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Old 11-15-2008, 06:45 PM   #1
Scooby Newbie
Member#: 93785
Join Date: Aug 2005
Location: central NJ
2005 STI

Default Lab results of pressure drops for dirty AEM air filters

Figure 1 page 3
Pressure Drop (inches H20) versus Dust Retained (grams)




It occurs to me that AEM Dry Flow air filter users (myself included) can also use this chart to estimate their pressure drop on their dirty filter if it's too inconvenient to measure pressure drop directly. You can just weigh your filter before and after you clean it (and wait for it to dry before weighing).

Thank you AEM for testing your Dryflow filter at the independent lab, and also publishing the results!!!

Now notice that this is also very good information for the owners, not just the prospective purchasers.

FWIW Here's what I learned from this chart: If my air filter weight loss is greater than 60 grams after the next cleaning I give it, I am going to be cleaning it more often. Minimal pressure drops for me, if I can help it!

("Pressure drop" is another word for "flow restriction" if you are new. Pressure drops are baaaaad. Zero drop is gooood for car performance. You do like performance, don't you?)

Would be nice if more manufacturers also got their equipment tested like AEM did.

By the way, I am also sending props out to APS / Air Power Systems in Australia for testing (albeit themselves) and posting both their lab-measured pressure drops and sound pressure levels for their exhaust systems. Their pressure testing results is a big reason why I bought an APS exhaust system even though it was pretty expensive, rather than buying an exhaust from other companies. I have the R2 turbo-back, and it totally rocks. 88dba at the tip but same exact pressure drop as the R1 when cat is present, so R2 is quieter, and less likely to attract some fuzz, yet is every bit as powerful on the dyno (344 w/stock turbo, thanks to Hill @ Agile) as R1 on this application.

Extra kudos to AEM on the integrity meter for forking out the money to get the test done, by a different company (SWRI) rather than doing the test themselves.

SWRI is the company that AEM contracted to do the testing. SWRI also has some other interesting automotive testing articles on their web site also.

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Old 11-15-2008, 06:57 PM   #2
Scooby Newbie
Member#: 93785
Join Date: Aug 2005
Location: central NJ
2005 STI

Default 20 grams of dust in AEM filter causes 1 inch pressure drop

This other chart shows that it only takes 20 grams of dust to cause 1 inch pressure drop.


60 grams of dust is what caused 1 inch in the chart which I referenced in my previous post.


OK I guess 20 grams of dirt loss after cleaning (versus dirty weight) is my new target air filter cleaning interval....
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Old 04-06-2009, 01:56 AM   #3
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Join Date: Aug 2008
Chapter/Region: Tri-State
Location: NJ
2004 WRX Sedan


So did you weight your filter yet? I'm interested to see how much dust you would pick up after 10k miles. 60 grams seems like a lot of dust.
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Old 05-08-2010, 04:01 PM   #4
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Join Date: Jul 2009

does it matter if you clean the filter w water or w/ the solution? I bought the solution but its on back order. pm me for response thanks
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Old 08-01-2010, 04:01 PM   #5
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Originally Posted by mrcoder View Post

60 grams of dust is what caused 1 inch in the chart which I referenced in my previous post.
Bump from the dead, I know. But I'm researching air filters.

Just to put things into perspective for those that get super excited over numbers but have no idea what UNITS those numbers are in...

1 inch (of H20) pressure drop due to a reported 60 (or 20, whatever) grams of dust correlates to a .036 psi of resistance. Yeah, that's zero point ZERO three six pounds per square inch... That means your turbo has to work 0.036 psi harder... OH NOES! THE WORLD WILL END!
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