OT: K&N and debunking snake oil claims

[BlueSkyJaunte]

Folks,

I have an acquaintence who wants to buy a K&N filter for his vehicle--I've already explained the whole surface area vs. porosity issue that makes K&N filters look like snake oil to us engineers. However, I'm unable to find ACTUAL DOCUMENTED proof (one way or the other) of K&N performance claims (or lack thereof).

Does anyone know of any sites out there that have data from independent dyno tests and/or filtration performance tests? My google searches have turned up a lot of anecdotal evidence but no real proof.

Thanks.

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blue
'81 SC Targa

[Early_S_Man]

blue,

You didn't say what model car your friend has, but Bruce Anderson has made one point, repeatedly over the years in his column, and in his books ... both CIS and DME 911 engines suffer from restrictions and lack of tuning on the EXHAUST side of the engine, NOT THE INTAKE!!!

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[Jim T]

K&N published data showing that the stock paper filter filters out 98% of particulates in some standard SAE test. K&N's own claim is that their filter filters out 97% in that same test. That means stock lets in 2%, k&N 3%, isn't that a 33% increase in particulates?

Those numbers were on K&N's web site, and were also in an e-mail that K&N sent in response to an inquiry.

Bruce Anderson has written on a couple of occasions that I've seen that in his and Jerry Woods testing of K&N on SCs and 80's Carreras, there was no gain. In fact, there is no gain on those cars if you run no filter at all. Gee, Porsche has real geniuses, they didn't choke the engine with an air filter! Surprise.

Jim Conforti is the BMW tuner who is the BMW equivalent of Anderson. He had a tech session last year where they put BMWs on dynos and tested filters. There was zero improvement with K&N. That was reported in the BMW Club magazine Roundel in the past 2 years.

In European Car, in the past few months, they reported on a MB C320 that was modified by a German tuner, bored out, etc. to put out 150 more hp than stock. The use the stock paper air filter and filter box. Because in their dyno testing, the stock set up provides the stock engine with more air than the engine can process. Not only that, the stock system also provides the highly pumped up engine with more air than it can use. Of course, if the stock filter can provide the engine with more air than it can process, changing the filter to another brand (or leaving it out entirely) will have ZERO effect on power.

All that being said, I've come to the conclusion that MARKETING is actually much more appealing and stronger than science in selling products and building a name for a product. Actually, marketing combined with JUNK SCIENCE is almost unbeatable. Which is why I don't even bother trying to talk people out of K&N, Slick 50, (Cool Collar??), etc. etc. anymore.

[Hatari]

I don't know of any sites with hard data, but I can tell you that my 2.7 with Webers, Solex cams, and headers runs noticeably stronger in the upper RPM zone with the 6 individual K&N filters fitted over modified ram tubes (one for each choke). That is in contrast to a stock airbox with OEM element.

I only run the inidvidual filters occasionally as I do prefer the vintage stock cosmetics. The power difference is real, however.

Jack McAllister

[lsolon]

So, on a 72 911T, Should I run The paper filter, or the K&N which is in there now?

[BlueSkyJaunte]

Warren,

My friend drives a Dodge Ram (which is why this is wayyyy OT). I don't know about the intake vs. exhaust restriction on that V8 (5.6 L?). However BA's statements should provide a good data point for my argument.

Hatari, I wonder whether the power difference is a result of the stock airbox restriction as opposed to the change in filter elements. A real test, I imagine, would be the 6 K&N filters vs 6 paper cones (if such things exist), or the stock box with an OEM filter and a K&N drop-in filter. Of course we can't answer the particle question without some other type of test procedure.

Obviously I'm not going to believe any claims made by the manufacturer (nor should anyone else!). Perhaps Consumer Reports would like to take this on as a project?

Out here in AZ (just watched a dust storm sweep over the city last week) I'm all about as much filtration as possible--and screw the HP losses. The amount of grit on my car just from parking in the lot at work for 10 hours is enough to convince me of that! Anyone have two inline filters?

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blue
'81 SC Targa

[carnut169]

I have a K & N air filter on my car... never noticed a difference, but the advantage for me is that I don't have to buy new filters! Throw the K & N in the dishwasher, oil it up, and you are good to go again. I think that justifies the price of the filter even in dusty areas (just wash it more). Also, it would seem to make sense that the paper filters would become less and less effective and that would rob you of some performance. I would love to see someone do the dyno tests w/ the dirty paper filter vs. the K & N w/ same mileage. My 2c.

[iustasail]

Look at a track cars with Carbs or MFI; no air filters! Some have chunk stoppers or plates but they are so highly tuned that it makes a difference and when you are spanking an engine hard a lot of other stuff will crap out first from heat/revs vs. particulate mater in the air that filters give you nothing!

For a street engine that is tuned so much lower than a race motor; aftermarket air filters offer no tangible performance gains at a cost of inferior filtration;

High compression, hot cam, headers, carbs or MFI, velocity stacks, and high revs will benefit from less restrictive intake filtration than factory; which was designed to mitigate noise as well as provide filtration, in essence its an intake muffler to! Its back to the air pump theory and where the chokepoint is.

[movin]

WOW! Here we go again. Someone already mentioned the quantifiable benifit, improved intake track configuration which enhances intake air flow when using the adapter that that fits between the K&N filter and the air-flow sensor. The stock box is a compromise and in terms of promoting increased air flow in some cases inferior to the adapters available. Check PowerHaus' info. on this subject. They've done the dyno work. I ran K&Ns in my Honda MC, as does quite a few other motorcylists. To them running a paper filter is laughable.

[This message has been edited by movin (edited 08-08-2001).]

[Doug Zielke]

I have a few m/c's and don't run K&N's in any of them. They just pass too much dirt.
The only "laughing" I hear, is the parts guy who has rung up another sale...replacements for another set of worn out pistons and cylinders...ch-ching!

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'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
The Blue Bomber's Website

[Pillow]

If we are concerned with the best air filtration then lets retrofit our 911s with VW oil bath air cleaners. The absolute best way to ensure no crud gets in our engines.

I do not care about air filter added HP, becasue there is none. BUT it is cheaper in the long run to use a K&N filter as opposed to buying multiple paper filters.

Anything that is X microns thick that goes through the filter will get burned and passed anyway. I have no concern for 2% versus 3% filteration differences. I think the question is moot.



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Adrian Pillow
1979 911 SC
1966 VW Microbus
PCA - Peachstate Region

[JimS]

On a related note. It was stated that 911s are restricted on the exhaust side. I was wondering why then most of the 911 cams are ground with a significantly short duration on the exhaust lobe?

[Rod Walter]

JimS, perhaps someone else with more technical knowledge will jump in, but it makes sense to me that if the exhaust system can handle only a given volume then increasing the cam duration would result in excessive back pressure. I suppose that Porsche matched the duration with the scavenging abilities of the exhaust given the constraints of emissions control, sound regulations in various countries, and the peculiar needs of heat exchangers in cars with air-cooled engines.

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Rod Walter
'88 911 coupe

[Ted Stringer]

I don't know about the 911, but I have a K&N in my 93 F150 with a 351w. Made it feel like a whole diferent engine when in the higher revs, and it pulls a like a 460 (dad's truck). But then the air filter on the 911 is 2x the size of the truck.

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Ted Stringer
nuke3@juno.com
'84 911 Targa aka pocketrocket

[JoeF]

I tried a K&N on a 79SC, I cant really feel any power increase, but it did make the
more quiet.

[Joeaksa]

I have a MSDS (K&N clone)air filter on my 85 911 and did not do it for a gain in performance.

The stock air filter on the DME cars fills the back right side of the motor compartment. Replacing all this with the "cone" air filter makes it to where I can get to things and work, as opposed to coming out of the area with scratched and bloody arms and hands.

The entire time I had the stock air filter on the car getting to the bottom back latch on the housing caused me to cuss more than any other bit of maintenance I have ever done!

Will I have to clean it more often than just throwing a stock element inside? Yes, but its worth it for me to be able to get in and work for a change!

They claim an additional few HP with the filter but I did not really notice any change.

Just my 2c worth...

JA

[911pcars]

Just wanted to remind everyone that the alternative to paper filters isn't just a K&N "FilterCharger" (also paper/cotton gauze, BTW). There's also reticulated foam material (e.g. ITG and others) that filters better AND can also be cleaned and reoiled.

Many years ago, I acquired a couple of used K&N individual filter housings for my Webers. They originally had Filtron foam filters which are now out of business (at least they don't sell this size anymore). I was so unconvinced of K&N's claims that I purchased a couple of generic foam elements from Amsoil and fabricated them to fit inside the K&N housings. Today, ITG makes a nice setup for MFI or Webers.

For what it's worth
Sherwood Lee
http://members.rennlist.org/911pcars

[Wayne 962]

I agree. Whereas the Cool Collar appears to work in tests, I have no such faith in K&N air filters, and do not really recommend them. Firstly, they do not filter as well as the stock filters (33% increase is correct), and second, they do not give the HP gains reported.

The primary advantage of the K&N filters (as carnut169 pointed out), is that they are cleanable and reusable. Perhaps if you cleaned your filter often and didn't need to buy one, then the effect of having a clean filter might help your car?

-Wayne

[Clark Griswald]

Actually, going from 98% filtration to 97% filtration is a 50% increase in unfiltered particulate.

[movin]

You have to consider the particle size passing through for a meaningful comparison. It's not the % increase so much, but the particle size. The % increase in this case is at the extreme end of the spectrum, smallest. Just like oil filter specifications, you reach a threshold where the particle size is no longer considered detrimental and that's acceptable. No filter is 100% efficient. What's important is that no particles above a specified size get through.

[This message has been edited by movin (edited 08-10-2001).]