Air filter choices

[CyFi6]

Since I live in a VERY dusty climate, I am a little concerned about air filtration. After cleaning my engine bay, I literally find dust EVERYWHERE only a week later, it is crazy how dusty my area is. I have a 7mgte making 375 hp to the wheels and I am currently running an Apexi Dryflow air filter which supposedly filters pretty well according to some amateur testing I have seen online, though I don't know how accurate it really is. My question is how well does the stock air box and filter flow? Is it enough to support my engine without reducing any power when compared to an open element filter? I am sure that the stock unit does a better job of cleaning the air, but does that come at a cost?

I have been looking into oiled foam air filters as well. I am running speed density, so no AFM anymore. Oil shouldn't be an issue. I have actually read that a foam filter can outflow and out filter a paper element when used properly. Is this true? There is so much misinformation out there regarding filters it isn't even funny, so I thought I would come here and ask some of the experts. I do like the added sound of the open element filter, but of course that is not a primary concern, just would be nice to have. I remember most of the turbo spool noise was gone with an air box in place.

Anyways I appreciate any input on this.

 

[suprageezer]

Have you read any of Bob Is The Oil Guys write ups on air filters? He has some good info there.
http://www.bobistheoilguy.com/air-filtration-test/

 

[hvyman]

Aem dry flow and apexi filter the most.

IF you wanted you could make a box for it.

 

[Poodles]

Apexi is a paper filter (like OEM) just made a bit differently. Oiled foam is what the old HKS filters were, and they're pretty terrible...

 

[CyFi6]

I have read through some of the BITOG stuff but doesn't really help me a lot in my situation. That article is all testing on a stock Miata, but how will things change when a large increase in air volume is needed for higher horsepower? I have read over and over that apexi and aem dry flow filter the best, but the only evidence of this is an amateur test using some kind of black grit and a vacuum cleaner..

Apexi is paper like OEM yes, but are they created equally? The filter media might be much thinner, have larger "holes" for airflow etc. Same goes for the foam, not all foam filters are created equally. Foam filters are used a lot foroffroad motorcycles and such which are in very dusty environments, so that has to stand for something. Since I know that OEM filters filter very well, I am willing to run the stock setup, but I just don't know if it will cost me any performance.

 

[Poodles]

Foam filters break down, which is where the issue comes from. Most offroad motorcycles run a foam pre-filter over a gauss or paper filter.

 

[ubersonic]

The HKS foam filters get a very hard time mostly due to this test: http://mkiv.com/techarticles/filters_test/2/ which seems to have made it to every car forum on the whole internet, the actual test was done by a Japanese car mag in the late 1990's using a vacume cleaner to test filtration and a JZA70 Supra to test HP gains. The original test http://www.mkiv.com/techarticles/filters_test/1/ is now over a decade old and both HKS and Apexi have redesigned their filters since it was done (HKS now use a three foam system to prevent it coming apart, Apexi's intake is visibly different)

 

[CyFi6]

No other thoughts on the stock filter?

 

[hvyman]

My apexi still looks brand new on the inside. Can't say the same for the outside. My Afm also was clean the entire time. No dirt not oil. Also been over 4 years at least and well over 55k.
Can't say I havent seen about 50+ threads on afms getting replaced over and over with k&n. It's all in the name for that company.
Hks from my personal observation are crap. There thin and turn black quick. Even seen one fall apart and ruin a Afm.
No experience with a aem tho I'll prolly run one soon.

 

[jetjock]

It's a simple matter to check the stock box and filter with a manometer. If the drop is minimal (in my experience it will be) I would use that assuming your other plumbing is up to the task.

 

[CyFi6]

Well I don't have a manometer unfortunately.. How much vacuum on the inlet side of the turbo would you consider to be too much? From what I understand turbos are very sensitive to inlet restrictions. Also what do you mean by "assuming your other plumbing is up to the task"? Up to the task in what manner?