K & N Filter Yes or No ?

Might be coincidence, but both of the vehicles that I ran K&Ns in for many thousands of miles ended up being oil burners. First was my '84 Toyota Pick up and second was my '93 ST1100. Both were drop in designs to be used in the OEM air box. In the case of the Toyota I finally solved a poor gas mileage problem I was having by switching back to an OEM style paper filter. This doesn't prove cause and affect but it was enough to raise questions in my mind and so stopped using them

I had a Ford Racing Performance ProCal ECU tune installed in my 2013 Mustang GT. The package included a K&N drop-in filter replacement and I decided to try and compare the filtering surface area between it and a Purolator OEM style paper filter for my car.

First I measured the frame around the area of exposed filter media. This is the size of the opening if the filter media was removed. The K&N measured 6.6875" wide by 7.75" long for an opening area of 51.82 inches squared. For the Purolator paper filter, the frame was a bit more open measuring 7.25" x 8.25" for an opening area of 59.81 inches square.

Next I turned to the media itself which is mounted in a pleated arrangement in both cases. For the K&N the depth of each pleat was about 1.375" and the length was again 7.75" from above. There are twenty peaks. So 40 panels if you will, of the depth and length measured above. This results in a total surface are for air passage and filtering of 426.25 square inches.

For the Purolator the pleats were deeper, 2" in depth and longer at 8.25". The big difference is the number of panels, I counted 50 peaks or 100 panels of the above measured area for a total area of 1,650 square inches. That's almost 4 times the filtering surface of the K&N.

I have to conclude that either the K&N filter is actually more restrictive or it is 4 times more open than the paper one, to equal it's restriction, let alone best it. Now I understand depth filters but held up to a bright light I could see sparkles coming through the K&N, but not through the paper filter.

Some folks on the Mustang forums have dyno tested their cars before and after fitting the drop in K&N, most noticed no improvement in power in some cases a small loss. Now this may be in part due to the design of the OEM cold air intake fitted to the car, I don't know. But reading that report I cited and my own experiences have given me enough pause to not use them. There must be a reason that no cars or bikes (that I know of) come factory fitted with K&N or similar construction filters.

I put the Purolator one back in.

wjbertrand said:

First I measured the frame around the area of exposed filter media.

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This is only part of the issue. A better measure of the filter's efficacy is to measure the pressure drop across the filter and/or air flow under different levels of vacuum inside the filter. This replicates what the engine will see when air is being pulled into the engine.

I would GUESS that one reason we get paper filters is because the manufacturers are providing the cheapest and most effective way to supply clean, particulate free air to the engine. Or the CEO's brother is selling these filters to the company. Take your pick. I prefer the former, but am not surprised by the current lot of corporate malfeasance. For example, look at the recent flap over Wells Fargo employees creating unsolicited charge accounts to boost the profitability of the bank. And the CEO disavowing any knowledge of this practice despite the fact that it went on for more than 5 years. Or Takata airbags. or VW. Chevvy ignition switch failures? Take your pick.

My PO gave me a used K&N as a spare part, when I bought my '04. I have been using the oem filter that was in the bike all this season,, since it was nearly new. I have some experience with foam filters,, so I am going to clean up the K&N and pop it in for a test run on my "seat of the pants dyno". Should be able to get it done this weekend,, weather permitting. However,,, I will be comparing a dirty oem filters performance to clean K&N,,, which is not really fair. But it should be interesting. Here is a chart I stumbled across,,, for what it is worth,,, Cat'

SMSW said:

This is only part of the issue.

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Which is why I began with the word "First".

Both of my bikes came with K & N filters which I promptly replaced with OEM style filters. I?m concerned more that it will affect how the bike runs than extra dirt getting in. I replace them per the owner?s manual recommendation. I go with EMGO filters (which I?ve been happy with) to keep the cost down ? ordered one for the 1100 recently and it was under $18 ? Honda part is like $60.

RobbieAG said:

I replace them per the owner’s manual recommendation.

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That recommendation is every 12,000 miles, which IMO is waaaay too often. Here's a tip to save yourself some money, learned in auto shop in high school many decades ago. If you take a shop light and shine the light from the inside of a new filter, you can see how brightly the light shows through the pleats. As dirt accumulates, you will see less and less light getting through. When you can no longer see much light passing through at all, it's time to replace it. I generally find I get about 30,000 to 40,000 miles out of an OEM filter.

Ran K /N in bikes and cars with no issues whatsoever but to each their own. Reason why they make so many brands I guess. Get what you feel comfortable and use that.

Bush said:

That recommendation is every 12,000 miles, which IMO is waaaay too often. Here's a tip to save yourself some money, learned in auto shop in high school many decades ago. If you take a shop light and shine the light from the inside of a new filter, you can see how brightly the light shows through the pleats. As dirt accumulates, you will see less and less light getting through. When you can no longer see much light passing through at all, it's time to replace it. I generally find I get about 30,000 to 40,000 miles out of an OEM filter.

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I hear you but prefer the peace of mind of following the OEM maintenance schedule. It's only every other year the way I ride this bike and for the cost of the Emgo filter, it's worth it. I would think the light test would be pretty subjective and to know for sure, you'd need to get a flow test.

Well, the OP never came back with his decision on whether or not to install a K & N, but I see he has one for sale right now . . .

Re: K & N Air Filter Yes or No ?

I have one for years. I clean it once a sEason . I don't know 6 thousand miles or so.I have 3 bikes....anyway you wouldn't believe the amount of bugs and leaves that comes out! I would never let it go 30,000 miles! I would highly recommend buying one.Convenient! Have fun with the fantastic motorcycle.

Some time ago, and I can't remember the magazine or where I saw it, but on a dyno the K&N filter increased the horsepower by 6. Maybe someone else may have a better recall of that test.

KN let more dirt by. That's been proven.
Is it enough to damage your engine?
Depends on where you ride. The average street bike will take a long time to show any effects, if ever. If you spent much time off road or in dusty areas, the effects will show up sooner.
Slowly it will eat up the rings and oil consumption will begin. When depends on how much dirt enters the air box. Some may never get to that point as other parts wear out faster.

Bottom line is KN filters are a trade off. Get a reusable filter with maybe a slight performance gain for less filtration.

That dyno chart I found in post #43 was from an online motorcycle magazine article. Sounds like the one you are referring too. Cat'

or maybe this was it,,,

http://www.motorcycledaily.com/2004/09/21september04_kandnfilter/

NorCal_Ed said:

Some time ago, and I can't remember the magazine or where I saw it, but on a dyno the K&N filter increased the horsepower by 6. Maybe someone else may have a better recall of that test.

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Hey there Igofar, it has been some time since you posted this reply, but do you still have any of those filters, or did you wind up selling them? My bike is a 2010 which I just acquired in April.
thanks,
Mike

Catdriver said:

Hey there Igofar, it has been some time since you posted this reply, but do you still have any of those filters, or did you wind up selling them? My bike is a 2010 which I just acquired in April.
thanks,
Mike

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Hey Mike, I think I still have 2 or 3 left. They have already been de-greased and oiled, and are ready for installation.
I just don't know if I could sleep at night, knowing that I sold you a filter that let more dirt in your engine

I used a K&N air filter in my old K1100LT BMW and increased the MPG by about 8%. I sold it with 133,000 miles. I used it in my last 03 ST and sold it with 135,000 miles and I still have one in my 05 ST with no problems in site. It's still a coin toss. Just enjoy the ride.

hi ,

K& N air filter - definite yes for me... why ?

- cost effective over the period of the miles completed on the bike. ( If you have the cleaning & oil kit.)
- better throttle response / reaction. ( improvement yo can feel !)
- Million mile filter guarantee

I have fitted these to all my vehicles over the past 20 years and never had an issue to date. ( 12 cars , 20 different motorbikes.)

the dirt and sand in the Airbox is most probably the location you are in the world.... or what terrain you ride in.

I service my filter every 15 to 20 K miles

I have always used them , and always will.

regards

Tony

i personally have noticed that the k&n has a little better throttle response (very minor) but everything you do adds up the filter, minor jetting changes, synthetic oil, iridium plugs and new plug wires maybe a good set of coils and you end up with a better ride it is right that they dont filter as good though which is why i think they have better response

For the folks who are unlucky enough to live in California, keep one thing in mind, our bikes come from the factory very lean to begin with, and dropping in a K&N filter, will make them run even leaner! You may get popping and de-acceleration backfires etc.

Igofar said:

For the folks who are unlucky enough to live in California, keep one thing in mind, our bikes come from the factory very lean to begin with, and dropping in a K&N filter, will make them run even leaner! You may get popping and de-acceleration backfires etc.

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My 1100 has 107k miles with a K&N and the plugs look normal every time they're checked.