Hey Guys,

I've read a bunch of posts on this topic, but never one that answers "Which filter is better?".

Since both are made out of cotton and use the same filtering principals, the only difference between them would be the number/size of the pleats. Of course, larger pleats and/or a larger NUMBER of pleats will lead to a greater surface area for the filter and thus more airflow. So since this is an item that probably can't be tested on the dyno reliably. I guess the number of pleats is the only factor that can decide which filter flows better.

A BMC filter will cost me $122 + $10 shipping = $132.
A K&N filter will cost me $79 at a local shop.

I don't mind paying more for the BMC if it's a better filter, but the question is, IS IT a better filter? Seeing as the BMC is 67% more expensive for me vs. a K&N filter...I'm curious to hear your opinions!!!

Thanks,
KJ

 

The K&N is overoiled (thanks dock) the BMC is not...end of story....
The K&N has been known to cause problems because the oil gets to the Mass Airflow Sensor... We have never had a problem with the BMC, however I have seen problems with the BMC...
As for which one performs better...you would never notice a difference between the 2....
Evan (I have had both)

 

FIlters are simple, but not that simple. Surface area is important,
but flow to the surface is also important. Imagine that you took
a K&N or BMC apart, and compressed the pleats so tightly that
you could fit two elements into the one housing. Theoretically
you have twice the surface area, but the flow path would be
very difficult.
Flow *can* be tested easily for filters. I also care about
how well (and for how long) they capture harmful particles.
I agree with you that it would be hard to dyno test the affect
of filters. I hear that folks who have tried, have found that the
difference is now more than 2hp between stock and K&N etc,
which is absolutely imperceptable.
Until I could see documents about the *filtering* efficiency
of the different filters (percentage of particles over the filter life),
I suspect this is one area where you can 'just be happy' and
stick with the stock filter.
Joe

 

All of the BMC filters I've bought have been pre-oiled.

 

I appologize, I mistyped should say OVEROILED
Evan

 

Keep what you have. Stock is just fine.

 

I think this surface area hypothesis is crap...More pleats yields more surface area, but that does not mean more air getting in faster. Quite the contrary...if it was just flat and had no pleats...less surface area, you would probably get more air in quicker since it is less restricted going through less material given the same outside filter dimensions L x w. More pleats will yield better filtering of the particles out before the air exits however. Simple common sense.

 

I would have to disagree. I think the "filtering of the particles" is dependent on the filter material used...not on the number of pleats. The material will filter as good as it can, and will always allow a certain amount of air past it. With less pleats, the filtering performance will remain unchanged, but the air flow will be much lower.

Also, a greater number of pleats will allow more "passages" for the air to get in. In anything scientific, if you want something to react with something else faster, you always increase the surface area EXPOSED to allow a greater effect.

This is why many cars switch to conical air filters vs. flat panel filters when using aftermarket intakes. The conical air filters provide a greater surface area but take up less volume in the engine bay. Unfortunately, they are also exposed to the elements (which includes heat from the engine).

- KJ

 

Well, sorry, no. Surface area (modulo it's getting adequate flow)
is testably, logically, linearly connected to lowered resistance to
flow. For example, two plain sheet filters as you describe will
flow twice as much for a give pressure differential as one would.
A regular filter that folds twice the surface area into the box
that passes the air will flow more than the one flat sheet, as
long as the extra surface area isn't folded over so tightly that
air doesn't get to it. Also, surface area provides dirt capacity.
A lower-surface area filter will clog sooner than one with more
surface area.
Air, like any other fluid, will typically pass through the path
of least resistence, so it will only go through one width of the
filter fabric.
I suspect that oiled fiters decrease in their filtering capability
as the surfaces get covered in dust, at which point it may pass
more dirt. Paper elements will tend to clog more, and will never
pass more dirt (ie: they are better for the engine long-term),
but their resistance will climb, lowering performance...
I'll go with the latter, and just change the paper frequently.
Joe

 

yeah, well... E=mc2

 

Hey Joe, I'm glad we agree

What you said about the paper filter clogging more is absolutely true. However, from what I've heard, oiled filters actually filter better when they get dirty. The reason they require the sticky oil is because their material is much more porous than a paper filter.

When an oiled filter is new or freshly oiled, there are still gaps that allow more dust through than a paper filter. But I think as dust gets trapped in the filter or sticks to the oil, it in-turn helps trap more dust since the holes are now getting clogged.

- KJ

 

I recently changed my stock paper filter to another oem paper one at 12,000 miles. Old filter looked " dusty " but not dirty. Interesting thing is the engine ran differently and idled less smoothly for first 100 miles, then the ECU relearned and ran just fine. Amazing how sensitive the car's sensors are to even this small a change .

 

Hi KJ.
I don't buy it about the oiled ones. If we assume that when
fresh, there are gaps through which dirt can pass, then it
is not filtering well when fresh. If it relies on those gaps
filling when the filter collects more dirt on the oil, then these
are just like the paper filters, that they will provide more
resistance (and less power) too when dirty.
MKW, what brand of paper filter was it? Yes, our cars are
sensitive to changes, but my concern is that the new filter might
also be flowing better because it's filtering less. If we'd heard
more stories about the same adjustment being felt when going
from an old stock filter to a new stock filter, then we'd be sure
about the cause.

 

I'm still not convinced...Cone filters use much less material than a panel filter. If you took the filter panel and wrapped it into a cone shape, the cone would be much bigger than the manufactured cones used in cup cars...There is less filter surface area in a cup car cone than a panel....and guess what, it flows more air,,,

 

It was old stock paper air filter changed to same new .