asasa11

Air Filter with best Filtration

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2,108
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Arizona
Dust masks are a great analogy, because they have significantly more surface area than a person's windpipe, just like an 'average' air filter has significantly more surface area than an 'average' throttle body. And yes, you can both feel and measure empirically the difference in dust masks of various filtration levels.
 
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42,574
Location
Ontario, Canada
Originally Posted by CR94
Originally Posted by OVERKILL
... The factory filter flows 1,080CFM. ...
At what assumed pressure drop?
I think that's 15" of water IIRC. I'd have to look it back up. Most filter manufacturers don't share their flow data unfortunately. The TB flow figures are all at the standard 28" of water.
 
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42,574
Location
Ontario, Canada
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
As I said earlier, you can easily verify if the filter is a problem using a vacuum gauge plumbed into the box or plumbing on the clean side of the filter. The K&N filter restriction gauge is probably an ideal fit, as it is both very sensitive (much more so than the typical diesel ones) and locks in place at the restriction level, so you can go out, do a WOT run and see if it showed any restriction. . . . So, my 392 makes 475HP, so VE is 88%, which pegs my CFM requirements right around 650, meaning the factory filter is VERY generously sized.
Regardless of how much CFM the throttle body is rated to flow, if the filter (and intake tubing) adds some flow restriction (they all do to some degree), then there is a corresponding delta-p across the filter and ducting which reduces the absolute air supply pressure at the entrance of the throttle body by that amount - talking about NA engines here. If you compared a free flowing filter to a flow restrictive filter, you'd see an increased delta-p on the filter restriction gage across the filter at WOT with a more restrictive filter, and should also see a corresponding HP loss on the dyno. Throw a nearly clogged filter in the box and see how much filter delta-p there is and how much HP is lost at WOT. Any time there is less absolute air supply pressure at the entrance of the throttle body, there is less air flow volume going into the engine, regardless of how big the throttle body is.
Right, but again, this is all easy verified with a restriction gauge, which is why I recommended trying it. It's the easiest way to tell if the filter is in fact a restriction and also doubles as a filter change interval device once in place. I've run a sensitive vacuum gauge on the back side of an airbox before to test with very generously sized plumbing when trying to ensure there were no restrictions on a pretty deep breathing N/A 302, blindly tossing a K&N on something because of a notion that its "mad flowz" is going to be of benefit without actually testing beforehand and giving up the superior filtration of the stock filter isn't doing one any favours is my main point here. There's an actual method, which both of us appear to agree on, in determining if an upgrade to the air intake tract is required. One cannot blindly and universally state they there is or is not an issue without following that method.
 
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42,574
Location
Ontario, Canada
Originally Posted by wemay
Thanks OVERKILL, Good post. As is the case with so many automotive topics, not every factory filter is restrictive, I'm sure. Especially not those affixed to 392's. But drop one into a VW EA888 Buddack and you'll definitely notice the difference at the dyno (numbers) and in seat of the pants throttle response...not to mention sound.
An aftermarket CAI is always louder. Heck, you'd make the fox louder just by removing the factory silencer, same with the Expedition, where I removed the silencers from the intake tract, which also had a significant impact on sound, regardless of the filter in the housing. As I said, it's easy enough to verify with a restriction gauge, which are pretty cheap and also will let you know when your filter needs to be changed or cleaned, depending on what you've chosen. The ones K&N sells come from Donaldson, so they are a good piece.
 
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24,064
Location
PNW
Originally Posted by OVERKILL
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
As I said earlier, you can easily verify if the filter is a problem using a vacuum gauge plumbed into the box or plumbing on the clean side of the filter. The K&N filter restriction gauge is probably an ideal fit, as it is both very sensitive (much more so than the typical diesel ones) and locks in place at the restriction level, so you can go out, do a WOT run and see if it showed any restriction. So, my 392 makes 475HP, so VE is 88%, which pegs my CFM requirements right around 650, meaning the factory filter is VERY generously sized.
Regardless of how much CFM the throttle body is rated to flow, if the filter (and intake tubing) adds some flow restriction (they all do to some degree), then there is a corresponding delta-p across the filter and ducting which reduces the absolute air supply pressure at the entrance of the throttle body by that amount - talking about NA engines here. If you compared a free flowing filter to a flow restrictive filter, you'd see an increased delta-p on the filter restriction gage across the filter at WOT with a more restrictive filter, and should also see a corresponding HP loss on the dyno. Throw a nearly clogged filter in the box and see how much filter delta-p there is and how much HP is lost at WOT. Any time there is less absolute air supply pressure at the entrance of the throttle body, there is less air flow volume going into the engine, regardless of how big the throttle body is.
Right, but again, this is all easy verified with a restriction gauge, which is why I recommended trying it. It's the easiest way to tell if the filter is in fact a restriction and also doubles as a filter change interval device once in place. I've run a sensitive vacuum gauge on the back side of an airbox before to test with very generously sized plumbing when trying to ensure there were no restrictions on a pretty deep breathing N/A 302, blindly tossing a K&N on something because of a notion that its "mad flowz" is going to be of benefit without actually testing beforehand and giving up the superior filtration of the stock filter isn't doing one any favours is my main point here. There's an actual method, which both of us appear to agree on, in determining if an upgrade to the air intake tract is required. One cannot blindly and universally state they there is or is not an issue without following that method.
If you want to do a complete analysis/test, put an absolute pressure sensor for ATM, one for absolute pressure after the air filter and one for absolute pressure at the entrance of the throttle body. That way, you can see the complete pressure drop in the system from the ATM to the throttle body. As mentioned, it's the absolute pressure at the throttle body entrance that determines how much air flow is going into the throttle body. Every intake system and air filter combo has a pressure drop (delta-p) from air flowing through it - and the higher the air flow volume the larger the pressure drop. You'll always get more HP from a less restrictive system because it will allow more air flow volume to the throttle body due to less delta-p pressure drop ... again, only talking only about NA engines.
 
Messages
42,574
Location
Ontario, Canada
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
As I said earlier, you can easily verify if the filter is a problem using a vacuum gauge plumbed into the box or plumbing on the clean side of the filter. The K&N filter restriction gauge is probably an ideal fit, as it is both very sensitive (much more so than the typical diesel ones) and locks in place at the restriction level, so you can go out, do a WOT run and see if it showed any restriction. So, my 392 makes 475HP, so VE is 88%, which pegs my CFM requirements right around 650, meaning the factory filter is VERY generously sized.
Regardless of how much CFM the throttle body is rated to flow, if the filter (and intake tubing) adds some flow restriction (they all do to some degree), then there is a corresponding delta-p across the filter and ducting which reduces the absolute air supply pressure at the entrance of the throttle body by that amount - talking about NA engines here. If you compared a free flowing filter to a flow restrictive filter, you'd see an increased delta-p on the filter restriction gage across the filter at WOT with a more restrictive filter, and should also see a corresponding HP loss on the dyno. Throw a nearly clogged filter in the box and see how much filter delta-p there is and how much HP is lost at WOT. Any time there is less absolute air supply pressure at the entrance of the throttle body, there is less air flow volume going into the engine, regardless of how big the throttle body is.
Right, but again, this is all easy verified with a restriction gauge, which is why I recommended trying it. It's the easiest way to tell if the filter is in fact a restriction and also doubles as a filter change interval device once in place. I've run a sensitive vacuum gauge on the back side of an airbox before to test with very generously sized plumbing when trying to ensure there were no restrictions on a pretty deep breathing N/A 302, blindly tossing a K&N on something because of a notion that its "mad flowz" is going to be of benefit without actually testing beforehand and giving up the superior filtration of the stock filter isn't doing one any favours is my main point here. There's an actual method, which both of us appear to agree on, in determining if an upgrade to the air intake tract is required. One cannot blindly and universally state they there is or is not an issue without following that method.
If you want to do a complete analysis/test, put an absolute pressure sensor for ATM, one for absolute pressure after the air filter and one for absolute pressure at the entrance of the throttle body. That way, you can see the complete pressure drop in the system from the ATM to the throttle body. As mentioned, it's the absolute pressure at the throttle body entrance that determines how much air flow is going into the throttle body. Every intake system and air filter combo has a pressure drop (delta-p) from air flowing through it - and the higher the air flow volume the larger the pressure drop. You'll always get more HP from a less restrictive system because it will allow more air flow volume to the throttle body due to less delta-p pressure drop ... again, only talking only about NA engines.
I don't disagree, but I don't think that's a reasonable proposal for Joe DIY wanting to find out if his air filter is restrictive. A simple sensitive restriction gauge like the Donaldson unit K&N sells should be sufficient for the task of determining if the filter is an issue. The plumbing, while germane to this discussion, is a separate issue. In many cases, silencers fitted into the intake tract can be easily removed to make it more free-flowing. In my testing, since I was using large diameter aluminum piping with minimal bends, there was no need to analyze beyond the filter housing.
 
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PNW
Originally Posted by OVERKILL
I don't disagree, but I don't think that's a reasonable proposal for Joe DIY wanting to find out if his air filter is restrictive. A simple sensitive restriction gauge like the Donaldson unit K&N sells should be sufficient for the task of determining if the filter is an issue.
Yep, that's not a practical DIY test ... just describing to show that there is a pressure loss all the way from the ATM to the throttle body, and it's the absolute pressure at the entrance of the throttle body that's going to determine how much air volume the engine will ingest. And I agree that if the intake tubing is big and free flowing, then it's mostly the filter that's going to differ in respect to the delta-p pressure drop as a function of air flow volume being sucked in by the NA engine.
 
Messages
42,574
Location
Ontario, Canada
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
I don't disagree, but I don't think that's a reasonable proposal for Joe DIY wanting to find out if his air filter is restrictive. A simple sensitive restriction gauge like the Donaldson unit K&N sells should be sufficient for the task of determining if the filter is an issue.
Yep, that's not a practical DIY test ... just describing to show that there is a pressure loss all the way from the ATM to the throttle body, and it's the absolute pressure at the entrance of the throttle body that's going to determine how much air volume the engine will ingest. And I agree that if the intake tubing is big and free flowing, then it's mostly the filter that's going to differ in respect to the delta-p pressure drop as a function of air flow volume being sucked in by the NA engine.
cheers
 
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2,229
Location
SE MI
Jumping into this late, but the stock airbox/ducts/paper filter on Ford EcoBoost is not a restriction at all. There's been extensive testing that showed negligible gains with using a K&N filter on EcoBoost, same goes for hot air boxes and such. I did my own tests and found the same. There is a pressure drop from using the paper filter vs. K&N but it is in the tenths of a psi, hardly enough of a restriction when we are talking magnitudes of 20+ psi.
 
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24,064
Location
PNW
Originally Posted by metroplex
Jumping into this late, but the stock airbox/ducts/paper filter on Ford EcoBoost is not a restriction at all. There's been extensive testing that showed negligible gains with using a K&N filter on EcoBoost, same goes for hot air boxes and such. I did my own tests and found the same. There is a pressure drop from using the paper filter vs. K&N but it is in the tenths of a psi, hardly enough of a restriction when we are talking magnitudes of 20+ psi.
If boost pressure is controlled by a manifold absolute pressure sensor, then the flow resistance of the filter won't make any real difference. The turbo will just work a hair harder to reach the same manifold boost pressure. Intake ducting, airbox and filter flow resistance impacts normally aspirated engines way more than boosted engines.
 
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66
Location
Australia
Originally Posted by ZeeOSix
Originally Posted by metroplex
Jumping into this late, but the stock airbox/ducts/paper filter on Ford EcoBoost is not a restriction at all. There's been extensive testing that showed negligible gains with using a K&N filter on EcoBoost, same goes for hot air boxes and such. I did my own tests and found the same. There is a pressure drop from using the paper filter vs. K&N but it is in the tenths of a psi, hardly enough of a restriction when we are talking magnitudes of 20+ psi.
If boost pressure is controlled by a manifold absolute pressure sensor, then the flow resistance of the filter won't make any real difference. The turbo will just work a hair harder to reach the same manifold boost pressure.
Which increases lag
 
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24,064
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PNW
Originally Posted by adams355
Originally Posted by ZeeOSix
Originally Posted by metroplex
Jumping into this late, but the stock airbox/ducts/paper filter on Ford EcoBoost is not a restriction at all. There's been extensive testing that showed negligible gains with using a K&N filter on EcoBoost, same goes for hot air boxes and such. I did my own tests and found the same. There is a pressure drop from using the paper filter vs. K&N but it is in the tenths of a psi, hardly enough of a restriction when we are talking magnitudes of 20+ psi.
If boost pressure is controlled by a manifold absolute pressure sensor, then the flow resistance of the filter won't make any real difference. The turbo will just work a hair harder to reach the same manifold boost pressure.
Which increases lag
Maybe slightly depending on the turbo, But really doesn't change HP like on a NA engine. A very restrictive intake and filter can cause some closed throttle to WOT "lag" too on a N A engine. It takes a bit of time for air mass to move (mass inerita) when there's a gigantic change in throttle opening.
 
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65
Location
Ca
Originally Posted by ZeeOSix
Originally Posted by adams355
Originally Posted by ZeeOSix
Originally Posted by metroplex
Jumping into this late, but the stock airbox/ducts/paper filter on Ford EcoBoost is not a restriction at all. There's been extensive testing that showed negligible gains with using a K&N filter on EcoBoost, same goes for hot air boxes and such. I did my own tests and found the same. There is a pressure drop from using the paper filter vs. K&N but it is in the tenths of a psi, hardly enough of a restriction when we are talking magnitudes of 20+ psi.
If boost pressure is controlled by a manifold absolute pressure sensor, then the flow resistance of the filter won't make any real difference. The turbo will just work a hair harder to reach the same manifold boost pressure.
Which increases lag
Maybe slightly depending on the turbo, But really doesn't change HP like on a NA engine. A very restrictive intake and filter can cause some closed throttle to WOT "lag" too on a N A engine. It takes a bit of time for air mass to move (mass inerita) when there's a gigantic change in throttle opening.
Turbo engines are usually affected more than NA engines from intake side restriction though it obviously depends on the severity of the restriction. Not so much on the pressure side. Boost pressure in the manifold doesn't change because the wastegate allows the turbo to work harder since it's now dealing with a higher pressure ratio at a given boost level. It's not much different than what happens when you turn up the boost: a little more exhaust back pressure, a hotter charge temperature... except boost stayed the same. A little less power at the same manifold pressure. Pikes peak cars illustrate this. The turbo cars tend to retain more of their "sea level hp" at elevation because the manifold sees the same pressure regardless ,but the charge air quality is diminished somewhat and backpressure is higher so they still lose some power. Regarding restrictions overall, you want the intake tract to be invisible to the turbo or TB. Of course this means within reason because to move air through a tube even if it's 12" diameter and the filter has 10 sq ft of media, there will still be a drop across the media though it would take specialized tools to measure. Any positive inertial gains pre-throttle body (NA) will be at and near full throttle in the second or so after the throttle snapped open and the intake tract is in a steady state somewhat cohesive flow. Upon tip-in or the first second or so you go from idle/low throttle to full throttle you want the throttle valve to think it's in a wide open field with no tube around it. The air will be rarified close by, it has to be, but if everything comes together perfectly you may get the tiniest gain from a well engineered pre-TB filter/tube kit. i can't imagine the level of restriction required to cause a loss in throttle response on a fuel injected car though. As you approach full throttle it will restrict you more and more. The TB being mounted too far from the intake plenum, and/or too much volume between the TB and intake valves will be a nightmare. Now that I'm rambling about nothing and boring even myself I should mention it's usually a somewhat safe guess that not a lot is being left on the table regarding inlet restrictions. The money spent developing an engine and chasing just a couple extra hp is huge. They usually aren't going to restrict the inlet down with a cheap piece of paper instead of spending a couple pennies for a larger filter. And that filter not only has to be of no significant restriction when new and clean it has to have enough capacity to still be free of restriction when it's not perfectly clean. Manufacturers have a stricter rule set, they have to meet noise standards. They can't rely on the customer to oil a high flow filter. They have to protect the filter from direct contact with debris and the filter and engine fr water intrusion. Being free from those things, we can usually get more power from a given setup but a lot of times it's after a round of mods where flow requirements are higher. I just got a car and looked at the intake tract and saw signs of poor filtration. Luckily it was light dust and not granules of sand or whatever the car has been through but the compressor wheel has slightly suffered though not bad and tracing it out to the end was a K&N under the car with a direct line of sight to it from everything the car sees in its lifetime. I'm no K&N fan as it is and when I have to use one I usually shelter it and at least avoid line of sight placement a foot off the ground. That's my sob story for today.
 
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Location
Ohio
Originally Posted by Al
Fram Ultra. 20 microns at 99%. https://www.youtube.com/watch?v=oK_hMFIBva8 Seems like a no brainer.
But needs to be changed every 12k? My wifes cars oem Recommendation is 30k. I inspect it at every oci which is 5k and it still looks very good and I just did it's fifth service. I'm definitely gonna change it next time but it will be oem which isnt much more than a Fram.
 
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2,495
Location
IL
Well, if filtration was THAT important, we would have HEPA air filters for cars. HEPA filters have been around a while, and they do last a while. So why are they not being up sold to the auto crowd for 20 more bucks?
 
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Location
No Tyson in Tonganoxie KS!
Originally Posted by Vern_in_IL
Well, if filtration was THAT important, we would have HEPA air filters for cars. HEPA filters have been around a while, and they do last a while. So why are they not being up sold to the auto crowd for 20 more bucks?
You just answered the question. Its 20 more dollars. Cost is usually priority numero uno.
 
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1,140
Location
USA
The engine wants a certain volume of air and all air filters restrict. The way I see it is as long as the clear filter pore openings exceed the throttle bore opening that's all that matters. Since all filters restrict the only way an engine gets all the air it needs is without an air filter if restriction is not allowed.
 
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At WOT the filter will show the most flow restriction because it's the operating condition with the largest delta-p across the filter due to the largest air volume demand. If Filter A has more delta-p than Filter B at WOT, then the engine will be ingesting a little less air, and will make a little less HP with Filter A than it would with Filter B. It's that simple.
 
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