Any advantage to K and N air filter over stock?

[SpaceKing]

Tried to do a search on this but couldn't find anything . Does a K and N air filter provide better filtration and performance? IF you use one do you have to adjust anything else or is it simply put it in and ride?

thanks guys

Beno

[270]

No.

[ShovelStrokeEd]

They do provide a really keen decal you can put on your bike and impress all the kids down at the malt shop. Other than that, save your money. They do not filter as well as the stock paper element nor do they flow any more air. Not strictly true as the paper element has a much higher surface area so on a specific basis, the K&N might flow more. Tests run about 3 or 4 years ago using Saran Wrap on the stock paper filter showed no drop in HP with 75% of the stock filter blocked off so more flow is hardly needed.

 

Or, NO.

[Joe Frickin' Friday]

Tests run about 3 or 4 years ago using Saran Wrap on the stock paper filter showed no drop in HP with 75% of the stock filter blocked off so more flow is hardly needed.

 

In a similar vein: IIRC, someone did dyno runs with the air filter completely removed, and there was no measurable improvement in performance (as compared with having the stock paper filter in place).

 

Here's a piece I posted here on K&N a while back:

============================================================

The stock air filter does not cause any significant restriction to airflow; IOW, there's no performance advantage to be gained by using K&N. Their own flow bench testing (here, chart halfway down the page) shows that their filter flows more air than a comparable paper filter under the same pressure drop (see test conditions here), but a flow bench doesn't accurately reflect what's happening in an engine, where (for constant load and speed) each filter will have its own flow rate and pressure drop.

 

But without bothering to get into too much detail about that, you can see from their results that the K&N filter clearly is better. How much better?

 

Not much. Here's a rough estimate.

 

Take their test results I linked to above. Their round filter used in the test results there, E-1500, looks like it might be suitable for a 5.0 liter V8 engine. At 6000 RPM, a naturally-aspirated 5 liter engine is moving approximately 530 cubic feet per minute of air. Their chart showed the paper filter moved about that much air with a pressure drop of 1.5 inches of water; that's a mere 0.0542 psi. If you put their filter in and scale the flow (shown on the chart) and pressure drop back accordingly, the expected pressure drop would be about half of that, i.e. 0.0271 psi. So with manifold pressure increased by 0.0271 psi, the air density - and hence, power output - increase accordingly. Switching to a K&N filter would give you a net performance increase of:

 

0.0271/14.7 = 0.184 percent.

 

If you removed the filter element altogether, allowing the engine to breathe unfiltered air, you might expect an improvement in power output of approximately 0.37 percent. Note also that these improvements are only at conditions of maximum airflow; at lower RPM, the performance improvement is even smaller.

 

You'll notice that K&N have scrupulously avoided showing any comparisons of actual engine performance with paper filters vs. K&N filters. This is because they'd show you exactly what I've just described, i.e. a negligible improvement in performance. If you're a professional racer, certainly you'll take every competitive advantage you can get - especially if the product is free, and they're giving you sponsorship money on top of that - but you're not going to notice 0.18 percent when you're running Deal's Gap.

 

Regarding filtration quality, they brag about their superior filtration (efficiencies close to 99% at the relevant particle size), but the most they'll say about paper filters is that they've seen "some disposable paper air filters with an overall filtration efficiency as low as 93%." Again, if the K&N is so much better, why not present data on some of the leading aftermarket filter makers (as well as OEM)? More to the point, how often do modern engines fail because of inadequate air filtration? If my bike will make it to 250,000 miles on plain old Beemer paper air filters, then there's really nothing to be gained by investing additional money in improved filtration.

 

And FWIW, some here have complained about poor filtration by K&N (evidenced by an airbox caked with grime), and the hassle of re-oiling the filter element at the recommended intervals.

 

Lifetime cost? Can't find info for BMW filters, but Jeg's lists a K&N for my 2003 Nissan Maxima at $44, and I can probably buy a paper filter locally for $10. The change interval for the paper element is 30,000 miles which means the break-even point is 120,000 miles. The car came new with a paper filter, so I would wait until 30K miles before getting a K&N, and then have to run 120,000 miles after that to break even, a total of 150,000 miles. Am I gonna keep the car that long? Not likely. K&N filter for my car, then, wouldn't make economic sense; I'll wager the same is true for just about any vehicle out there.

 

Anyone know how much a K&N costs for an 1100RT?

[SpaceKing]

Wow! THAT was an answer. You guys are great, a shockingly thorough and complete answer! Your knowledge seems to be vast and unlimited. So now for the really big question: What do women REALLY want?

Thanks Mitch and Ed

[DiggerJim]

So now for the really big question: What do women REALLY want?

 

Guys who think like women or women built like guys.

 

They're emotive so they just want someone to listen. We're analytical so we just want to fix things. At best parallel tracks running to the horizon. Worse it's often rapidly diverging lines of thought.

 

Jim

[Gizmo]

Wow! THAT was an answer. You guys are great, a shockingly thorough and complete answer! Your knowledge seems to be vast and unlimited. So now for the really big question: What do women REALLY want?

Thanks Mitch and Ed

 

Freud spent 30 years trying to figure that one out and couldn't... so I doubt us mere mortals will fair any better.

[peterbulgar]

Answer to your second question:

Shoes.

 

peter '73 R75/5, '04 R1150RA, wife, two sisters, two daughters