Whats the truth about K&N typeair flters? Actually do anything tangible?

[Redsquall]

Is there really any horsepower increase, and if there was – why wouldnt they just put them on all new cars anyways?

[DMCMW Dave]

Is there really any horsepower increase, and if there was – why wouldnt they just put them on all new cars anyways?

1 - The benefit is arguable (and I'm sure there will be arguments). The let more air through (which is only of benefit at wide open throttle, and how often do you do that) and probably more dirt too.

2 - Because they require maintenance rather than being thrown away. And cost a lot more.

[Redsquall]

Makes sense to me. Thanks Dave!



1 - The benefit is arguable (and I'm sure there will be arguments). The let more air through (which is only of benefit at wide open throttle, and how often do you do that) and probably more dirt too.

2 - Because they require maintenance rather than being thrown away. And cost a lot more.

[Josh]

If they are not maintained properly they can cause a decent amount of trouble (over-oiling filter and coating your entire intake and all the sensors along the way with oil)

[PJ Grady Inc.]

A little side story concerning K&N filters dating back a tad before the DMC 12.

In 1979 I bought a brand new Suzuki GS 1000 motorcycle. It was my introduction to the world of loans and credit as I financed it. Not to digress too far one of the first things I did was look for ways to make it faster. I was motocrossing in the 250 expert class at the time and my need for speed was rather pronounced.

I ripped off the stock airbox (notoriously restrictive) and bolted up a bank of Mikuni 29mm "smoothbore" carburetor's and topped them off with K&N's. To address the exhaust egress part of the equation I finished up with a set of Kerker 4 into 1 headers. This gave me two things. More power for sure but also a serious case of jetting calculations that was way over my head at the time.

After extensive fiddling with little improvement in "rideability" I brought the bike over to a well known speed shop named "Orient Express" in Baldwin N.Y. as the owner was seriously into performance mods. He had a totally worked 1300 Kawasaki that was doing some major damage at the drag circuit at the time as in winning! I can't remember his name (Mike I think?) at the moment but the first thing he did was rip off my brand new K&N's and clamp up a set of Uni oiled foam filters saying the K&N's were restrictive in comparison to oiled foam filters. He told me what jets to install and after it was done the bike was much faster than stock. I just sold that bike two years ago and I sort of miss it but bikes and Long Island don't mix well. Don't ask me how I know as that's another story.

The lesson I learned was that K&N's are sort of stuck in the middle between paper and oiled foam filters with the disadvantages of both and the full benefits of neither. They are harder to effectively clean than oiled foam filters while offering marginal flow improvements over paper disposable filters. They are generally more expensive than both paper and foam as well.

If you want convienance and lower cost go for paper. That's why OEM's always use them. Can you see your wife or signiticant other actually cleaning an oiled foam or K&N filter? If you want the most performance combined with the best filtering oiled foam beats everything else. My motocross bikes would use 3 layer oiled foam filters that would flow clean unimpeded air while being caked with a 1/4 inch layer of the finest "Bridgehampton" sand that dusy track could kick up.

Some of you recognize the Bridgehampton road course as the place where John Delorean did his Legend turbo track testing. Sadly although I raced on the dirt track overlooking the road course in those days I was not part of the inner circle invited to the track test day at that time. We were an official DMC dealer but for whatever reason DMC company personnel did not see fit to invite the local dealers to that event.

That I truly regret....wow I really did get off the subject didn't I? Sorry about that but one thing always leads to another with me.

Rob Grady

[DMCMW Dave]

If they are not maintained properly they can cause a decent amount of trouble (over-oiling filter and coating your entire intake and all the sensors along the way with oil)

There are no intake tract sensors on a DeLorean, but on modern cars excessive oil will screw up the mass air flow sensors.

[DMC-81]

To each his own, but I swear by them. That's the first improvement that I make on a new/new to me car. Compared to stock filters, I find that the engine breathes better, with quicker rev up and rev down. Also, these are all the better when combined with a cold air intake. I put both on my other car, and aside from the benefits mentioned, I found a noticeable improvement in intake sound as well. I'd love to see a before and after on a dyno. It doesn't seem negligible to me.

I bought one for the DeLorean (K&N part #33-2726). I found DMC's price was competitive, so I got it there. Maybe these filters do more for a higher horsepower engine, but with 130 to 200 HP on a D, I think anything helps.

I have had some K&N's long enough to have to re-oil them, and it is not as bad as it sounds. Just spray the filter with a garden hose, let it dry, and spray the new oil on it. As mentioned, not too much.

I haven't tried the oiled foam filters, so I can't draw any comparison.

Why don't cars come with them from the factory? I think cost, and the minor maintenance of the filter. It's a performance upgrade.

[mluder]

I don't know... seems like a pretty good investment as the K&N filetr rarely needs to be cleaned. The manufacturer recommends approximately every 50,000 miles or when you can no longer see the screen material.
Tehy have pics on their website showing you how to tell if it's necessary.
http://www.knfilters.com/cleaning-pics.htm

Of course it all depending on where your driving your car.

Cheers
Steven

[DMC5180]

A little side story concerning K&N filters dating back a tad before the DMC 12.

In 1979 I bought a brand new Suzuki GS 1000 motorcycle. It was my introduction to the world of loans and credit as I financed it. Not to digress too far one of the first things I did was look for ways to make it faster. I was motocrossing in the 250 expert class at the time and my need for speed was rather pronounced.

I ripped off the stock airbox (notoriously restrictive) and bolted up a bank of Mikuni 29mm "smoothbore" carburetor's and topped them off with K&N's. To address the exhaust egress part of the equation I finished up with a set of Kerker 4 into 1 headers. This gave me two things. More power for sure but also a serious case of jetting calculations that was way over my head at the time.

After extensive fiddling with little improvement in "rideability" I brought the bike over to a well known speed shop named "Orient Express" in Baldwin N.Y. as the owner was seriously into performance mods. He had a totally worked 1300 Kawasaki that was doing some major damage at the drag circuit at the time as in winning! I can't remember his name (Mike I think?) at the moment but the first thing he did was rip off my brand new K&N's and clamp up a set of Uni oiled foam filters saying the K&N's were restrictive in comparison to oiled foam filters. He told me what jets to install and after it was done the bike was much faster than stock. I just sold that bike two years ago and I sort of miss it but bikes and Long Island don't mix well. Don't ask me how I know as that's another story.

The lesson I learned was that K&N's are sort of stuck in the middle between paper and oiled foam filters with the disadvantages of both and the full benefits of neither. They are harder to effectively clean than oiled foam filters while offering marginal flow improvements over paper disposable filters. They are generally more expensive than both paper and foam as well.

If you want convienance and lower cost go for paper. That's why OEM's always use them. Can you see your wife or signiticant other actually cleaning an oiled foam or K&N filter? If you want the most performance combined with the best filtering oiled foam beats everything else. My motocross bikes would use 3 layer oiled foam filters that would flow clean unimpeded air while being caked with a 1/4 inch layer of the finest "Bridgehampton" sand that dusy track could kick up.

Some of you recognize the Bridgehampton road course as the place where John Delorean did his Legend turbo track testing. Sadly although I raced on the dirt track overlooking the road course in those days I was not part of the inner circle invited to the track test day at that time. We were an official DMC dealer but for whatever reason DMC company personnel did not see fit to invite the local dealers to that event.

That I truly regret....wow I really did get off the subject didn't I? Sorry about that but one thing always leads to another with me.

Rob Grady

Rob,

I bought an oiled foam filter for the Delorean 20 years ago. It was made to order by Amsoil. I used it for 10 years until eventually switching to the blue K&N knock off sold by Hervey. I can't say I could tell any difference from one to the other.

[PJ Grady Inc.]

I don't think any of the filter media types are inherently restrictive so no you normally will not see any horsepower increase by switching filters. Any gains would come from opening up the surface areas or reducing any restrictions in the intake tract such as a larger less restricive airbox. Even this could only increase power if the factory design was holding back on needed air for the engine. The main advantage of better filters is just what you would expect....better filtering of wear causing contaminants from entering the engine.
i believe multilayer oiled foam filters are superior in that regard as most offroad racing vehicles use them for the worst possible dust or mud conditions. That being said nobody I know offroads their Delorean much so in that case paper medias are fine. Whatever floats your boat is fine with me!



Rob,

I bought an oiled foam filter for the Delorean 20 years ago. It was made to order by Amsoil. I used it for 10 years until eventually switching to the blue K&N knock off sold by Hervey. I can't say I could tell any difference from one to the other.