WHAAAAT? A DOWNSIDE to K&N filters?!?!

[dlaing]

Articles showing more power for paper filter than BMC

http://www.svrider.com/articles/2000jul_tybt.htm

http://www.rc51.org/dyno/bmc.htm

And dyno charts from BMC

http://www.bmcairfilters.com/VisDyno.asp

[mike wilson]

FWIW, my take on filters.

 

The original Guzzi filter system was the most unmitigated piece of convoluted, plastic garbage ever fitted. It did two things well: filtering (when assembled properly, which is not easy to do) and reduction of intake roar. Maintenance is an absolute nightmare. It's quicker to change a tyre than an air filter.

 

Changing to (whatever brand) filters attached to the carbs makes life so much easier wrt maintenance that I would be prepared to put up with reduced filtering performance. Which brings me to the tests.

 

As has already been pointed out, the difference in filtering ability between the best filterer and the K&Ns is about 3%. That is a liveable number for me. My bike is going to wear out 3% faster? No problem. Except, of course, that is not entirely true.

 

Investigation by the Transport and Road research Laboratory (TRRL, now the TRL http://www.trl.co.uk/default.asp) in the UK showed that it was not only the amount of dust that mattered but its size. The ideal particle to cause wear is one that is just bigger than the gap between the things that it is going to damage. Examining a number of filters then available (this was late 1970s) no appreciable difference was found in the filtering ability wrt the particles that would cause most damage in an IC engine. Sure, there were small percentage differences but all the filters tested removed virtually all the particles. Rather like the ones in the present test. I can only assume that filtering abilites have improved since then.

 

For me, the virtues of ease of maintenance (which will therefore be done - I have seen three Guzzis running excessively rich due to blocked original filters) far outweighs the small deficiency in filtering capability.

 

What I _really_ object to is the outrageous price of the things!!!

 

mike

[Guest ratchethack]

Articles showing more power for paper filter than BMC

http://www.svrider.com/articles/2000jul_tybt.htm

http://www.rc51.org/dyno/bmc.htm

And dyno charts from BMC

http://www.bmcairfilters.com/VisDyno.asp

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Interesting stuff, Dave. Tiny differences in peak power at WOT.

 

But again, 2 key points that many seem to be missing.

 

1. Like many Guzzi riders (if not most, I suspect a significant number) I'm neither going for a land speed record, chasing peaks on a dyno chart, nor racing.

 

2. Like many Guzzi riders (again if not most, I suspect at least a significant number) I seldom hit WOT, and when I do, it's usually for a max of a few seconds every couple hundred miles at most.

 

For my purposes (and I suspect for many others as well), when it comes to air filtration for my Guzzi, engine protection far and away trumps any tiny differences in peak power production at WOT. I'm sure there are many alternatives to BMC that would protect the engine just as well, maybe better. But I'm also pretty sure that K&N ain't one of 'em.

 

BTW - For those who ARE racing, going for land speed records, or just obsessively chasing every tiny rise in horsepower peaks on dyno charts - Why would you ever choose an air-cooled pushrod motor, or are you segregated by racing class? Aren't you setting yourself up to be absolutely clobbered by nearly anybody you're competing against? Seems to me you can find a clapped-out 10-year-old water-cooled 16v DOHC Japper 4, and with a relatively small amount of cost and tuning, probably double any output you could ever hope to get from a V11.

 

BAA, TJM, & YMMV

[Guest ratchethack]

As has already been pointed out, the difference in filtering ability between the best filterer and the K&Ns is about 3%. 

Mike, from the Dirt Passed v. Total Test Time segment of the test:

 

"Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. See the data tables for a complete summary of these comparisons."

 

This is significant, and I expect it would be significant to engine life.

 

Also, one test I read awhile back measured particle size passed by many common filters, including K&N. The K&N's passed an average particle size 3 times larger than the average of all of the filters in the test.

[mike wilson]

Mike, from the Dirt Passed v. Total Test Time segment of the test:

 

"Compared to the AC, the K&N  “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. See the data tables for a complete summary of these comparisons."

 

This is significant, and I expect it would be significant to engine life.

 

Also, one test I read awhile back measured particle size passed by many common filters, including K&N.  The K&N's passed an average particle size 3 times larger than the average of all of the filters in the test. <_>

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Except those dirt numbers are looking at the figures from the reverse end. The magic of statistics, again. You can say that the K&Ns were 3% less efficient or you can say that they passed 18 times more dirt. Which end you look at depends on whose marketing department is writing. If the figures are based on a nearly 100% efficiency, _in the real world_ how important is it?

 

If I really wanted to hammer K&Ns with the numbers available from this test, I would say that they passed ~90% of passable dirt.

 

I would be very interested in an analysis of the size of the dust particles passed and collected by each filter. IIRC, the size for IC engines that was most harmful is about 10 microns.

 

BTW, I'm not particularly defending K&Ns here. I am assuming that all the other makes listed are "standard" filters that go in the OEM filter holder. As far as Guzzis are concerned, that (the OEM) is what I am against and the K&Ns are a less than perfect, much better solution to air filtration. If there is a better option (i.e., better filtration, longer life, CHEAPER) then I am right behind that. AFAIK, K&Ns are the only solution available here in the UK.

 

mike

[helicopterjim R.I.P.]

MY turn!!

 

I am too lazy to read it all again so I just want to know what kind of filter you do use, Mr ratchethack?

 

Has anyone ever noted in all these studies that they are mostly done under controlled conditions but seldom real life conditions? Try testing a paper element filter in high humidity conditions (ie. west coast of North America) and you will not want to use one ever again. They lose up to 40% flow capacity. That is why I prefer a filter like BMC or K&N because they work much better in the real world. Paper works great if you live in a dry environment like Arizona though.

 

Someone said look at your K&N without oiling it and you will never use it. Agreed!! I will never use it without oiling it. The reason you oil it is to give it its filter qualities.

[al_roethlisberger]

I wonder how well UNI filters compare to K&N filters?

 

The little I've read is that the UNI filters do filter a good bit better, but don't have a huge downside in reduced air-flow... if so

 

Anyone have any objective(non marketing) info on the UNI versus K&N?

 

al

 

 

P.S.

 

I won't even wade into the argument of whether K&Ns filter "well enough" or not. I've had them on my bikes for years with no known ill-effects(the FJ1200 had 80k miles) and I like them on the Guzzi for mostly aesthetic reasons.

 

If I were 100% concerned with ultimate filtration or filter/air-flow performance, I wouldn't be running pods at all

 

So this is somewhat of an academic discussion for me... now where's my popcorn smilie when I need it

[big J]

Ratchet, google up David Vizard and see what you find. He's well respected both sides of the pond for independant research. I've got a couple of his books and have been reading his tech articles since I was a nipper.

I could scan and copy the air filter tests but frankly I can't be arsed.

He shows a properly oiled and fitted K&N outperforms others.(as Jim says,they must be oiled to work) I could get a K&N here,so I fitted one.No others are available afaik locally. I've fitted them to other engines and have always had good results.

You dont like them.Dont fit one,then.

 

I'm struggling to see the relevance of all this. On a big air-cooled engine like ours,ring wear by unfiltered air shouldn't be that much of a problem,surely. If as you have said in the past, you typically keep the revs between 4-7000, you'll be replacing the rings round 60-70,000 miles anyway.

 

BTW,I didnt bother reading all those graphs and stuff,but I assume the guys who performed the tests did oil the filter. Didnt they?

[Alex-Corsa]

Its intake valve guides that suffer most from un/underfiltered air...

 

 

Hats Off to you ,BINGO- I am impressed, now that's something usefull that came out in this thread.

What do you suggest as best solution in air filtering??

[Alex-Corsa]

FWIW, my take on filters.

 

For me, the virtues of ease of maintenance (which will therefore be done - I have seen three Guzzis running excessively rich due to blocked original filters) far outweighs the small deficiency in filtering capability.

 

mike

 

That's a question that has to be asked.

[dlaing]

Ratchet,

What makes you think the BMC filters out more dirt?

I suspect the weave of the cotton is tighter.

[dlaing]

If I really wanted to hammer K&Ns with the numbers available from this test, I would say that they passed ~90% of passable dirt.

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But that is the K&N's self cleaning feature.

[dlaing]

Anyone have any objective(non marketing) info on the UNI versus K&N? 

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I was surprised that the UNI did so bad in these tests.

I remember reading an independent study that comapared UNI K&N and paper, and the K&N let the most air and dirt flow.

The paper blocked the most dirt, but some dirt passed early on because pores werent closed, and much later on, after the filter was saturated with dirt.

The UNI initially blocked more air, but after a month of service flowed better than the paper after a month.

I recall that the UNI kept the most dirt out of the engine and flowed very well for about a year.

I suppose eventually the dirt will build up and get sucked into the engine, as it did in the Test that Ratchet linked us to.

 

My other potential plan is to put a UNI prefilter over my BMC

[Guest ratchethack]

Well, Gents, I woke up this morning eagerly anticipating what this thread might have flushed out overnight.

 

Silly me!

 

I guess I got a level of response I was looking for alright, but Guys - if you're going to post every reason you can think of to defend K&N filters and knock the study I referenced without having read it, it puts me in the position of defending the study against every kind of argument imaginable (and some not imaginable) by pulling out quotes from the study and posting them so you can read 'em. Well I ain’t gonna do it. It’s just too tedious and I (for one) am gonna lose interest.

 

Not that this has degenerated into a full-blown emotional cluster****, (‘cause I reckon that’s not at all the case here) but down South some might call what this here’s starting to look like a “Tar Baby”…

 

Look. I didn’t write the study. There are lots of similar ones out there. If you actually read such things (as I do and evidently others on this Forum also do) you’ll not find that this study or its conclusions stand out in some unique way from the rest. If it did, some of the opposing posts that have surfaced might hold water. On the contrary, as I've mentioned, its conclusions fit in quite well with every credible study on the subject that I’ve read. And yep – I actually read ‘em, and I’ve been doing this on and off for decades. I read ‘em because I like to make educated choices whenever possible on this stuff. I reckon that’s why I’m here.

 

I'm not calling for everyone to throw away your K&N's, for God's sake. Isn’t this a Technical Forum? Isn’t technical data and analysis welcome here? I'm just attempting to bring some truth to an area that historically suffers from lack of it IMHO, and I’m backing up my clearly explained reasoning for my own position with one of the most independent and credibly conducted test studies I've seen.

 

Again, if you actually read the study and consider the source references and setup documentation, maybe you'll agree. Maybe you’ll change your mind about filters. Maybe not. It’s up to you.

 

I will say that it’s becoming clear whose ox is being gored here, Gents.

 

Please don't skim my posts for the first thing you find to disagree with and then attack my position and/or the study without having read either my post or the study! If you can’t take the few minutes required to read a longish post or a longish study, please don’t take the time to post your disagreement with them. And please don’t ask me to go off and research something that you think supports your opposing viewpoint without having read what it is that you’re disagreeing with! When you do this it indicates what I suspected all along. As I noted in my opening post - many people aren't doing any research whatsoever before making some level of "commitment to brand loyalty" or having any idea how filters compare to competitive offerings. That's fine. I was hoping to provide some useful information and discussion for those who're willing to use it and maybe benefit from it.

 

Making a commitment to a product and justifying it afterward by grasping at straws without any regard to the available facts ain't how I evaluate things, but that's just me. Some apparently have no regard for science, fact, or logic – or just avoid all effort and couldn’t possibly care less. To each his own.

 

Is selection of oil or brakes or tires or oil filters important? Evidently they are by the wealth of discussion here. I think so. Wouldn’t the selection of an air filter also be important, since like oil filters, they both protect the engine? I reckon Guzzi thought so too, because they actually put air filters on Guzzi's DECADES before they put oil filters in 'em!

 

I don’t know if engine protection is important to others, but it is to me. I reckon it should be if you plan on maintaining your Guzzi for many years, but that’s just me. Obviously for many here, air filters seem to be in an altogether separate category of relative unimportance. That’s fine by me!

 

To this point, we’ve seen posts in this thread that indicate that people select air filters based on the following criteria:

 

*The way it looks as a styling element

*A professional endorsement

*A more impressive power curve on a dyno graph

*My car ran stronger when I put Brand X in

*I’ve never tried any other

*The stickers

*The sound

*It makes no difference. Whatever gets by the filter rinses out with the oil

*Convenience of change-out

 

I note that none of these criteria have anything to do with engine protection. Not a one of 'em has ever shown up on anything like a serious evaluation of air filters to my knowledge. None of these are valid to me, but I’m certainly not everyone, but I wouldn’t condemn anyone for using any of them either.

 

OTOH, I believe that there may be others like me who prefer to actually base their product selections on the best impartial evaluation data they can find, appreciate a quality technical evaluation, and recognize appropriate evaluation data when they see it. I thought this discussion and the Duramax study might fill the bill. Since I couldn't remember any such discussion on air filters, I figured it might provide some value. If it doesn’t, by all means, please feel free to ignore it!

 

Some of the posts have evidently spoken from long experience and some depth of logical, unbiased analysis. These responses were most appreciated.

 

Many thanks to all who posted, Gents, for your kind consideration. Sorry for any unwanted acrimony. This was intended to be a friendly discussion.

 

Egg Nog does wonders for that sour stomach!

 

I think I’m gonna set this aside now.

[belfastguzzi]

I regard Science and Law as best guesses to date.  My education into Science, Mathematics, Electronics, Mechanics and Engineering have led me to the belief that we know fook all about most things we think we've figured out.

 

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Yep, you guys – your quiz points are all worthless, THEY'LL ALL WORTHLESS