K&N passed MORE dirt/dust and plugged up faster than just about every
other filter tested.
(Arlen) SPICER wrote,
"Now that I am not doing the tests and my objectivity is not necessary,
let me explain my motivation. The reason I started this crusade was that
I was seeing people spend a lot of money on aftermarket filters based on
the word of a salesperson or based on the misleading, incomplete or
outright deceiving information printed on boxes and in sales literature.
Gentlemen and Ladies, Marketing and the lure of profit is VERY POWERFUL!
It is amazing how many people believe that better airflow = more power!
Unless you have modifications out the wazoo, a more porous filter will
just dirty your oil! Some will say " I have used aftermarket brand X for
XXX # years with no problems. The PROBLEM is you spent a chunk of change
on a product that not only DID NOT increase your horsepower, but also
let in a lot of dirt while doing it! Now how much is a lot? ANY MORE
THAN NECESSARY is TOO MUCH!
Others are persuaded by the claims of aftermarket manufacturers that
their filters filter dirt "better than any other filter on the market."
Sounds very enticing. To small timers like you and me, spending $1500 to
test a filter sounds like a lot. But if you were a filter manufacturer
and you believed your filter could filter dirt better than any other
media on the market, wouldn't you want to prove it? Guess what. Test
your filter vs. the OE paper. It will cost you $3000 and for that price
you will have the data that you can use in your advertisements. Your
investment will be returned a thousand fold! EASIER than shooting fish
in a barrel! So why don't these manufacturers do this? Hmmm? Probably
not because they would feel guilty about taking more market share.
Now I am not saying that ALL aftermarket filters are useless. A paper
filter does not do well if directly wetted or muddy. It may collapse.
This is why many off-road filters are foam. It is a compromise between
filtering efficiency and protection from a collapsed filter. Now how
many of our trucks collapse their filters from mud and water? However,
if a filter is using "better airflow" as their marketing tool, remember
this....Does it flow better? At very high airflow volumes, probably.
BUT, Our trucks CAN'T flow that much air unless super-modified, so what
is the point? The stock filter will flow MORE THAN ENOUGH AIR to give
you ALL THE HORSEPOWER the engine has to give. And this remains true
until the filter is dirty enough to trip the air filter life indicator.
At that point performance will decline somewhat. Replace the filter and
get on with it.
I once found a site in Japanese where some creative street racers
decided to test filters. They used a shop vac, a measured spoonful of
copier toner, and what appeared to be coffee filters. As usual the K&N
was near the bottom in filtering ability.
They were also quite worried about MAP sensor failures on oiled air
filter equipped cars. Both K&N gauze type and oiled foam.
Its more extreme with a Diesel, as in the SPICER test above, but any
reduction in restriction (K&N's claim to fame) is compensated by closing
the throttle. Your engine requires one quantity of air per unit of work
and this quantity is regulated by the sum of the throttle plate, air
filter restriction, and other intake restrictions. Reduce restriction on
one and increase it on another to maintain the same quantity of air. So
unless your foot is pressed against the floorboard the air filter
restriction doesn't matter.
With the HP race automakers want every cheap horse they can find. If air
filters were as important for HP as K&N suggests then all an automaker
has to do is increase the size of their paper air filters. Bigger paper
filters flow the same volume with less restriction. Only example I know
of is the huge Porsche 928 air filter.
You are right the benefit of K/N is questionable. If it is that good, why
doesn't car manufacturer install them in their car? As far as increase
horsepower! all people have to do is to remove the air filter and try it out
to see if they can tell an improvement. Replace the filter after the test
run. My brother has purchased after market K/N cold air intake. We have
tested the car with and without using G-Tech (accelerometer to test for
acceleration). Test after tests, weather condition, road condition. There
is no benefit. We did not test its filtration ability but sound the copier
toner is a logical way to test.
I wont defend K&N officially however, the comment that you dont need
that extra air and wont benefit from it is ludicrous. More air, and
cooler air, to a point will get you more power, maybe not enough to
really notice.. 5-6 hp is probably about average. Why doesnt the dealer
put it on, because it gives a bit more growl with that extra flow. add
a CAI set up and you really increase noise. It all depends on the
vehicle. My Discovery runs just fine with the factory filter and being
that dirt is the issue on an offroad vehicle I would prefer to be safe
rather than sorry. However, a conical filter (not K&N) on a high flow
CAI set up produces noticible increase in high end power on every BMW I
have put them on, plus the roar you get with the CAI/foam filter is
I guess if the price is reasonable and you're not concern about if you
actually gain 5 to 6 hp than install one. But paying over 100 dollars is
bit too much for me. I wont say that I know a lot about engine breathing
nor know how to tune the engine to get extra horsepower with just 100 or 200
dollars. I thought that to get extra horse power you need air + fuel then
exhaust the burnt fuel out with less exhaust back pressure. So if that
case, than improving air does not necessary improve overall engine
performance. Ofcourse I am not talking about clog paper air filter either.
We have to assume that the stock air filter is clean and is representable
for this test. So change once per year is all you need for average driving
As far as CAI, once again not being the expert on this and since we are in
discussion mode, most CAI I have seen is placed inside engine bay. There is
no fresh air inlet from outside such as ramp-air to funnel the cold air in,
do you still think there is a cold air benefit? Cold air is better for
engine without question as it is more dense than warm air. I can see that if
you change your air intake ports or opening your throttle body or MAF sensor
to increase the cross sectional area plus air inlet from outside to get
cooler air, then you will see a benefit. I have a Bonneville SSEi. I have
removed the air filter, remove the MAF screen one day on open road to test
the car. With the accelerometer, I took several readings and the results
does not indicate with or without air filter to simulate an ideal filter
(stock air box) that there is an improvement.
We did the same test on Focus with Zetech engine but this time with full CAI
cone kit couple with 2 inches aluminum pipe. Once again, the results is not
Perhaps my accelerometer measurement resolution and accuracy is
questionable, but still the benefit between stock air filter vs CAI with K/N
or what have you is still out there.
Having said that, improve Hp does not come cheap with just K/N. I think
there is more to it than that.
There are two ways to know for sure and only two ways. One take the beast
to a shop with a dyno and put it on it, or two go to the drag strip and make
a dozen runs with each set up and see what the average times are. Races are
won and lost by margins less than a tenth of a second. 5-6 hp can be that
difference. On partial throttle, your not going to see a major difference.
Its when your toes are tickling the throttle plates the increased air flow
comes into play.
Check this link below to read other testimonials about K/N and its
benefits/not so good. I thought it is interesting...
Air + Fuel + Efficiency.
All other things being equil if you make the motor more efficient at burning
gas and turning it into power you get more power. It takes work to creat
the vacume that draws air in. Less intake restriction means more of the
motors power can go to HP. That's why K&N and any other means of less
restrictive air flow (and exaust from the push it out standpoint) increases
HP and MPG. Double stacking a standard filter should do the same thing. I
have to wonder why more people don't do that, or sell a kit...
As for why car makers don't do it, everthing they do is a balance between
making what it takes to sell a car and making money on the cars they sell.
You won't see a lot of tricks on stock cars because of that.
Lets say you are cruising at 80 MPH in your gasoline land ark at 3,000
RPM. Note your throttle position with stock paper air filter. Now
replace the filter with your choice of super non-restrictive filter and
note your throttle position under the same conditions. It is closed more
than previously because any and all restriction "saved" by the
"performance" air filter is compensated for at the throttle body.
Don't bother to actually try the above as you would have to be able to
measure the throttle position *very* accurately (the difference between
stock filter and no filter isn't much.) And then average the results
because under these conditions everything is always changing.
Under the stated conditions HP output remains constant. RPM remains
constant. The quantity of air does not change. The engine will suck air
on the intake exactly as hard with either filter. Look beyond the air
filter, the only point "restriction" matters is that which is seen at
the intake valves. K&N is happy if you only consider the restriction
between the throttle and outside atmosphere.
The only thing which is important is the *sum* of the intake
restriction. For a given HP output on a gasoline engine that sum will
remain constant because it is the very thing which regulates HP output.
If the engine gets more air the fuel system will add more fuel to
maintain combustion and emissions. More fuel = more HP = more faster,
where the driver compensates by lifting on the throttle to reduce the
air and therefore HP. The only time "less restriction" buys you anything
is under full throttle.
The link which started this thread was specifically interested in air
filter performance as related to Diesel engines. The intake equation is
different as the Diesel does not have a throttle. More air could result
in more efficiency.
On Thu, 06 Jan 2005 01:44:38 GMT, "Whitelightning"
I was thinking the same thing. Diesel is injected, just like most
modern gas engines. The main difference is ignition. It's like the
dude was trying to imply gas engines still have the air and fuel mixed
before entering the cylinders while diesels don't. Fact is, many
modern gas engines dont mix until in the cylinders either.
On Thu, 06 Jan 2005 02:26:20 GMT, firstname.lastname@example.org
they're both injected, but that's about the total of their
similarities. Gas engines still (with the exception of the Isuzu 3.5l
Direct injection gasser) inject the fuel into the intake manifold,
before the intake valve, whether it be at the throttlebody, like in a
TBI system) or at the intake valve (SFI, CFI, MPFI systems). Diesels
inject the fuel directly into the cylinder at extremely high pressures
( max injection pressure on a Duramax is 25,000PSI) at a precise time
in the compresstion stroke to fire the cylinder. Gas engines are
stoichiometric, i.e. they require between 12:1-14.7:1 air/fuel to
operate. diesels are lean-burn... meaning they can idle at a
75:1-100:1 a/f mixture.
a diesels engine speed is controlled by the injection pump, there are
no throttle blades of any kind. the pump controls the amount of fuel
and the timing of the pulses. the more fuel the faster the engine
runs, the available amount of air never changes. in a gas engine the
more air is allowed in, the more fuel is added to maintain the A/F
ratio, which increases engine speed.
On Thu, 06 Jan 2005 01:44:38 GMT, "Whitelightning"
I think he's referring to a throttle plate (used to restrict air
flow). Diesels regulate the fuel delivery & the only intake air
restrictions are in place to minimize noise levels.
If 5-6 HP is the be all and end all, purchase & install good oil for
your engine, tranny, & Diff. there have been independent studies that
have measured a 5-8 HP at the wheel gain from that alone. PLUS.
You'll save fuel & potentially increase the life of your mechanical
For the best results? Sell your present car & purchase a more
powerful car. Less monkeying around, better reliability, more power.
If I understood that at least somewhat. Carborated vehicles might see a
benift, but the ones with compuer controls will overide the filter benifits
to keep the motor operating wthin spec. So you would need a tweak in the
programming to realize the benifits?
This is a very interesting study. It displays the AC Delco filter in almost
the same light as others try to display the K&N filter.
Are there other studies out there like this? It is difficult to analyze one
versus another. But if there were three different, unrelated surveys and
they all pointed the same way . . .
Thinking twice about putting a K&N on my new vehicle. Maybe it belongs on
well power wise its more on a per engine basis than a lot of people here
give credit. my cavy had a highly noticable increase in performance with
a 10" round eldebrock muscle car filter set-up than with its original
set-up... and then when i got too gutting that cat on that one is was a
very even set-up ... not too much low and not too much high
Paul Proefrock wrote:
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