Air Filters: Do They Really Make A Difference?

[Guest klinquist]

Common sense tells us that more air flow = more power... but do a K&N or BMC filter really make any difference on the VFR (specifically 6th gen)?

I'm also a BMW (car) enthusiast and cold air intakes tend to give you almost no horsepower, even when paired with other mods. Of course, I know there are other cars out there that do get power.

The stock air filter looks pretty good. The K&N seems to have a smaller area. The BMC looks to be about OEM-sized. I don't like cleaning and re-oiling filters - I'd rather spend $25-30 on an OEM filter and replace it every 15k miles than re-oil a $75 filter assuming similar performance.

I just installed a PC3+coyze and have gutted cans on their way to me - just wondering if an air filter will 'complete the system' or if it's 'not really necessary'.

Thanks!

[Bassie]

You guys put oil on filters? I have never done souch a thing, why are you doing that?

Doesn't that hurt the airflow?

The filters being oiled are designed to be used after oiling.

K&N being one of the best known.

http://www.knfilters.com/

DON'T oil a conventional paper pleated filter.

Ok thanks mate, I didn't know that.

As I never used anything but paper before, I never came accross it.

[BusyLittleShop]

pipercross vs kn vs bmc vs oem

in that order:

Note that the K&N offers less filter area than the stock paper or the BMC... this is because the K&N flows more air and the company didn't want to cause fuel mapping complaints... so the K&N filer area is reduced to flow the same amount as a stock paper filter... if you wish to flow more air with an after market filter then pick the BMC... but it may cause fuel mapping issues...

[Guest]

I stick with OEM filters and I change them often. Motorcycle maintenance is not an area where I'm looking to pinch pennies.

I can't supply a link but I've read tests that show K&N allow a lot more dust and crap into your engine and don't offer any measurable performance gains.

I once worked in a GM service department and I saw plenty of Duramax diesels come in with blown engines that were diagnosed as "dusted" from using a K&N or equivalent. GM's policy was non-negotiable: void the warranty.

[spud786]

With oiled type filters, its the oil that actually does the filtering, so yeah there will be larger holes in the filter media, put oil on a regular filter and it will plug it up solid. I bought a EMGO filter for $25 shipped, that is identical to OEM. I havent installed it yet, but its due, I have about 18,000 mile on the present oem filter.

K$n is more a Cult following, they either suck dirt or plaster you valve stems with oil(carbon). THere was a Big test years ago with diesil offroad truck K@n didnt keep the dirt out.

K&N has a more efficient matierial for filter, hower the total area of the filter media is smaller so its a wash. However economically mine has paid for itself 3 or 4 times over, cleaning and reoiling is a snap and I dont have to waste my time taking a trip or spending time ordering a new oem one when it gets clogged up. Paper is fine but until sombody figures out a way to reuse it well enough the K&N is worth the money.

I use a K&N in every engine I own. Just for the money savings. Your noy going to get more power even if you run no air filter. If you do it will be so minor there is no diffirence.

Fact. K&N filters flow better once they get a little dirty.

LIke I said, it just saves money. A stock filter is $45, a K&N is $50 and you never have to buy another, pretty simple math, just dont expect 10 horsepower. Maybe more like a 1/10th of a HP.


I have never seen a dyno sheet from just an air filter that did much. My wifes car does seem to breath a lot better at high rpm's. More air with no more fuel equals nothing.

I thought dirty filter has more restriction compared to a new filter, hence replacing or cleaning filters such as K&N.

I'm still using my original filter, inspecting it every 15,000KM. I just tap and use compressed air and if the filter looks good I just reuse it. I currently have 67,000KM on my 1200.

Tried K&N for about 8,000 KM on this bike and didn't like dirt entering my airbox,compared to stock air filter. If you hold up a K&N air filter under a light you will see pin size holes and can see how dirt will enter the airbox.

[CandyRedRC46]

^^^ Jeez - I'm gonna inspect mine. --

- Gotta source for pipercross?

ebay :D lol

http://www.ebay.com/itm/130766710359?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

ebay seller

biketorqueracing

[CandyRedRC46]

I got my piper cross today. Looks of good quality. It was a little hard to fit, but it went in with some finess. A couple of the pros:

It used all available space.

It weighed almost nothing.

It is curved upwards, giving much more space for the velocity stacks than both kn and BMC, which both sit on the velocity stacks.

The cons:

$93

Difficult fit.

The red side faces downwards
The back side faces upwards

side notes:

for any of you clean freaks. although the piper cross filter media will out flow both kn and bmc filter media of the same surface area, it will also trap dust particles of smaller size.

holding up the piper cross to the light, you can not see through what so ever.

rebuttal to the diesel truck dusting warranty void claim by gmc:

piper cross has been oem equipment over the past 10 years for triumph.

[Guest]

I once worked in a GM service department and I saw plenty of Duramax diesels come in with blown engines that were diagnosed as "dusted" from using a K&N or equivalent. GM's policy was non-negotiable: void the warranty.

That might be a Canadian practice, but that would be highly illegal here in the USA - see Magnuson-Moss Warranty Act.

[timmythecop]

maybe slightly off topic, but....with today's science going into bike design, the pod filter is a thing of the past. I have seen dyno evidence of many modern bikes LOSING HP when the airbox is removed and individual filters are put on, but folks still do it. Sure, your KZ1000 benefited from it, but today's bikes are tunes with the airbox as an integral part of the equation. Also, since I am now a Seca2 owner I have been shown how all of those bikes have lost power with any change to the airbox and 90% of them have lost power with an aftermarket exhaust.

Turns out we are not smarter than those Japanese fellows in white lab coats.

[Mohawk]

I've read a lot of articles about airfilters & there is a great one where a car mag takes 8 of the available filters & puts them on a flow rig & measures the depression in the inlet manifold for each. The total varience is less than 0.1psi across the whole rev range ! The largest pressure difference was 0.06psi (0.03-0.09psi) ! So basically naff all.

The only ones that added pressure (i.e. reduced the pressure loss) had larger areas, so were able to flow a smidge more air, so it was NOT the media type that had any effect, rather the surface area of the filter. And as the recorded depression pressures were so low below ambient, they weren't worth worrying about.

Ramair systems can add 0.1-0.4psi (max) to the airbox & as bikes without ramair can suffer pressure losses in the airbox at speed of up to 0.5psi, then having it is worth while, with as much as a 1psi pressure between worst & best !

So adding a filter that can add 0.03psi more to a bike that could be losing 0.3psi at speed will NOT make things dramatically better.

Most bikes without ramair will be losing more in the airbox intake than the filter, which is why a common mod that has been tested on many bikes is to open the airbox intake, i.e. de-flapper & de-snorkel on the VFR etc.

Have fun. Remember you pays your money & takes your pick.

[Mohawk]

Here's a link to the Sportrider tests. This is a Blackbird going from stop to max speed, the black trace is MPH see right axis, the red is airbox pressure see left axis. Note the spikes, these show the sudden pressure changes when the power is stopped for each gear change & the pressure spike when the throttle is closed at max speed !

http://www.sportrider.com/tech/146_9910_ram/photo_07.html

Edited January 15, 2013 by Mohawk

[TomP]

Speaking of interesting reads, here's a link to an ISO 5011 test of various air filters. Granted, these are for a GM Duramax diesel truck, but the equipment and methodology make it fairly compelling.

"Compared to the AC (Delco), the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt."

http://www.billswebspace.com/AirFilterTest.htm

Tom