Metallic air filters

I see aftermarket air filters made out of some sort of metallic mesh that
claim to boost horsepower by allowing more air into the system. Hype? Any
value? Any problems?

 

I would seriously question their filtering ability.

A filter that doesn't filter as well and lets more dirt into your engine
does your engine no favors.

Also, understand the filtering efficiency numbers.

Lets say that we have a filter that is 95% efficient at filtering out crud,
and one that is 80% efficient at filtering out crud.

Not a significant difference, right?

Nope.

The 95% efficient filter passes 5% of the crud; the 80% efficient filter
passes 20% of the crud (that's FOUR TIMES MORE).

Keep this in mind when you look at filtering efficiency numbers.

 

Keep in mind that the engine is set up to operate with a certain
filter. The fuel-air mixture algorithms in the computer assume a
particular filter and will not be as optimal with one that is
"looser" or "tighter".

 

The stock PCM watches the engine sensors and can maintain the proper fuel to
air ratio regardless of most of the bolt-on aftermarket parts you may add to
it. While switching filters to a more performance-oriented model may reduce
it's filtering ability slightly, it can also provide a nice bump to hp &
torque (and subsequently, mileage too) if you replace the restrictive stock
intake box and filter. When our club gets together and dyno tests our cars,
we often see SPS's powerstack intake free up an average of 7 or 8 horsepower
on an otherwise stock car. And that's horsepower measured to the ground.

Lane [ l a n e @ p a i r . c o m ]

 

The stock PCM watches the engine sensors and can maintain the proper fuel to

What Lane said.

The K&N's are great......

 

To add to this, what Lane and Kirk said. I recently was shopping for a
Ractive filter and saw the choice between a paper/oil type or a stainless
steel mesh cone filter.

I asked my bro who is an old mechanical tech with lots of engine modding
experience. He first said that more aire + more HP, but it is equally
important to protect the intake system from garbage. Using an inferior air
filter will in time allow dirt buildup in your TB and beyond, messing up
injectors and more.

There are many high-flow filters out there that will filter efficiently
while letting in tons of air. K&N seems to be one of the most popular
filters. I question the filtering efficency of Ractive, APC and Pilot
filters. Ractive does make a cloth/ steel mesh cone that is intriguing
though. Most of the high-end intake systems come with a K&N filter, so that
should tell ya what is the preferred type of filter.

marx404

 

The K$N's will pass a butt load of dirt also. And you'll never notice the
power or mileage difference because of the lesser restriction.

 

Steve said: "The K$N's will pass a butt load of dirt also. And you'll never
notice the
power or mileage difference because of the lesser restriction."

I have "heard" this before, but not been provided with any proof to back up
this claim. Can anyone back this up with solid proof? I dont mean "I think I
read this somewhere" or "my friend races cars and he said", I am talking
hard evidence to prove that a properly maintained K&N filter allows alot of
dirt through, or does not work as good as the oem filter. Prove it with hard
facts please, I would like to know.
Thanks.

marx404

 

well i have a K'n'N in my silverado and have noticed NO difference what
so ever.
only reason i bought it was summit racing gace 40 dollars off my next
buy since i was a new customer.
glad i didnt pay full price for it and the charge kit.

 

I thank you for stating that. The people that actually were ripped off for
their hard earned money will not admit that there was no change. As for the
proof of dirt passage, all's I can say is look in the throttle body after 20
or 30 thousand miles. It's no secret that if you have better air flow
(supposedly) that you're going to pass more dirt. Cummins will not warranty
an engine that has a K$N filter on it.

http://www.cummins.com/na/pages/en/....cfm?uuid=00060D72-0093-1B8D-BCF080C4A8F00000

 

well i will admit when i am wrong,
now others might have a different story BUT for me it did nothing.
so i guess i am one that bought into the snake oil con, so to speak

 

....since low-flow filters can offer small gains, you probably would have to
perform a before and after on a dyno to see the numbers.. I don't know how
to go about proving one way or the other about low-flow's allowing more crud
to get into the engine than a paper filter, and or what the damage might be.
I'd think K&N would have done some development in that area if for no other
reason than to keep them out of court.

My 2 cents.

 

See http://www.knfilters.com/powertesting.htm .

"Specific testing documents that support any particular claim are
available upon written request." Why not write for details.

http://www.knfilters.com/faq.htm#1 - No actual claim of an increase in
gas mileage with K&N Filters.

http://www.knfilters.com/faq.htm#2 - K&N filters are designed to provide
a 2% to 4% horsepower increase, but they don't actually claim that they
will provide this increase in all cases.

http://www.knfilters.com/faq.htm#10 - This includes a long discussion of
filter efficiency testing and quotes an efficiency for K&N Filters. A
vauge claim is made that "With proper cleaning K&N air filters will
protect your engine for the life of your vehicle." They don't provide
you with a reference to let you decide if their filters are better or
worse than paper filters. The filter efficiency range quoted varies from
97% to 99%. Most engine manufacturers specify a minimum of 98.5%
efficiency (at least Baldwind makes this claim). A good paper filter
will be over 99% (AC claims 99% for their filters). You should also read
http://www.knfilters.com/facts.htm#RESULTS . This has more facts and
they mention that some paper filters have efficiencies as low as 93% -
unfortunately they don't mention the brand - I would not want to use it.

Ed

 

Thanks Ed - I never put that much thought into it. I did skim thru some of
the text in the links.

I wanted something aftermarket for looks as much as possible performance
gains (don't really care about fuel mileage). And I was okay with the cost
even if no gains could be determined (I never have put the car on a dyno
either).

I remember seeing an electric air cleaner assembly for dunebuggys, however
don't know what type of element it used. We use/sell paper elements at work
for the gas turbines. However the air cleaner assemblies are big enough to
walk into too.

 

....fat fingers here - sorry if this is a duplicate post.

K&N makes some refs to methods of how they test and customer testimonials.
And the Cummins site says piston scoring is the result of using an increased
flow filter such as K&N. Is there something different about a diesel engine
that makes it more sensitive to crud in the intake over a gasoline engine?
Or is Cummins the only engine maker who makes this claim. The K&N did not
void my warranty on my Saturn.

Paper filters supposedly filter down to smaller size particulates, however
their flow reduces as they get dirty. The K&N does not suffer from that
problem and allows larger particulates to pass. I just don't know how clean
air has to be for an engine.

Maybe the tradeoff is that if you'll do anything to get more power a less
restrictive air filter is one option. If longevity is want you want then
you want better filtering and maybe a paper-type element is a better choice.

Thanks for the links.

 

Well this turned out to be a long thread, lol! Thanks for your efforts,
although as I feared, nobody was able to come up with any hard scientific
facts, only a diesel manufacturer who claims that unfiltered larger debris
will score thier pistons. Otherwise, we have only found inconclusive
statements from users and K&N testimony (which I don't trust thier testimony
not to be biased either).

Paper pleated filters will ultimately capture more dirt and debris,
naturally. And naturally, the tighter the filter mesh, the less air flow.
More airflow = more HP, just ask your neighborhood old-fart hot rodder who
was doing it back in the 50's. Just ask an aviation engineer. (my 50+ bro is
one, hes nodding his head right now).

What this naturally means, is any air filter that allows more air to pass
through will filter less parts per micron (ppm) ergo, letting in larger
particles through to the throttle body. So the REAL question we should be
asking is "What is an Acceptable amount of ppm for a Saturn intake?" vs "How
many ppm does a K&N allow through?".

Cummins is correct, not bright to put an oil-covered filter on a long-range
hauling road vehicle. Is a Saturn a heavy diesel rig driven cross-country
for days at a time? No. This is not a fair comparison. Also, take
environment into consideration, if you are driving on dirt roads, you dont
want an oil/cloth based filter, again why a K&N is a stupid idea in a Deisel
engine, too many ppm, Diesels cant handle that as well as most gas engines
can (if properly maintained).

As far as Steve says, well, if you are going 20 to 30 K before properly
maintaining your K&N filter and your TB, well umm, nuff said there. After
20-30K mi, even with a paper filter and especially in city conditions, you
will get a dirty TB no matter what.

So again, the only actual written literature on thia subject is K&N's own
biased testimony. I have seen it. I called them and they would not tell me
what brands they tested against. Nonetheless, if K&N has been on running
cars for so many generations, if they are so terrible, why are they still in
business?

The best filtering is a foam filter, then a paper corrugated filter, then a
cloth mesh / oil filter. Again, more airflow = more ppm unfiltered, BUT if
you properly oil and maintain your K&N filter, the oil should serve to trap
the dirt before it passes through the filter, thus making it almost as
efficient at filtering as a paper filter. More dirt captured in the oil =
less apertures in the mesh = I dunno but K&N says more filtering.

Now Rumour Time: I have heard it said that tests by competing companies are
done using improperly or non-oiled K&N filters, thus making the test
invalid. I have heard from drivers that use K&N that say they dont oil thier
filters as scheduled or sometimes not at all! And then they complain about
dirt!?! Hmmm. Errrr....

Truth is, it is a balancing act, "more air or more filtering?". But I still
have no proof that K&N is bad.
Well, apologies for the long rant. Looks like we need to dig into this
further to find cold-hard facts. Share when ya find 'em, I'm looking too.
marx404

 

Good post.

On the assumption that paper filters clean better but are more restrictive
(and get progressively worse as they get dirtier), then one way to retain
the filtering ability and increase air flow is to increase the surface area
of the filter media. If you could double the size of the OEM filter
assembly (or put a couple of OEM units in parallel) you would probably get
the best of both worlds. Then the problem becomes lack of space... And
for fun add a flow meter with an idiot light/display on the dash saying
something like "Change engine air filter soon..." when flow reduces
indicating a clogged filter.

I bought a bagless vacuum for the house last year, one of those with the
plastic container you empty when it gets full. It has a HEPA filter too,
which is great for my lungs. I equated bagless with no maintenance, and
only after I noticed my new vacuum wasn't pulling anything up did I discover
I needed a new HEPA, plus a couple of other somewhat hidden, non-HEPA
elements. $20 later it worked like new. So like K&N who advertises a new
and better mousetrap, the vacuum maker talks about the pro's of bagless and
conveniently leaves out the need for filter replacement.

We use paper (or something resembling a paper product) filters for our gas
turbines at work - however the air cleaner assemblies are huge. Typical
turbine life is something like 30,000 hrs - and then they only need a
rebuild. Cool toys.

 

Diesels pull in a lot more air on average than gasoline engines. A diesel does
not have a throttle, so every intake stroke pulls in a full charge of air (or at
least as much as can squeeze by the valves. Gasoline engines are throttle and
most of the time, the cylinders pull in much less air.

Changing into a K&N can't void your entire warranty and in theory, the dealer
can only void the warranty on parts affected by the air cleaner if they can
prove the air cleaner caused the fault. This is only a theory. In practice
different dealers handle this differently. Almost all automobile warranties
include wording that allow them to void the warranty in cases of unapproved
modifications. This can only apply to parts of the car related to the unapproved
modification. For instance, the warranty on the power door locks is not affected
by the installation of the K&N filter. However, the warranty of the MAF may be
voided by installing a K&N. In theory the dealer would have to prove the K&N
caused the failure, but proof is nothing more complicated than having their
"expert" say it caused the failure.

As clean as possible is a good answer if you are looking for maximum life. On
the other hand, if you trade vehicles frequently, or drive in relatively clean
environments, or only drive a relatively few miles a year, installing a K&N may
have no adverse effects. I had a friend who owned a Lotus Super 7 with Weber
carburetors. He did not run an air cleaner at all - just wire baskets to keep
out the birds. The engine was still OK when he sold the car. But then I doubt he
drove it more than 3000 miles a year and only owned it for 4 years or so.

I agree. However, it is important to understand that it is unlikely that the K&N
will result in a detectable power increase - I don't think the average driver
can detect a 2% to 4% increase. If you are drag racing where 2% can be the
difference between winning and losing, then the K&N may be justified. I doubt
that it is ever justifiable for a street vehicle. And in most cases, there are
other modifications that will make a larger increase without possibly affecting
the life of the engine. My number one modification would be a better exhaust
system.

Ed

 

You can accomplish the same thing by installing a larger paper filter. The K&N
web site includes formulas for calculating the proper size K&N air filter for an
engine. The page includes a "filter factor" for the K&N filter and, until about
a year ago, also included a "filter factor" for a good paper filter. I used
K&N's formula, but with the paper filter factor, and determined that the paper
filter on my Mustang was already three times as big as K&N's formulas indicated
it needed to be to develop maximum power. So, what would I likely get my
installing a K&N filter? Almost nothing. Maybe, and I mean maybe, a 2 to 4
horsepower at WOT. If I was racing, this might be useful. On the street, it
most likely was undetectable and I could not justify the risks associated with
the K&N for the possible increase.

Ed