DIY: AEM Dryflow air filter cleaning! It could add a horsepower!
Whats better than a slight performance gain off your air filter? One that is easily cleaned and reusable throughout the lifetime of your vehicle! Seeing as my two Subarus won’t see any further gains from a aftermarket intake I wanted to find a reusable air filter. My STi came equipped with a K&N filter but as we know the oiled filter often leave oil particles on the MAF sensor, which can cause incorrect MAF readings that won’t allow your engine to run as optimally.
With this said, I found AEMs Dryflow filters my savior, the only downside was that they did not offer any for my Forester or STI. So with a bit of cross referencing I found that many filters used in Nissan vehicles are also used in Subaru models. Therefore they will/should fit given their similar dimensions. Last year I noticed they did decide to release Subaru specific filters for my 06 Forester XT and 05 STi, I have purchased one to see how they differ.
Now let us get down to business… we need that one horsepower back! If you would like you can use a flat head screwdriver to help loosen the intake hose and to help the release the clips holding the air box together. Finger can be your back up if this method didn’t work or you have misplaced all your screwdrivers when doing other projects and failed to return them.
First we will remove your air filter. For all three of the Subarus in my stables I can use my hand to release the clips that sandwich the air box together.
With the air filter removed we can spray it down with the Aem dryflow spray. You will only need to spray the filtering side of the filter. i.e the side that has all the dirt, bugs, grass, etc in it.
Now allow it to sit and soak in.
Next we will take the filter to our source of water and spraying through the top side of the filter we will help loosen up the rest of the stuck debris within the filter pleats.
The next step is based upon how fast or slow you would like your filter to dry. In slow mode we will just set the filter out for about 24 hours and it should be dry. You can check it by lightly tapping it on the ground and looking for water droplets. Now you will wave it up and down very quickly to make sure there is no stored away water, the last thing you need is your engine ingesting water and causing engine problems. If it checks out to be dry you will be finished.
If you are looking for a faster approach you can use compressed air to help push the water out. I recommend spraying the air through the top side, this will help anything deeply lodged items to exit your filter. Once you have checked it again with the above steps for trapped water. You can put it back in and go on your way.
Remember your engine is a giant glorified air pump and any left over water will be sucked in with much force. So make sure it is absolutely dry before reinstalling it. Irreversible engine damage can happen if your engine attempts to consume water.
Congratulations! You have completed your air filter cleaning and can go on for another 15k miles or 1 year, whichever comes first! Perhaps your one horsepower has also returned.. maybe even 1.5 hps or more! Just another maintenance step to helping your engine last long and run smoothly.