I've been doing some research on the best available drop-in reusable air filters on the market and it seems like AFE might be the winner. Apparently they have a pretty big following with the BMW and diesel truck folks when it comes to their intake kits and filters. AFE claims an increase in flow without a compromise in filtering efficiency, which is what I've been looking for in a reusable filter. Cosworth's filters were also on the table, but in the end more folks have used the AFE. If Amsoil made filters for our cars, I would've been looking at those too. Sorry K&N, but not a fan.

I sprung for a purchase of the AFE Pro Dry S filter set (didn't pay the retail price of course) to replace my HKS SuperHybrid filters. I should've bought the AFEs instead of the HKS in the first place due to some serious doubts of their foam filtering performance. Currently I'm back on the OE papers. I've tried to get some answers directly from HKS concerning their filtration testing, but basically got a response saying you're going to give up filtering for flow and sorry we don't have documentation, uggh! Not very good customer support IMHO.

The folks over on Bob Is The Oil Guy have done numerous oil analysis with these filters and got some nice results with pretty low silicon ppm that got better with mileage. I'm not expecting any huge gains in terms of performance, but just a safe filter that I can wash out and keep for a while.


Description from their site:
"This performance air filter outflows the factory air filter by 16%. Constructed with 100% polyurethane on all four sides, this high flow "oil-free" OE replacement performance filter will outflow stock paper filter for improved horsepower and torque. Two layers of progressively finer mesh synthetic media provide maximum convenience and easy maintenance. Washable and reusable for multiple cleaning cycles, the tall open evenly spaced pleats provide excellent dust holding capacity for longer service cycle between cleanings. Integrated urethane bump seal insures tight, no leak seal over the life of the filter."

The dual filter kit part number 31-10196
Single filter 31-10173

They also offer the Pro 5 R filter, but these are oiled cotton gauze media which I'm going to avoid.

 

I've never doubted that they flow more air. But do they have any documentation of filtration efficiency of these vs the efficiency of the stock paper filters? I haven't been able to find any credible data on any filters regarding filtration efficiency. It makes me a bit cautious. My thinking is that if they truly did have equal or better filtration and had solid test data to back it up, I'm surprised it's not used in their marketing.

 

^ agree. With no filter i let in 100% more air then before, but i need filtration. Carful imo

 

I agree with your concerns over test documentation. Their site says 99.2% filtering efficiency, but how are they coming up with this number that's the question. I have an email into AFE asking about documentation and how they do their filtration testing.

 

I didn't visit their site so I was wondering if they even quantified it or just claimed to be better than stock. A claim of 99.2% at least puts a number out there for comparison. It would be great to know other filter's efficiency based on the exact same criteria but that's just a fantasy to get a true objective test.

 

For what it's worth, Cosworth says their filters are at 98% - *ISO5011:200 Fine Dust Test and offer a 10% reduced restriction over OE filters.

 

Did some more research about air filter testing, pretty interesting. Southwest Research Institute apparently does quite a bit of independent lab testing for companies like K&N, AEM, Amsoil, etc on their filter products.

I found this test result report - http://www.autohifidiszkont.hu/bmw-t...szuroteszt.pdf

Also from AEM's website: We use ISO 5011:2000 with ISO “A-2 Fine Dust" as the contaminant. Southwest Research Institute performs the testing and determines flow rate criteria based on the average flow requirements of a typical engine on which the filter to be tested will be used. The concentration of the contaminant introduced into the air stream is significantly higher than what would be encountered in normal use in order to perform the test in a reasonable time. Typically, 2 flow rates are used for testing. 160 CFM is used for smaller displacement engines. 240 CFM is used for larger displacement engines.

 

Continuing the research fun...

Found this post on a BMW forum where a distributor toured the AFE Factory. Looks like a very impressive facility with their own filtration and flow testing equipment. The other thing that was pretty neat is they make all TRD (Toyota Racing Development) air filters.

Jlevi SW's Full Tour of aFe's Factory & Warehouse: Photos and Videos! - BMW 3-Series (E90 E92) Forum - E90Post.com

 

Thanks for all the great info Adam. Great thread with useful stuff in it!

 

Checking out some of the Japanese tuner sites and noticed that Trust/Greddy has an air filter made by AFE - ƒgƒ‰ƒXƒg ƒGƒAƒNƒŠ�[ƒi�[ GRACER AIRINX B Type Neat!

 

These AFE should be showing up on my doorstep tomorrow.

 

The filters arrived today in a nice AFE box. Upon inspection, the filters are very nicely made with black rubber all around, these should fit into the stock air box well. I haven't had a chance to install them yet since the car is in the garage.

In the box was also some cleaning instructions that provides 3 different options for cleaning the filters. 1) Tap Clean - tap the filter on a hard surface to restore up to 85% of original airflow. 2) Vacuum Clean - vacuum the filter to restore up to 96%. 3) Wash clean using regular water or mild soap/detergent and let air dry for a couple of hours - this is 100%. These are dry medium so no oiling required.

 

So do the drop-ins give produced some of the sound associated with HAI without the tubing?

 

I've had another set of drop-ins (HKS) and they didn't produce any different intake sound, so I doubt the AFE will change that.

 

I have an AFE intake on my 08 duramax silverado. I also know a handful of guys who also use their intakes in other diesel trucks. The quality I've seen from them is top notch the filters easily wash out and are like new again and all their intake tubing fits perfectly. I didn't know they made a replacement for the G but I'm definitely gonna order one now thanks!