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Old 12-19-2015, 01:22 PM   #1
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Default Amsoil Air filter pressure drop tested-Need better air filter

I measured the pressure drop on the Amsoil EAAU3090 Filter on my Supercharged setup. It's a large air filter. Here's an old pic to show how big this filter actually is. It's now mounted in the bumper for colder air.




See the secondary map trace. It drops to 80kPa at 7,000 RPMs!




I emailed Amsoil about why this one sucks, will update if I hear anything back from them.


What air filter should I run? K&N? Something else? Looks like I could be flowing about 20% more air if I had a perfect air filter with no pressure drop. That's 20% more power!
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Amsoil Air filter pressure drop tested-Need better air filter-20150406_214629_zpshngrwra7.jpg   Amsoil Air filter pressure drop tested-Need better air filter-air%2520filter_zpsy2ndacro.png  
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Old 12-19-2015, 01:54 PM   #2
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Velocity stack
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Old 12-19-2015, 02:14 PM   #3
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Quote:
Originally Posted by aidandj View Post
Velocity stack
Those don't filter very well.
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Old 12-19-2015, 03:26 PM   #4
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Before you get all prissy with amsoil I'd pop the hood and run a short length intake, make sure all your bends aren't causing the pressure drop. You probably have more corners than in the pictures, even, if you've moved the filter again. Might be that no filter you'd pick will help...
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Old 12-19-2015, 03:38 PM   #5
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+1, or even just do a pull without the filter.
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Old 12-19-2015, 04:09 PM   #6
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Quote:
Originally Posted by deezums View Post
Before you get all prissy with amsoil I'd pop the hood and run a short length intake, make sure all your bends aren't causing the pressure drop. You probably have more corners than in the pictures, even, if you've moved the filter again. Might be that no filter you'd pick will help...
I have a better CAI now without all those bends.

Also, I measured the pressure drop 3" away from the air filter to eliminate bends from the CAI as the source of the pressure drop. I measured the pressure drop before and after the bends, and the pressure drop is the same (within 1kPa). All the pressure drop is coming from the air filter.
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Old 12-19-2015, 04:10 PM   #7
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A long of places list the CFM of their filters. Have you done the math to see how much air your supercharger is moving at max load and found a filter that fits that?
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Old 12-19-2015, 04:14 PM   #8
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You are not going to find a filter with zero restriction AND filtration. Fluid dynamics dont work that way.
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Old 12-19-2015, 04:17 PM   #9
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Quote:
Originally Posted by aidandj View Post
A long of places list the CFM of their filters. Have you done the math to see how much air your supercharger is moving at max load and found a filter that fits that?
Assuming 90% volumetric efficiency on the SC and no air filter restriction, around 920 CFM at 7,000 RPMs. Any filter that's rated for some CFM has an associated pressure drop at that rating. I would need to know the test standard to compare results. As an example, my filter I have now is probably flowing 700+CFM, but with a terrible pressure drop.

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You are not going to find a filter with zero restriction AND filtration. Physics dont work that way.
Sure, that's obvious. Is there anything better than what I have though? Or is there something that flows better at the expense of filtration?
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Old 12-19-2015, 04:19 PM   #10
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Your op mentioned a "perfect filter" with "no pressure drop" I was just pointing out that there is no such thing.

I've made north of 400hp on a Autozone bought Spectra Air filter.
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Old 12-19-2015, 04:21 PM   #11
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Did you measure the pressure drop with that filter? I'm making power too, but my filter is holding me back quite a bit.
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Old 12-19-2015, 04:21 PM   #12
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Old 12-19-2015, 04:28 PM   #13
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Thanks for the link. That one is listed as having a 4" inside diameter for the intake pipe to connect. Are you running a 4" diameter intake? Mine is a 3" as is my current air filter.
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Old 12-19-2015, 04:40 PM   #14
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It comes with several adapters. But all my piping is 3" (I use a 75mm 4.6L Mustang throttle body and TPS)
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Old 12-19-2015, 04:54 PM   #15
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Where did you place the pressure sensor?
Did you try removing the filter to get a quick baseline of a no-filter readout? Your pressure loss may be in the pipe inlet (which is why my AVO inlet has a bell mouth under the filter)
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Old 12-19-2015, 05:38 PM   #16
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The sensor is a few inches behind the air filter, as close as I can possibly get it. I did not try removing the filter as that could result in me possibly sucking something terrible into the SC, though it would be nice to know what affect that would have. I think this filter has a bell mouth made into the bottom of the filter.

My bypass valve actuator died on me, so I gotta get that fixed first. But then I'm going to try out a couple different filters and see if any flow better than the one I have. Plan is to test the one, or one similar to, the Spectre Eric is running, and also a K&N of similar size.
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Old 12-19-2015, 07:48 PM   #17
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Hybrid Racing 3" Velocity Stack and Filter Hybrid Racing

I never did any testing, but I have a 2.5" version of that on my 130hp stock motor. K&N makes a bunch of 6" filters that can be swapped onto the velocity stack.
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Old 12-22-2015, 04:00 PM   #18
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Here's what Amsoil had to say about the 20% loss in airflow.

Quote:
As you know, a filtesr primary function is to remove dirt particles form the incoming air. Having no filter means the lowest pressure drop will occur, but no dirt will be removed. On the other hand, the most efficient media for the removal of dirt will result in the greatest pressure drop through the filter. We have standards on the particle size removal level that we feel is acceptable. But this standard means the media may lead to s bit higher pressure drop than a coarser media will, which is what you are seeing. Which filter you choose will depend on both the engine wear protection/engine life desired and your quest for speed at any price. .
So I'm guessing my results are normal with their filter at this CFM. New bypass diagphram will be here Thurdsday, so once it's back on the road I'll test some other filters and see how they compare. Funny thing is I'm at 92% duty cycle now at 12:1 AFR's, so going to need more fuel if I do find a much better air filter!
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Old 12-22-2015, 04:34 PM   #19
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I'm going to be really surprised if you find anything else that flows more short of a screen mesh or no filter at all. That thing Is massive, I've seen smaller filters on 600-700whp cars.

But do it, for science
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Old 12-22-2015, 05:05 PM   #20
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Quote:
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I'm going to be really surprised if you find anything else that flows more short of a screen mesh or no filter at all. That thing Is massive, I've seen smaller filters on 600-700whp cars.

But do it, for science
The funny thing is, when I put that filter on I had several people on m.net tell me that was way too big/overkill. And now I know it's a restriction!

I think the amsoil filter is just really restrictive due to the material it's made from and the huge amount of air I'm pulling through it combined. There's no way everyone just drives around loosing 20% of their potential power because of an air filter.

Absolutely will be testing at least a K&N of similar size, and probably the one Eric linked if I can find it locally.
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