test subject was the K&N air filter. Yes it let many particles pass through. The K&N was tested for 501 miles........Well there is a clear pattern on filtration ability compared to both flow and the type of filtration media used. The "high performance" cotton gauze and foam filters do not filter as well as some have claimed. I actually received an e-mail from K&N stating their filters filter within 99% of the OEM filters. This may be true, and 1% may not sound like much. I contend that 1% over many miles, may be important. Really, it is up to each individual to decide. The poorer flowing filters, remove more particles, and the better flowing filters remove less particles."

Here is the link so you can read it yourself. I bet this has gone around before, so I apologize if I am stirring up an old topic. All I am sure of is that I don't like the feeling that I may have added a few ponies at the expense of engine life.

http://www.bobistheoilguy.com/airfilter/airtest1.htm

 

Excellent article and excellent web site in general. I'm still sticking with my K&N's though.

 

I'm not an engineer but,it's clear to me that better flow would always let more dirt particles thru! Without even testing.K&N even states that. The recleaning of K&N filters done incorrectly would make them flow worse than new paper ones! I did price the Stock filters only at the dealer and they were the same price $30 ea. as the new K&N at AJUSA.com. But they're probably half that much at a parts store.

 

all the same info was posted when i had a k&n in my M3...i still ran with it...no problems.

 

I drive and drove K&Ns in every car. I never had any problems with the engines. I also will stay with K&N Filters.

 

Many people have smoked for years with no obvious harm. Then there are those whose bodies have assumed room temperture.

I'll stick with the stock filters.

 

I'll stick with my K&Ns. I have used them for many years on many vehicles and put them in my Explorer when I bought it in 1999. I now have 130k with no problems. I have never had problem one with any vehicles running K&Ns to include my MasterCraft Ski boat. I'll take my personal experience over some abstract tests any day. But each person has to go with what ever keeps them within their comfort factor. I happen to be extremely comfortable with my K&Ns.

 

Agreed, the K&N's stay for me too.

There is bound to be a loss of filtration with an increase of flow, could have told you that without tests

 

It will only really matter if you live in a dusty environment.

But who is really going to keep the car that long to really notice the difference. I am considering K&Ns when the stocks need to be replaced.

 

I checked with Bob Brady from Renntech and was told that the only concern about oiled filters is when the oil gets on the mass air flow sensor. You should make sure that there is not too much oil on the filter when it is first installed. Make sure before you first install the filter that you have god air flow. A good rule of thumb is to wipe some of the oil off of the filter. :mrgreen: He told me that it may not happen right away or it may never happen, but if it does you will have to replace the MAFS.

 

Since the crossfire engine is basically a Benz 3.2 liter engine, they will use the same Mass Airflow Sensor (MAS).

My experience with K&N in my C36 AMG, is that it breaks my MAS due to excessive oil in the filter when you purchase it.

In brief, the way the MAS works is that it has a needle that they put certain amount of electricity to heat it up to certain temperature. The amount of electricity will fluctuate due to the volume-changes of the air going into the intake.
When the oil from the filter sticks on the MAS needle, the heat tends on the needle to get isolated. So when you have more air coming in, it does not change the temperature of the needle. The ECU will raise a code.

So my recommendation would be either keep the paper filter (no oil) or use K&N, but try to reduce the oil on the filter.

 

11k + miles on mine w/no problems at all! Installed K&Ns @ 1k. Working very well for me. Don't over soak the filter when you clean it. Just enough oil to make it turn light red..... Not dark red..... Instructiuons are very clear. Been using them for years on virtuately everything I own with an engine w/no problems at all.

Again.... mine stay! :lol: :roll: :lol:

 

We are not trying to get anyone to stop using or consider not using the K&N filter, we just want people to be aware of what can happen if you do use them.

 

K&N Filters are about as valuable to any stock street vehicle as the various oil additives that have been marketed for the last 100 years. In short, air filters CAN NOT INCREASE HORSEPOWER.... At best they MAY allow the engine to develope closer to its actual hp (from 210 @ the crank to 212 MAYBE) but thats all. Save your money. Companies like this make a fortune based on junk science and pure B S. I always have a laugh when someone talks about their HP gains when changing air filters or putting additives in their oil pan. If you want to add cheap HP, add tuned headers and exhaust. Its the ONLY cheap H you can buy, everything else costs REAL money. All you have to do is go to the strip and change filters between runs, do it more then once each , and you'll save money to buy some real HP.

 

That's your opinion and you are welcome to it. I just happen to disagree. Where did you get your Crossfire painted to get "Red Pearl"? Any pictures?

 

I understand your need to "BELIEVE", but it isn't my opinion, its a fact supported by every single scientific study ever done on the effect of filtration on Four stroke engines. All out race cars run filters of various types in order to keep particles out, but would rather have none (ever look in the blower of a top fueler or funny car??) because ANYTHING that restricts airflow restricts the engines ability to reach its top HP. But you really should disabuse yourself of the idea that K&N or any other filter ADDS HP, because it isn't going to happen on this planet in this lifetime.

 

I don't know where you are getting your mis-information. But I'm not going to belabor this with you. I suggest that you stay away from K&N or other performance filters and I will stay with what I've used for years and know works.

I would like to know about your "Red Pearl" paint, though.

Have a great day.

 

I don't post misinformation, I've raced cars and built engines for 30 years. But you believe whatever you want, it won't change the laws of flow dynamics.
Its the stock color of the car, to quote the sticker "Blaze Red Chrystal Pearl Coat Paint".

 

I too have been racing and building race cars and engines for many years. I'm 53 now and started racing 1/4 migets when I was 6 in So. Cal. I also raced full midgets and prints @ ASCOT park in Gardena, Ca. (Now closed) from 1967 until I went into the Army in 1969. My open wheel racing career ended in 1972 after I wriecked my sprinter in York, Pa. and ended up in the hospital with a spinal compression injury. The Army gave me a choice to continue to fly or continue to race but that they would not allow me to do both. So I became a tuner and builder, on the side, and continued to fly helicopters in the Army. I have also gone tons of drag racing and now autocrossing..... Now you have my RESUME.. :roll: As if any of it matters. :roll: You have your opinion and I have mine.

What the filters do is allow the engine to get more unrestrictive air flow "over the stock" filter and provide the hp that is taken away with the more restrictive stock filters. If you want to argue with that you're not going to do it with me.

 

Thats really funny, you just repeated what I said. I raced dirt track in southern PA as well as drag raced. I'm older than you, I turned 57 last week. I don't have an agenda, I just smile when people say what you have said about something "WORKING" . I think you're smart enough to know that "oil additives" don't make horsepower and as you said neither do filters. If you like K&N filters and they cost the same, have at it, I only want people to know the truth.