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Old 04-17-2012, 09:01 AM   #12256
shadygrady
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Quote:
Originally Posted by helotaxi
What's the actual filter surface area? IOW if you were to remove the filter element from the shell and flatten it out, which is bigger? It looks like the pleats in the K&N are closer spaced than the other one. If neither is actually restricting airflow into the intake and the filter area is the same, any difference is negligible.
With all things being the same (porosity of the filter material and surface area of the filter element as its flattened out), it would make sense to me that if one filter has the filter element squeezed into a tighter space (which is evident on the K&N) then that filter would have a more restricted flow than the other. I'm no expert but it seems logical to me.

I'm sure there is a lot more to these filters than just what meets the eye.
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Old 04-17-2012, 09:29 AM   #12257
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Quote:
Originally Posted by shadygrady View Post
With all things being the same (porosity of the filter material and surface area of the filter element as its flattened out), it would make sense to me that if one filter has the filter element squeezed into a tighter space (which is evident on the K&N) then that filter would have a more restricted flow than the other. I'm no expert but it seems logical to me.

I'm sure there is a lot more to these filters than just what meets the eye.
I'm not sure you can draw that conclusion based mainly on the fact that K&N filters are shite. I know, it's like oil and what people swear by but I'll never have a K&N filter on any of my bikes. In fact, my Speed Triple had one fitted by the PO and I removed it.
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Old 04-17-2012, 09:42 AM   #12258
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Originally Posted by Mercury264 View Post
I know, it's like oil and what people swear by but I'll never have a K&N filter on any of my bikes
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Old 04-17-2012, 09:48 AM   #12259
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Quote:
Originally Posted by Mercury264 View Post
I'm not sure you can draw that conclusion based mainly on the fact that K&N filters are shite. I know, it's like oil and what people swear by but I'll never have a K&N filter on any of my bikes. In fact, my Speed Triple had one fitted by the PO and I removed it.
I'd agree, with the disclaimer that I'd be OK running a K&N on a street bike in a non dusty environment. I ran one on my cruiser for 4 years and 40,000kms with no ill effects, but I'd never run one on my DR or any bike I rode on gravel roads etc.
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Old 04-17-2012, 09:53 AM   #12260
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Quote:
Originally Posted by Mercury264 View Post
I'm not sure you can draw that conclusion based mainly on the fact that K&N filters are shite. I know, it's like oil and what people swear by but I'll never have a K&N filter on any of my bikes. In fact, my Speed Triple had one fitted by the PO and I removed it.
I apologize! I certainly wasn't trying to draw any overall conclusions. I just wanted to address the comment about the filter surface area vs filter element surface area. The original question was asking about one filter having a smaller/larger surface area than the other (K&N is smaller) and the discussion led to the surface area of the element (??). Too many variables to conclude anything with a visual inspection. Real testing is the only answer. Everything else is speculation! I've heard the same thing that Blacktiger mentioned about the better air flow rate of the DNA

shadygrady screwed with this post 04-17-2012 at 10:02 AM
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Old 04-17-2012, 09:53 AM   #12261
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Originally Posted by bross View Post
I'd agree, with the disclaimer that I'd be OK running a K&N on a street bike in a non dusty environment. I ran one on my cruiser for 4 years and 40,000kms with no ill effects, but I'd never run one on my DR or any bike I rode on gravel roads etc.
Quite and that's why I also have the Uniflow pre-filter fitted.
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Old 04-17-2012, 10:02 AM   #12262
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Quite and that's why I also have the Uniflow pre-filter fitted.
To me that seems counter-intuitive - unless I'm mis-undersanding. You put on a K&N and since it's flow more air (and hence, more dirt/dust) you put on a pre-filter -do I have that right ?

If so...that doesn't make a whole lot of sense old bean
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Old 04-17-2012, 11:41 AM   #12263
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Except that if he was going to uni filter it anyways, the K&N kinda makes up for the added uni restriction.
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Old 04-17-2012, 12:05 PM   #12264
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I guess HT has finally released the guards. Good to see. Any fitment issues?
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Old 04-17-2012, 12:59 PM   #12265
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Originally Posted by blacktiger View Post
Speculation.
According to their respective web sites the DNA flows more air/minute than the K&N which in turn flows more than the stock filter.
My point was that if the engine draws less than either is capable of flowing, then which one CAN flow the most is moot. If the possible CFM of the filter is less than that of the engine, the engine, not the filter, is the limiting factor.

Figure 800cc x 5,000rpm (redline RPM/2 for a 4-stroke) = 4,000,000cc/m Convert that to CFM and you get 141.25cfm. According to K&N (the "more restrictive" of the two) their filter will flow 176cfm. The air filter is not the limiting factor. It is capable of flowing more air than the engine is capable of drawing at redline.

If you judge filtration efficiency by airflow alone, then both are worse than stock and neither should be considered. There's a lot more to it.
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Old 04-17-2012, 02:03 PM   #12266
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Originally Posted by helotaxi View Post
My point was that if the engine draws less than either is capable of flowing, then which one CAN flow the most is moot. If the possible CFM of the filter is less than that of the engine, the engine, not the filter, is the limiting factor.

Figure 800cc x 5,000rpm (redline RPM/2 for a 4-stroke) = 4,000,000cc/m Convert that to CFM and you get 141.25cfm. According to K&N (the "more restrictive" of the two) their filter will flow 176cfm. The air filter is not the limiting factor. It is capable of flowing more air than the engine is capable of drawing at redline.
Wouldn't the exhaust efficiency need to be factored in somehow?
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Old 04-17-2012, 02:17 PM   #12267
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Quote:
Originally Posted by Mercury264 View Post
To me that seems counter-intuitive - unless I'm mis-undersanding. You put on a K&N and since it's flow more air (and hence, more dirt/dust) you put on a pre-filter -do I have that right ?

If so...that doesn't make a whole lot of sense old bean
Well, firstly you need to read my post properly. I put in a DNA filter.
Quote:
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Firstly I don't think you mean Keihin. Perhaps K&N??

So, at the moment your choice is, AFAIK, between K&N and DNA. I have the DNA and it's too early to tell how long it's going to last or how it's working but it's in there and nothing has broken yet.
The reasoning is that the air filter is buried under the tank and takes an hour to get at. So I put a low maintenance filter in there and put the pre-filter to take out the worst of the dirt. I never said, wrote or quoted that it was for performance. For me it's purely for ease of maintenance.
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Old 04-17-2012, 02:36 PM   #12268
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I guess HT has finally released the guards. Good to see. Any fitment issues?
Not sure if they have or not. I was able to get a prototype from them. No real fitment issues. They are a little difficult to install. You need two people. But they are very stout!!!
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Old 04-17-2012, 04:05 PM   #12269
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Quote:
Originally Posted by blacktiger View Post
Well, firstly you need to read my post properly. I put in a DNA filter.


The reasoning is that the air filter is buried under the tank and takes an hour to get at. So I put a low maintenance filter in there and put the pre-filter to take out the worst of the dirt. I never said, wrote or quoted that it was for performance. For me it's purely for ease of maintenance.
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Old 04-17-2012, 05:21 PM   #12270
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Originally Posted by shadygrady View Post
Wouldn't the exhaust efficiency need to be factored in somehow?
In a perfect world you could gain a little extra effective flow from head velocity and a little precompression, but that also assumes perfect exhaust scavenge. For the filter to become the limiting factor, you're talking 20% increase in efficiency from exhaust tuning. That would be pretty impressive.
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