The Why or Why Not of K&N Filters?

All your questions will be answered here:

https://www.rcnitrotalk.com/forum/showthread.php?t=64253

For one thing those are not real K&N filters, I'd never use a clone filter like that on anything, from a Land Rover right down to an R/C car. They are likely just died paper that looks red like a K&N and I agree they'd just clog and let in the dust.

A properly maintained K&N Filter doesn't let dust through. That's the whole point of the K&N Filtercharger system. It gives high airflow without letting in dust, and has a long life and is easy to clean and maintain. If you buy a K&N Recharger kit and a filter it'll last you a long time for those little filters and you'll not get any dust invasion. Now wether you can find a filter that uses an oiled element and fits your Nitro very much depends how patient your local K&N retailer is. We've found them at work for guys, including, it turns out, the guy I travel with to crawler comps. He used to run 1/8th Nitro oval racing cars and used a K&N genuine filter and Filtercharger oil and told me he saw no increase in engine wear and wasn't constantly fussing about maintaining the filter, he just cleaned and re-oiled it using the K&N kit every few comps.

I know that's fairly anecdotal evidence, but I thought I'd at least test the water and see if there really is a genuine reason not to use K&Ns or if it's folklore.

Interesting info. Might be worth looking into.

Webbage said:

I know that's fairly anecdotal evidence, but I thought I'd at least test the water and see if there really is a genuine reason not to use K&Ns or if it's folklore.

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In all reality it's more folklore around here. I don't ever recall seeing anybody give hard evidence as to why not, but when 99% of the seasoned verterans say they are no good... well, "when in Rome".

I read WoodiE's post (K&N Air Filters = bad bad bad bad! - happened to be linked below in the related posts) and he has a good point I guess. The filters are only designed for gasoline engines. Without extensive scientific testing I can't hold up my hand and say they work or don't work for sure.

I think writing them off out of hand is kinda rash though, I just know we run them in everything at work, and they stop pretty much anything getting in. Assuming they only stop large particle dirt that is harmful to large engines definitely is not true, any dirt is harmful even to large car and truck engines, it all leads to wear over time. K&N make it clear their filters are designed t stop all dust, and not only that they *keep* stopping it over time.

Another unknown is if the system really scales down that small. I'd say yes it does as I know they do a lot of small filters for motorcycle applications which are only a little larger than a Weed Eater filter, for example and they work very well too. One of the guys at work runs one on his Honda VFR750 and swears by it.

I think the key is if you want to even try and use one, make sure it actually uses an oil element, I believe some of the breather filters (meant for filtering oil out of outgoing crank or cam case waste air) are not, or at least don't come pre-oiled. If you get one get a Recharger kit at the same time and clean and re-oil it periodically. As Nitro engines are very sensitive to the dirt then it makes sense to keep the filter clean even if it is a K&N.

Lastly, I won't dispute that Motor Saver filters probably are the best solution for a Nitro engine but I'll offer this also. We hate foam filters on grown-up cars because once the dirt gets in it some won't come out no matter how often you clean it. That dirt either clogs the foam and damages the filters efficiency, or works it's way further in and gets into the workings. That's a line on 1:1 car filters, but I believe it could apply to foam filters on Nitros too. One of the other things that makes K&Ns work so well is when you do flush the element, because it relies a lot on the oil to trap stuff, you wash the dirt out too.

I have zero experience of running them on Nitros, and if you guys don't recommend it and have genuinely found real K&Ns running real K&N oil and kept clean definitely still don't do the job then I'll hold up my hand and accept that.

Just my 2 cents/pence worth.

Webbage, I would give you two cents for your eloquence anytime!

Well, generally speaking I don't use a K&N style filter simply because it's outside of the proven norm. The gold standard for R/C engines is foam filters so that's what I stick with. Besides, all of my vehicles are off-road with the exception of my funny car project, which btw, I have a K&N style filter for. First of all, it looks great. Secondly, whenever it does run it'll be 10 seconds at a time in a relatively clean enviroment so I don't see a big give with the take.

I did run one K&N air filter for one tank on a track. I ended up throwing that thing as far as I could. It had let so much dirt in, that it looked like a mud bath in the intake. Just not a pretty result. I ended up losing a lot of compression, and the engine died in less than a gallon.

I've stuck to the two-element oiled foam filter ever since.

what about a k&n filter with foam inserts? would it still work? and actually keep dirt out?

HeartBreak said:

I did run one K&N air filter for one tank on a track. I ended up throwing that thing as far as I could. It had let so much dirt in, that it looked like a mud bath in the intake. Just not a pretty result. I ended up losing a lot of compression, and the engine died in less than a gallon.

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That's pretty bad. Was it an oiled-element type genuine K&N?

Webbage said:

That's pretty bad. Was it an oiled-element type genuine K&N?

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Yup, complete with red K&N oil. My guess (only a guess; I didn't look to verify at the time) was the paper was too thin, and had a hole sucked into it.

Check out these test results and decide for yourself. Sorry K&N I'll pass.

http://www.bobistheoilguy.com/airfilter/airtest1.htm

I just use k&n on my 1:1 cuz it makes a deeper tougher sound.







along with the flowmasters......

i just look at it that, a normal car goes up to about 6K RPMs give or take.

the normal Nitro engine is about 30K RPMs give or take.

so if the car and nitro manufaturers make filters the way they are for a reason. I'm not about to waist $200 and up to find out a K&N filter doesn't work on a nitro car. lol

all i know that it is a proven fact that the mini K&N filters are for Cars/trucks, not Nitro cars. although they do look nice on a shelf queen.

sweetdiesel said:

Check out these test results and decide for yourself. Sorry K&N I'll pass.

http://www.bobistheoilguy.com/airfilter/airtest1.htm

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I can't make head nor tail of that article. It's all waffle and not much stats. I'm sure if I spent 3 hours reading it I'd find out what you meant, but frankly I don't have the time and reading blue text on a white background made my eyes hurt
I've read some of Bob's stuff before and he knows his onions from his apples, but I can't even glean from skim reading it what he found out.

I guess from your reaction that K&N's filter didn't make much difference, or were overpriced and didn't perform? Or were you just taking the case and applying it to Nitros in particular?

As far as 1:1 cars go, I have genuinely seen and driven the difference between an OEM paper filter and a K&N in similar vehicles, and as far as I could tell the K&N flowed better and trapped more crap, and at routine service intervals they work one HECK of a lot better than the paper filter you would take out and throw away.

HeartBreak said:

Yup, complete with red K&N oil. My guess (only a guess; I didn't look to verify at the time) was the paper was too thin, and had a hole sucked into it.

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I wouldn't automatically assume that, it may just have been that the filtration wasn't good enough, that's what I'm trying to find out, and people seem to think it's true so maybe it just was not suitable.

Mattyfats420 said:

... if the car and nitro manufaturers make filters the way they are for a reason. I'm not about to waist $200 and up to find out a K&N filter doesn't work on a nitro car. lol

all i know that it is a proven fact that the mini K&N filters are for Cars/trucks, not Nitro cars. although they do look nice on a shelf queen.

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I dunno who's charging you 200 US for a K&N that small but they want beating up with a big stick

You are of course right, different applications have different 'tolerances', and 1:1 car engines are much more tolerant than Nitro engines and so you can get away with less effective filtration. If someone somewhere in a car company can cut costs somewhere by a few cents a filter they will, and K&N's application chart only takes these manufacturers values and tries to fit a filter to them.

I can fully accept that they aren't suitable, don't think I'm trying to defend them in any way, I just wanted to make sure the fact were straight, so if anyone asks me for a K&N for a Nitro (seeing as I work for a K&N dealer) I can tell them it's not a good idea, if required.