Effect Of OEM Style And Aftermarket Performance Air Filters On Vehicle Parameters

fmorelli

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2016 study. It's worth a 5 minute read, and one wants to read the whole thing as the net of the tests in the latter half of the paper show what one wants to know. PDF of the paper is attached.

Filippo
 

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Torgus

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Basically they dont do much in stock applications.

My thoughts:
At the end of the day if you let more air in you are going to let more particulates in assuming the filter areas are equal. Which is common sense.

Putting a drop in k&n on your accord is not going to net any hp worth noticing, which I think we all knew.

DCI do make more hp on a tune on an n54 because you need more air and the stock filter is a slight restriction because it was not designed to flow more than was needed.
 

Rob09msport

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These tests were at stock power but still show highest efficiency with the k and n but I don't like the low level of filtration. I have been wanting to put pro 5 dry filters on my pr inlets but I am waiting until I figure out what I am doing to stop the horrible heat soak hot side inlets cause first
 

fmorelli

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Compared to a paper OEM filter:
  • K&N: higher pressure drop, both new and with filter clogged.
  • K&N: higher resistance to air flow, both new and with filter clogged.
  • Load test: differences found to be negligible in both new & clogged.
  • K&N: 0.1 second faster acceleration vs paper, new & clogged.
  • Here's a killer: K&N has half the filtering efficiency of a paper filter.
Not exactly a sterling "upgrade".

Filippo
 
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fmorelli

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On the other hand, it looks like AFe may perform better. Here's a test:
http://shopping.na3.netsuite.com/c.1066071/site/pdf/ISO_5011_Test_Report_for_AFE_ProDry_75-80882.pdf

Summary - it seems that the AFe prodry filter has a lower restriction per flow rate (and maybe linear relationship) whereas the factory paper GM filter has a higher and exponential relationship per flow rate. Second the Prodry measures 50% more efficient at trapping dust across the CFM range than the GM paper filter.

Note this is for their prodry filter. The oiled 5R filter, which comes with their N54 kit, I've not found any tests yet. But my understanding is oiled filters (ala K&N and possibly AFe 5R oiled) are not as efficient for trapping dust.

And someone really wants to go nuts, here's more.

Filippo
 
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Rob09msport

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My mistake I am referring to their dry media I just dont know their product line. They have line 4 diff levels of filtration vs flow you can choose from varying from track max hp to street, off road, and extreme offroad aka sand rail type stuff.
But ya I wouldnt swap out one oiled for another oiled
 

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Posting this just as a data point... The following was done many years ago on Spec racecar with a small NA motor, 200ish HP. Every HP counted for an advantage, though.

I did a fair amount of testing filters where I tested the OEM paper, K&N and a few others (can't remember all the brands) back to back on a dyno. No noticeable difference between any of them with power. So I ran the OEM paper one. Fast forward a couple of race events and back to the dyno and it was down on power. WTF??? I put new plugs, coils, checked cam timing and I don't even remember what anymore. I was pulling my hair out (whats left of it) and it turned out the paper filter had collapsed on itself. It was brand spankin new clean, but the accordion folds has sucked together and permanently deformed. Tossed another filter in there and instantly 7 more HP. Haven't run a paper filter in a racecar ever since. Now that I know to look for it I have seen other track friends have the same problem.

The paper filter just can't take the constant beating of 4k-7k rpms of airflow non stop over an extended amount of time such as a 50 minute sprint race or multiple hour long enduro.
 

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derekgates

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This thread certainly pushed me over the edge to switch away from DCIs and go back to a stock intake setup. I picked up a Z4 N54 intake lid and an AFe ProDry filter. BuraQ did some investigation on the lid differences between 3 series and Z4: https://www.e90post.com/forums/showpost.php?p=22113077&postcount=64 (at least I think this is BuraQ since his original name got banned?)

The DCIs were making far too much noise and sucking in hot air was not ideal. More velocity of air with DCIs, sure, but the turbos have to work harder to hit boost targets. The noise was completely obnoxious with inlets. I tried BMS DCIs, AFe DCIs (on top of intake manifold). On top of all of that... how good is the filtration of these DCIs? The AFe seems better due to being dry but the noise is not worth it.

Test drove car last night and turbos are 'silent', pedal feel is fantastic. Happy to have high flow AND good filtration (compared to K&N).
IMG_1452.jpeg
 

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LessIsMore

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So what is the best alternative to DCI for those making 500 - 600 horsepower ? I doubt any version of the factory air box set up would be able to keep up ... or could it?
 

derekgates

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So what is the best alternative to DCI for those making 500 - 600 horsepower ? I doubt any version of the factory air box set up would be able to keep up ... or could it?

In the thread I linked, BuraQ is running a ~500HP with a closed intake (stock? AFe Momentum?): https://www.e90post.com/forums/showpost.php?p=22118809&postcount=87

BuraQ was also showing a 1M with the AFe Momentum GT closed intake getting close to 500HP: https://www.e90post.com/forums/showpost.php?p=22113760&postcount=71

I certainly think a "Mr.5 Intake" would be able to handle more power, if you can run one (non AT?). It has all of the flow of stock intake box as well as another filtered intake from low, dense air in bumper area. I love the setup of: https://www.e90post.com/forums/showthread.php?p=8762970

I bought ALL of the parts for the setup including another stock box, the K&N velocity intake, flanges, couplings, etc etc.... and found out I could not route cold air from lower bumper due to having a DCT 335is (need to sell as a kit to someone). Instead, I am going with the Z4 lid and figure out flow when I am upgrading turbos...
 

aus335iguy

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I have the Afe intake (Not the momentum but the first ones with a closed lid) and cant say ive had any issues with it other than the fact it is a little noisier than stock. It has the dry element in it.
 

derekgates

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I have the Afe intake (Not the momentum but the first ones with a closed lid) and cant say ive had any issues with it other than the fact it is a little noisier than stock. It has the dry element in it.

That's what I took out of my car. I never had 'issues' other than far too much noise and the fact it was sucking in hot air. Looked great though! :)

Here is a pic when I first installed the AFe. <3
IMG_5440.JPG
 

fmorelli

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That's what I took out of my car. I never had 'issues' other than far too much noise and the fact it was sucking in hot air.
The AFe dry filter is better than OEM paper I believe, in flow and dust catching. Certainly that filter has more surface area. I don't get, though, why it was sucking in hot air? And how do you determine that, if I may ask?

Filippo