AEM dryflow, intake coated in fine dirt

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Jan 5, 2021
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I'm running a 4" inlet conical AEM dryflow on the custom single turbo system on my Supra for the past 3,000 miles or so and I found a light coating of very fine dirt in the entire intake tract from the filter to the manifold. It's enough that I immediately noticed it when I pulled the intercooler pipes apart (upgrading the intercooler again). I can swipe my finger in a pipe and my finger tip is dirty. Everything was brand new and completely clean when I started using this filter, no intake or boost leaks or any other way for dirt to get in other than through the filter media. Back on the stock turbos I was running a much smaller oiled k&n and never saw anything in the pipes like this. The only other factor that could be at play here is that the filter sits behind the headlight opening and is directly exposed to rain. I try not to drive the car in rain, but it did happen a few times. Could water be washing the captured dirt out of the media into the inside with this type of filter?

I've now noticed that they sell hydroshields for them and will be getting one but I'm curious if anyone else has experienced similar.
 
Open intake with K&N cone filter on my Golf is squeaky clean inside pipe and turbo inlet. On a non-oiled filter the rain thought seems reasonable. I take it your headlight has been removed for direct flow to the intake?
 
most of those high flow performance filters pass dust
Yes they will certainly not filter at the same efficiency as a standard paper filter but should not be seeing what he is. I run them on all my cars with zero drama and clean intake tracks the "white glove test". Something else is going on.
 
depends if you live in a high dust or dirt particle environment, if I was a city or suburbia driver I'd be less inclined to worry
And that's me....suburban east coast. UOAs always look good.
 
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me too, I wouldn't worry too much, I wouldn't use one if I lived in a dusty desert type enviro I could see where that would be a issue
Neither would I or just have to monitor it and likely clean it more frequently.
 
To be clear, this is a dry filter, not an oiled one.

I do live where there's a lot of agricultural dust and dust from coal mining. They also gravel the roads heavily in winter and that stays around all year making dust. I park the car in a gravel lot when I take it to work. So I would say there's probably more dust than most places.

I'm a tech by trade and I've a lot of intake pipes apart over the years from vehicles being used in this area and usually only see this much dust in an intake when the filter box when there was a sealing issue.

This is just a basic AEM brute force 6x9" dry cone filter on a short plain 4" aluminum pipe with a silicone coupler on the turbo inlet. Everything is clamped properly. I can't imagine where there could be a leak. I checked the filter media itself for any defects (not glued, ripped, etc). The rest of the turbo system was smoke tested and is leak free.

It's behind the headlight in the engine bay but it's a pop-up light and when the pop up is open the rain can blow almost directly on the filter. After driving in the rain the filter is wet. I can't really do much about it other than put a water repellent wrap on the filter. There's nowhere to relocate it to.

I just remembered that I had another AEM dryflow before, on my Mazdaspeed3 about 12 years ago. I don't remember there being dust in the intake like this. On that car the filter was in the front bumper opening where there was a lot of road dirt but the filter never got wet. That AEM dry filter was different looking than this one though, it was white and fluffy. This new one is sort of stiff flat grey media. Different media I guess? I wonder why they changed it.

I guess I will just get the hydroshield wrap for it and clean out everything and see how it is after a few thousand miles again. I guess I will run a UOA and see what that says too.
 
Yes I realize it's a dry-flow, but folks just lump them all in as the same around here for being higher flow/less filtering. I run K&N oiled in all my cars but tons of guys run the AEM drys with good luck. I'm going with the wet issue - the rain cover may well sort is out.
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theres tradeoffs with high flow filters, #1 is more dust gets by the filters media, big question is how much dust are you willing to accept when it comes to your driving conditions, or if that amount will eventually do harm to the vehicle.
 
I live in the SoCal high desert and have 3 vehicles on AEM Dry Flows. My '18 Honda Civic and '19 Honda Ridgeline are on factory intake drop in style filters, and my 2005 Nissan Titan has a Volant CAI with a cone filter. No issues whatsoever with any of them, and the Titan is my work truck and lives a very tough life on job sites and has over 170k on the odometer with over 100k of that being on the Dry Flow.

All 3 intake tracts are always pristine when I clean them once a year.
 
Revisiting this old thread. I now have a re-branded AEM Dry Flow filter (as far as I can tell) for a new intake I am running vs. the older intake with a K&N oiled filter. Now I am seeing fine dust/pollen in my intake tube. I wonder if the idea of rain presented here is the issue? I ordered a new filter just to be sure but if it doesn't solve it, I'll find a universal fit K&N oiled that is close in size and run it as until now I've never seen dust in my intake on any vehicle I've owned running a K&N. The intake is a closed system but is directly open to the front of the grille so the rain hypothesis *could* be a variable here. Where the oiled filters would likely resist water ingress to me more. I could also try running one of the "water socks" over it, they are cheap on Amazon.
 
Update. Went ahead and ordered a new Unitronic filter for my intake (looks to be a re-branded AEM). The other one is in the trash. More pollen dust in intake tube after a thorough cleaning...had to be a bad filter as these filters should be more than adequate here based on what I've seen of my K&Ns over the years...never seen dust in my intake...ever. I'll check in a few weeks. If that doesn't do it, I can probably find a K&N that fits but I really like these as they have a velocity stack in the outlet and have a lip that fits flush to the intake tube.

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