The final UNI vs K&N thread

[0101]

I was browsin around on a Jeep site (I own a Jeep) and came across this chart. Hopefully this will help end most of these silly threads regarding how well these two filter.

http://www.jeepforum.com/forum/3886876-post21.html

I still use K&Ns on my quads, but my jeep will definitely be seeing a AC Delco.

[honda400ex2003]

k and n for me, these are always good ones to follow and read so now i am subscribed. lol, steve

[0101]

Link is up haha

[honda400ex2003]

i saw it after posting it and edited mine already. lol, steve

[marineco]

my $.02... While this is a good indicator, and I will probably start using the AC filters now, I will ask this to spark some talk and hopefully learn something. How much can we really apply this to ATVs? Or jeeps for that matter. that test was run on diesels!

I am no engineer but I have to think that there is a huge difference in the air requirements of a big diesel built for pulling and a single cylinder gas engine made for speed.

So if I was a manufacturer I would probably know what those requirements were and design my filters to suit.

My basic overall thought being this. maybe they DID hose up the design on that one. but does anyone have similar tests on ATVs? Maybe K&N is the best or middle in that market.

Once again.. I know I am NOT an engineer. These are just my guesses and questions.

[0101]

Originally posted by marineco
my $.02... While this is a good indicator, and I will probably start using the AC filters now, I will ask this to spark some talk and hopefully learn something. How much can we really apply this to ATVs? Or jeeps for that matter. that test was run on diesels!

I am no engineer but I have to think that there is a huge difference in the air requirements of a big diesel built for pulling and a single cylinder gas engine made for speed.

So if I was a manufacturer I would probably know what those requirements were and design my filters to suit.

My basic overall thought being this. maybe they DID hose up the design on that one. but does anyone have similar tests on ATVs? Maybe K&N is the best or middle in that market.

Once again.. I know I am NOT an engineer. These are just my guesses and questions.

You do have a good point, however, the way I look at it is, all engines suck in air... It doesn't matter how much air it sucks in, or how little, the air will still need to be filtered. If the filtered air is dirty, then the filter wasn't doing its job.

I guess what I am getting at is, the type of engine shouldn't matter. Also, K&N's filters for cars (gas or diesel) are made of the same material as the ones made for quads.

[Muzzgit]

I haven't looked at the link to the jeep site but truck filters are only serviced every 10 thousand miles, or longer. A quad or dirt bike filter should be serviced very regularly, sometimes more than once a day depending on conditions.

Quad and dirt bike filters allow as much air as possible without dirt/dust particles getting past but because they are so small will only do so for a very short period before allowing crap to get into the engine or clogging up and effecting performance.

As an example, a banshee at full noise needs an air filter about the size of a shoe box to work at it's absolute best, but all we have room for is something about the size of a shoe.

Truck air filters are huge in comparison and are made to last for months, even years. Quite often they will have two air filters. Large truck engines can suck big volumes of air, and diesels need clean air more than petrol engines.

A small air filter will need to be cleaned & re-oiled or replaced more often, regardless of who made it!

Don't waste good money on overpriced air filters. Sure, buy good quality but more importantly :) clean it regularly !!

[0101]

Originally posted by Muzzgit
[B]I haven't looked at the link to the jeep site but truck filters are only serviced every 10 thousand miles, or longer. A quad or dirt bike filter should be serviced very regularly, sometimes more than once a day depending on conditions.
That is probably because most trucks are used on the road, while our quads are usually used in extremely dusty conditions.

[Snipe]

What I dont understand, Im a UNI fan. but with the K&N how can it clog faster and let more dirt pass through? I mean is that actually possible?

If there passing the same amount of dirt into each air system then if it was clogging to fast then to me it would be to restrictive and not let as much dirt in. I just dont see how it could do both lol.

[benjaminearl]

heres my .02.
deisels are turboed. they forcibily suck air. therefore actually PULL air through the filter. whereas a wheeler uses ALOT less negative cyclinder pressure to suck air through. i dont see whereas K and N are that bad. ive used one on everything for years and issues with dirt and i live on a dirt road. lol and drive diesel car and truck

[NacsMXer]

Originally posted by benjaminearl
heres my .02.
deisels are turboed. they forcibily suck air. therefore actually PULL air through the filter. whereas a wheeler uses ALOT less negative cyclinder pressure to suck air through. i dont see whereas K and N are that bad. ive used one on everything for years and issues with dirt and i live on a dirt road. lol and drive diesel car and truck

I agree with you on that one. I have a blown truck so I am somewhat familiar.

Naturally aspirated vehicles such as quads are only able to achieve "0" vacuum when they go WOT. If you were looking at a boost gauge, it would read 0 in Hg, which is equal to the pressure of the air that you and I breathe....atmospheric pressure. A turboed, or supercharged vehicle is able to draw in even more air in order to build up pressure that is greater than atmospheric...."boost".

In all simplicity, any time you are sucking harder through the same filter design, you will have an increased chance to draw more dirt through. Therefore I don't think that this particular test is DIRECTLY applicable to N/A ATV's. Examine the test results with a grain of salt.

[baker420ex]

even tho the test is for a diesel, i think the link still holds some validity. sure with a turbo air is getting pulled, or forced, through the filter, if anything the simile between the diesel and gas job filters would provide a fast-foreward effect on what you might expect to find in the future for your filter. the filter on the diesel is filtering way more air by cfm's than a filter on the quad. only thing is, most of those brands dont even manufacture filters for quads, and what's to say a brand like k&n put a little more r&d into their filter line for quads than they did for diesels...

does make me think about running my k&n though....i do have to clean it every couple of rides. i'd say like 5-8 hours of riding w/o a lid.

(from the link) "In 60 minutes the AC Filter accumulated 574gms of dirt and passed only 0.4gms. After only 24 minutes the K&N had accumulated 221gms of dirt but passed 7.0gms."

anyone out there with a uni or other foam filter how many hours do you ride before you NEED to clean your filter?? post your info.

[hypersnyper6947]

I did my own test a while back, i had it posted but will post it again. I road at the same place in the same dusty conditions. For the record K&N will never be on my quad or my diesel truck, EVER.

The pics are from inside the intake tube, i cleaned the tube and filter before riding on both

This is from a k&n with an outerwears cover with open air box

http://i74.photobucket.com/albums/i276/aclasson86/DSC06740.jpg

This is from a UNI with no outerwears and no lid
http://i74.photobucket.com/albums/i276/aclasson86/DSC06837.jpg
http://i74.photobucket.com/albums/i276/aclasson86/DSC06838.jpg


The little bit of dirt you see is from where i missed when wiping it out from having the k&n on, and those big pieces of dirt are from removing the filter and some falling in. Anyway you can see how much cleaner the intake tube is from the UNI and thats with out a outerwears.

[0101]

Originally posted by hypersnyper6947
I did my own test a while back, i had it posted but will post it again. I road at the same place in the same dusty conditions. For the record K&N will never be on my quad or my diesel truck, EVER.

The pics are from inside the intake tube, i cleaned the tube and filter before riding on both

This is from a k&n with an outerwears cover with open air box

http://i74.photobucket.com/albums/i276/aclasson86/DSC06740.jpg

This is from a UNI with no outerwears and no lid
http://i74.photobucket.com/albums/i276/aclasson86/DSC06837.jpg
http://i74.photobucket.com/albums/i276/aclasson86/DSC06838.jpg


The little bit of dirt you see is from where i missed when wiping it out from having the k&n on, and those big pieces of dirt are from removing the filter and some falling in. Anyway you can see how much cleaner the intake tube is from the UNI and thats with out a outerwears.
I did an almost identical test when I still had my 300ex. My 300 had a UNI and my dads 400 had a K&N. We both rode in the same conditions, but the UNI didnt have an air box cover. The tube of the K&N was coated with a layer of dust/dirt, but the UNI was SPOTLESS.

[hypersnyper6947]

yup, if that doesnt steer you from k&n i dont know what will

[baker420ex]

nice. looks like i'll be getting a uni.

[MtnEX]

Yeah, I think I am going away from K&N too...

I have found dust in my intake tube for the second time now. And I run LID ON.

To be absolutely level fair though, I'll have to prove it is the K&N... because it could be from where the vent tube connects to the intake tube also.

[Muzzgit]

Part of what I have said has been taken out of context but shi!t happens, I'm not gonna dwell on it. HOWEVER......

1.

[0101]

Originally posted by Muzzgit
Part of what I have said has been taken out of context but shi!t happens, I'm not gonna dwell on it. HOWEVER......

1.

However what?

[Muzzgit]

HOWEVER... well, yeah!

I don't know what happened, I was in the middle of typing and the screen dissapeared. I think I went fot the CAPS LOCK but hit TAB instead and it went FUBAR!

What I was trying to say was, any air filter is a compromise between clean air and performance. The perfect air filter would allow an engine to run at full power without any restriction, while not passing any dust what-so-ever.

But reallity is different, particularly when we have such limited space to fit an airfilter in a dirtbike/quad bike.

Also, it is quite reasonable to expect a truck engine to do 500,000 miles without a major rebuild. Try that with a quad bike!



NacsMXer...that's not quite right. Any engine, no matter what size, capacity or number of cylinders will create a vacuum. Even at idle.

At full noise, a 400cc quad would suck in quite a bit of air.

[NacsMXer]

Originally posted by Muzzgit


NacsMXer...that's not quite right. Any engine, no matter what size, capacity or number of cylinders will create a vacuum. Even at idle.

At full noise, a 400cc quad would suck in quite a bit of air.

I think you misunderstood what I was saying. If you hooked up a Boost/Vac gauge to your car quad right now and let it idle, the gauge would read somewhere around 20 in Hg of vacuum. As you step/push into the throttle, the vacuum on the gauge will continue to read less...15 in Hg (25% throttle), 10 in Hg (50% throttle), 5 in Hg (75% throttle), etc. depending on how much throttle input you are giving it.

The point I was trying to make is that naturally aspirated vehicles, at WOT, can only get as far as "0" vacuum on the gauge. If you let off the throttle all the way, it would go back to 20 in Hg vacuum at idle.....but at wide open, 0 in Hg vacuum is the limit for any N/A vehicle.

Think of vacuum as a negative pressure, and boost as a positive pressure. N/A vehicles can only go as high as "0" in Hg of vacuum (which means that it is in equilibrium with atmospheric pressure). Boosted/Forced Induction vehicles can go BEYOND "0" in Hg vacuum and into the positive pressure side into +1 psi, +2 psi, +3 psi ABOVE atmospheric pressure. The fact that more air needs to be drawn into the intake and pressurized to make boost, means that there is a greater suction of air through the air filter when the vehicle is doing so.

[Muzzgit]

I'm starting to loose faith in the K&N too.

Went riding two weeks ago. It was wet and slippery with a few puddles on the tracks, some too deep to ride across! At one point while riding, I had gone through a shallow puddle and the bike coughed and spluttered for a few minutes.

Finally got to clean my bike today and when I took the rear plastics off, the inside of the airbox was filthy and the outerwears was filthy.

OK I thought, it's done it's job, it's kept the crap out of the engine, but it hadn't! :eek:

The whole filter was wet and the inside of the intake tube was dirty and I had to take the airbox and intake tube out and wash them. That's the second time in less than a year!

I run without the airbox lid but today all that changes. Today I cut out the back 1/3 of the airbox lid so it's still open but water cannot fall directly onto the filter.

I'll check in a few months and see if there is anything in the intake tube. If so, I'm going back to the oiled foam filter.

[Jessem24]

you know, they say k&N have great air flow, but they dont filter worth S***!

im sorry but its uni for me :D

every one has there own opinion, and thats fine.

[Muzzgit]

I note the Uni filter let in more dust than the K&N :eek:

Sorry about the EDIT !

[RIDEREDson]

My buddy has a 250r with a 265 national motor in it. He has been running K&N's since he has had it. Regardless he's been running on the same top end for 3 years now. No rebuilds, no nothing. Still runs like a champ.

[Ryan'07400ex]

I bet that title doesn't hold true haha. We get this big test and it starts another debate haha.

I'm thinking the stock cleans okay :devil: although I may switch to a uni (just going with foam again since thats what stock is) because it is supposed to give better airflow over stock.

[witech]

Originally posted by Jessem24
you know, they say k&N have great air flow, but they dont filter worth S***!

im sorry but its uni for me :D

every one has there own opinion, and thats fine.


Who says K@N's have great airflow? Back when we started dyno tuning filter tests were first on the list. A K@N verses a 2 stage uni had virtually no difference in power. It could barely be measured in tenths of a horse going to the K@N. In fact on an engine pulling 55hp removing the filter completely in a pod system would only raise hp by 1 to 1.5 at the most on an engine making 55 hp. The majority of quads people own on here that are 25 to 45 hp . A couple of percent of that is less than 1 horse. Now why would you risk wasting your valves and rings for an nearly immeasurable gain. And what good is that gain when shortly after your losing power from the lost compresion.
The other issue with cotten gauze filters is their low capacity. Back in the day before we knew better we went on some trail rides where you wouldnt make it ten miles before the quad was gasping for air due to a plugged K@N. The foam filters not only filter better but have many times more surface area inside the foam cells to trap and hold the dirt. K@N only have very thin media sandwich with with just a small chance of catching anything . Dont forget about water and moisture. Cotton swells up and plugs when it gets wet.
Needless to say we run 2 stage cotton for all our trail and race engines.

[hypersnyper6947]

Originally posted by witech
The foam filters not only filter better but have many times more surface area inside the foam cells to trap and hold the dirt. K@N only have very thin media sandwich with with just a small chance of catching anything . Dont forget about water and moisture. Cotton swells up and plugs when it gets wet.
Needless to say we run 2 stage cotton for all our trail and race engines.

Did you mean 2 stage foam at the end there??

[witech]

LOL foam .

[MidnightBlade]

ya if you put a foam ball in your airbox and take off the filter (dont do this often) it will suck the ball up to the intake at about3/4 throttle, if you can find a way to hold the ball inside the filterit gives you maximum air cleaning in limited space.

[Snipe]

Well K&N will flow better and not clog as fast that is becuase there more coarse but think about it being more coarse will let bigger particulates into the motor. Its simple thinking, bigger = more flow more flow = dirt in motor. Its up to you if you wanna risk it, thats why I run UNI.

I have never had a problem with my K&N/Outerwear combo in extremely sandy and dusty conditions. Actually it hasnt failed me or made my motor blow in all of the things I have put it through. Thats not just 1 400ex either that i'm talking about, theres another in the garage that has been running a K&N even longer still going. I think most of it is maintenance. You shouldnt slack with air filters regardless of brand or type, every ride it should be checked and if needed vacuumed or completely washed and re-oiled. For road applications where the dirt and dust isnt even close to what offroad vehicles see K&N seems to be a winner. Its just nice having the warranty and a sturdy product that you know will last. In my car I actually switched from a foam cone to a K&N cone. Both filters were the same price and after seeing what the foam looks like after so long I chose something that would perform a little better and last. To each is own, I choose K&N and have yet to have problems in many years. Some feel more secure with a foam filter.

[MtnEX]

Sand is not a small particulate.

Dust off clay soil... that's a different animal.

[Snipe]

Exactly. Here in the ozarks we have lots of granit, chat and limestone the forms the ozark mountains and causes lots of dust in the dry season on dirt roads. Itst horrible to imagine sucking that in my motor.

Yea you might had switched to the K&N cause it stayed cleaner longer but think I mean really think as to why it stays cleaner longer....

[Muzzgit]

You're right man! A good air filter will catch all the sh1t and look terrible..... I'm not interested in what the air filter looks like after a dirty days ride..... I'm interested in what the intake pipe looks like!

If the intake pipe is dirty, then the air filter is not doing it's job.

I have been chatting to a few guys here in Australia who ride some of the dusty desert races. A couple of them wrap oiled Chux wipes around the K&N filter and simply peel off one and replace with another layer as the day goes on. Cheap and simple.

The K&N stays clean but the wipes are are full of crap every time.

[witech]

Well lets put it this way .If you NEED to buy an air filter to put around your air filter ........LOL

[baker420ex]

i've run a k&n for most of this summer and i'm switching back to a foam filter.
i spray my filter out and oil it regularly, and the box about every other time and from what i've seen it's time to switch.
the k&ns are hard to clean because of their design, to get into each crease with the air it takes longer than it would to clean a foam filter. and the creases are basically pockets for dirt and dust. mine is noticably clogged after just a few rides. i dont mind cleaning my filter regularly, but i've noticed a good amount of dirt is passing through the filter, because i've been spraying the inside of the boot with oil...so anyone who says k&ns are the best is pitching a biased argument.

[VTredneckgames]

Is the stock filter really that bad? Or does people swap to a uni because they want a new filter?

Why not just clean the stock filter and re-oil? Is the stock filter that much more restrictive then the uni or k&n?

I used to think that uni was just an aftermarket stock replacement. And I thought that K&N was the performance replacement. (used to think is the key guys, dont flame me, I have no preference over one or the other)

[NacsMXer]

Originally posted by VTredneckgames
Is the stock filter really that bad? Or does people swap to a uni because they want a new filter?

Why not just clean the stock filter and re-oil? Is the stock filter that much more restrictive then the uni or k&n?

I used to think that uni was just an aftermarket stock replacement. And I thought that K&N was the performance replacement. (used to think is the key guys, dont flame me, I have no preference over one or the other)

The stock foam filter isn't extremely restrictive, but it is smaller than the UNI filter. It also doesn't have an "open" end cap on it like the UNI (stock has a closed rubber cap, UNI has an open foam top). The K&N is dimensionally similar in size to the stock filter, but flows more simply because of the thin layer of cotton gauze filter media.

[dirtking]

i myself say that K&N air filters are pretty good i have a 2001 400ex bought it new and the day after i bought it a K&N air filter went on it. now 8 years later it still runs like a top and i never bought a new airfilter. i used the same one for 8 years!!!!!!!!
so i consider K&N to be just as good of a choice as UNI.

[Muzzgit]

After riding through some muddy wet tracks and finding that my K&N was completely wet, I have put the airbox lid back on, but I cut some large holes in the rear of the lid. Now any water splashing up under my seat might get into the airbox, but at least it won't land directly ON the filter. After the weekend I can say it has been a success.

However, I still found dirt particles in the intake pipe, which means the K&N + outerwears is not very good at filtering !!!

So, I conclude that I have wasted my money on this filter and also I may be causing premature wear to my engine.

[Shawthy33]

What is the point of putting the lid back on if you just drilled holes in the back?

Just curious, it would seem that the "performance" boost of the holes is not worth the risk of sucking up water/dirt into the filter and motor

[katch26]

no matter how many of these threads there are it will always come down to maintenance. They both use BOTH mechanical and chemical methods to filtrate so if its not oiled or under oiled it will make all the difference in the world. I run the uni on the 400 and the k&n on the pred and at the end of the day the honestly look the same.....BUT I clean/oil them prior to riding every time. IMO the majority of people who worry about the K&N filter letting in dirt are the same people who push the envelope with scheduled maintenance. Power always comes at the cost of reliability so if reliability, or filtration in this case, was your number one priority you would never even take the seat off.

[texasman20]

slightly off topic but will i have to rejet if i were to only upgrade the filter?

[MidnightBlade]

ya youll probably have to rejet because any change in fuel air mix makes it run different if it runs too lean on fuel it will ruin your rings and piston if it doesnt get enough fuel it runs too hot and melts them