Gentlemen,

I?ve started this thread in an effort to compile information in regards to the various performance ?drop-in? filters that are available on the market today for the S85 engine, in addition to providing some information in regards to air filters in general.

Let?s make an effort to keep this a purely technical thread.

In regards to ?Unknown? or missing data, I welcome fellow board members to chime in and help out where they can (ideally by providing measurements of the filter pleats in order to calculate surface area )- [in general] more filter element surface area = more airflow.

K&N

http://img251.imageshack.us/img251/6741/332350.jpg
Filter Element Type : Oiled Cotton Gauze
Filter Type: Flat Panel
Approximate Surface Area: Unknown
Filtration Efficiency (Average): Between 96-99%*
Air Flow Gains Over Stock (CFM): Unknown
Warranty : Signature 1 Million Mile / Limited Lifetime
Price: $80-$90/set
*Note - Claim as per K&N website on Filtration Efficiency
K&N Air Filter Efficiency Testing

BMC
http://img89.imageshack.us/img89/208...erbmce60m1.jpg
Filter Element Type: Oiled Cotton Gauze
Filter Type: Flat Panel
Approximate Surface Area: Unknown*
Filtration Efficiency (Average): Unknown
Air Flow Gains Over Stock (CFM): Unknown
Warranty: Unknown
Price: $160-$165 for the set
*Note- Judging purely from the appearance of this filter, it appears the surface area would most definitely be greater than that of the K&N filter.

AFE Pro-5R

http://www.jlevistreetwerks.com/imag...%20A%20400.jpg
Filter Element Type: Oiled Multi-Layer Cotton Gauze
Filter Type: Inverted
Approximate Surface Area: 224 In. Squared
Filtration Efficiency (Average): 98.6%
Air Flow Gains Over Stock (CFM): 110 CFM (25%)
AFE Bench Air Flow Test on S85 Pro-5R Performance Filter
http://www.jlevistreetwerks.com/imag...FLOW%20400.jpg
Warranty: Limited Lifetime
Price - $150-$160 for the set

AFE Pro-Dry S

http://www.jlevistreetwerks.com/imag...%20A%20401.jpg
Filter Element Type: Dual Layer Synthetic Media Gauze
Filter Type: Inverted
Approximate Surface Area: 224 In. Squared
Filtration Efficiency (Average) 99.2%
Air Flow Gains Over Stock (CFM) : 99 CFM (22.5%)*
Warranty: Limited Lifetime
Price - $150-$160 for the set
*Note - Values calculated by aFe claims that (AVG) 10% more flow is realized on the P5R (Oiled) filter element versus the PDS (Dry) filter element.


Basic Comparison of common filter medias (paper, foam and gauze).


Paper (OEM)

http://img256.imageshack.us/img256/135/paperp.png
Tightly compressed cellulose fibers bonded together provide very small pores. Dust is captured on the surface as air flows through these pores. Restriction increases as dust accumulates on the surface. Very good filtration but relatively poor airflow. Very limited service life, not reusuable.

Foam (ie: ITG)

http://img524.imageshack.us/img524/6379/foam.png
Synthetic foam provides larger pores than paper and compensates with thicker materials. Often utilizes a tackifier to capture dust. Restriction increases as dust accumulates on the surface. Good airflow until dirt builds up on the surface. Limited service life due to no depth loading. Washable but difficult to clean.

Oiled Cotton Gauze (K&N, AFE P5R, BMC)
Cotton gauze media provides large pores with microfibers extending into these pores. Multiple layers of gauze increases filtration as they overlap. Oil is generally used as a tackifier, lubricating the microfibers and as a result - captures dust particles as they come in contact. Retains excellent airflow thruout the service cycle with improving filtration efficiency as more dust accumulates. Washable, easy to clean and reoil/service.
http://img706.imageshack.us/img706/4088/gauze.png
Dry Synthetic Gauze (AEM Dryflow, AFE Pro-Dry S)
Utilizes oil free media with several layers of different porosity synthetic materials. Requires no oiling and dries quicker because it retains little moisture. Retains excellent filtration efficiency thruout the service cycle. Airflow generally remains excellent until huge amounts of dust accumulates towards the end of service cycle. Washable, easy to clean and requires no re-oiling or re-charge kits (only soap & water).

Advantages of Inverted Filter Type vs. Flat Panel
Inverted filters are designed to fit into the same stock airbox that the standard flat panel filter goes into, but utilizes an inverted "cone type" design which allows for more filter media surface area to be fitted into the OEM airbox when compared to flat panel type filters. This, in short, translates to increased air flow in comparison to flat panel type filters.

I will periodically maintain this thread with updates as they come in as new information is gathered on the specifics.

Comments, concerns, questions, etc. are welcome and appreciated. :thumbsup:

Great Cal! Good thread. I wish someone would do a PROPER dyno for K&N vs BMC vs AFE Pro-5R va AFE Pro-Dry S. The AFE filters does look pretty good but not sure if it works as it says.

+1.... and when you coming back from the vacation Johnny?

If these give gains I'm in all they way!

I've seen dynos in the past that showed minimal to no gains for almost every air filter in the market. Until someone actually puts some proof out there I'm gonna stay sketchy about these and keep my money in my wallet.

My question is, is it true that you can "ram" air easier into a flat panel filter than you can into any other designs like inverted, conical or oval filters?

Cal, did you post this on M5Board? My concern is that there are hardly any technical pros/tuners here to comment and provide factual info. I think Eloy and Gabe from RPI are the only two knowledgeable people here that contribute info to this forum but it'd be nice to get varying opinions.

That is a good question, and should be looked into. In theory, the (supposedly) greater surface area of the inverted type filters should produce more air flow in any situation (I say supposedly as there is no surface area data on the flat panel type filters...yet). In any case, without sufficient real world testing....this would all be pure conjecture.

As for M5Board, yes I did post on there...but unfortunately it was moved into the vendors section... :think:

How to measure a filter for surface area.

1. Pleat Depth

http://img251.imageshack.us/img251/1...kedfilter1.jpg
*Note - About .1" of "dead space" on this particular ruler
http://img190.imageshack.us/img190/9...kedfilter2.jpg
AFE Filter: Approximately 0.5"

2. Height
http://img252.imageshack.us/img252/6...kedfilter0.jpg
Measure height of the pleats.
AFE Filter : Approximately 3.5"

3. Number of pleats
http://img29.imageshack.us/img29/559...kedfilter4.jpg
AFE Filter: 64 pleats

To calculate surface area:
Multiply pleat depth measurement by 2 (each pleat has two sides).
0.5 X 2 = 1
Multiply above number by number of pleats & height
1 X 64 X 3.5 = 224 Inches Squared

http://img269.imageshack.us/img269/4...kedfilter3.jpg

I encourage board members to chime in with these measurements on their own preferred brand of performance filter :thumbsup:

I would love to get more info on this. I just purchased a K&N Filter since I have a longstanding history of using them starting with motorcycles and then moving along with many of my former cars. K&N has always proved to be a very efficient intake filter. I do however acknowledge that the BMC filter does appear to have a slightly larger surface area of filter material and less plastic trim bordering the filtered area, and the AFE, well that's just a totally different ball game now...Very curious how this would work, but for the time being I am going with what I know based on past experience.

Well here is an update. The picture in the starter thread above shows a very restricted K&N filter with little filter surface area.
The K&N Filter I just received and installed in 30 seconds had a very different look. Much more surface area of filter paper...very similar to the BMC filter.
See below:
http://img.photobucket.com/albums/v6...tualFilter.jpg

http://img.photobucket.com/albums/v6...NFilterBox.jpg

http://img.photobucket.com/albums/v6...ilterlabel.jpg

Just thought I'd share.