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OEM Air Filter - Oiled v. Dry?

5K views 12 replies 6 participants last post by  Jackson3010 
#1 ·
I'll soon be replacing the stock Motorcraft air filter on my '19 GT Premium 5.0L. Not ready yet to make a wholesale conversion to a cold air intake so I'll just be replacing the OEM Motorcraft with either a K&N or most likely an aFe filter. Question is to go oiled or dry - thoughts? What drop-in filters are you guys/gals using?
 
#2 ·
dry...………….




A Ford MasterTech made this videowhich talks directly about the aftermarket CAI’s.










Now please forgive, but a bit of the "Dutch Uncle" talking now..... you already have a CAI......
Ok, let's just take a look at basic physics.....
The2013 Mustang 5.0 V8, for example if close to stock (assuming 6,800 max rpm& 90% volumetric efficiency- note that is race car spec and likely higherthan reality) can only suck in a maximum of 535 CFM, and the OEM flat panel filter ( 12.375” x 9.675”) will flow 718cfm,


....so how can just a CAI force more air into an engine thatis already injesting everything it can? It can't plan & simple- basic lawsof physics without a forced induction system.


Testand Corporation conducted an ISO standards test onautomotive air filters which can be viewed at this link: Duramax Air FilterTesting * - Diesel Bombers.
“After only 24 minutes the K&N had accumulated 221gms ofdirt but passed 7.0gms. Compared to the AC, the K&N “plugged up” nearly 3times faster, passed 18 times more dirt and captured 37% less dirt.”
If you look at the flow data, WIX HP filters flow 98+% ofK&N and have a much smoother flow post filter plus excellent filtering, fora fraction of the price! on an OEM replacement unit.


I know...science and real data by an ISO certified testfacility.

The formula which is used by every air filter manufacturerin the world to determine the CFM for flat panel filters is...


Flat Panel CM= Length x Width x 6


So, take you relatively stock engine, calc the max CFM basedupon mfg specs; calc the max CFM the oem filter will flow....now show me howsticking a filter that will flow 900 CFM will increase the performance of anengine that can only suck in a max of 535 cfm? it can't


bad math, no science...all PR materials for the sticker hpcrowd! If you are looking for bling- ok, but otherwise save your $
 
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#6 ·
just echoing what the others have said -- for the stock airbox I'd stay with stock or equivalent dry filter and replace it on schedule (or sooner)

whether there is any gain to be had with aftermarket intake is a different debate . . .


....so how can just a CAI force more air into an engine thatis already injesting everything it can? It can't plan & simple- basic lawsof physics without a forced induction system.

...now show me howsticking a filter that will flow 900 CFM will increase the performance of anengine that can only suck in a max of 535 cfm? it can't . . . bad math,

yep, that is some bad math -- because it ignores the pressure drop through the system, which is the key factor in an intake because atmospheric pressure less the pressure drop through the intake is what pushes the air/fuel mix into the cylinders


that standardized flow test is based on some define pressure drop . . . if the aftermarket filter can flow the same amount of air with less pressure drop, theoretically it will result in more air/fuel mix in the cylinders and more power


an engine never "ingests all that it can" because that is dependent on the pressure through the system; that's why superchargers add power -- because they push more air/fuel mix into the cylinders; effectively increasing the amount of air/fuel mix that the engine can ingest -- a better flowing intake works on the same principle, only much less dramatic because the difference is much smaller


anyway for practical purposes the stock intake is very good and there probably is very little gain to be had with aftermarket intakes, but theoretically it is possible
 
#4 ·
Bryce,

I can think of one benefit to an oiled air filter. They say they last a million miles. Personally I've never owned a vehicle beyond 150,000 miles and never met anyone that has a oiler with a million miles on it.

IMHO there are more reasons to avoid oiled air filters. Cost of the filter and costly renew kits. The amount of time to clean and dry it before you can oil it and reinstall it. Over oiling the filter causes contamination to downstream sensors.

Its claimed oilers breath better and you get more power. Logically thinking its when the accelerator is planted to the floor. That's not my normal driving habit.

I had one car with a K&N wet filter and eventually reinstalled the factory air box and dry filter. Stay with a dry filter.

Even my 2012 with the R2300 uses a high flow air box with dry filter.

Erik
 
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#8 ·
yep, that is some bad math -- because it ignores the pressure drop through the system
[/QUOTE]

Not exactly, since there is no pressure drop in the oem intake system except at very low speed. What many view as an issue (is the plasticintake tube with its noise canceling design) actually increases airpressure. It is the same hydraulicconcept used by fire fighters creating water supply where psi is low. By havingthe air cross the path at a 90 degree angle, the pressure is increasedproportionally. Fire fighters use whatis called a “4-way valve” or “Blake Valve” at the hydrant where the water iscycled through the fire engine (pump) and sent back into the valve crossing thewater flow at a 90 degree angle. In thiscase it also acts as a sound canceling device! At low speeds, this can reduce the flow a tad (which is what most“feel”), but in terms of peak hp/tq, a good high flow filter is all that isneeded.


When I conducted a very crude, old school barometric pressure test to see where the highest pressure/air flow direction was at key speeds, I was very surprised to discover/ID the best air intake location for my Mark LT was just above the fan scroud...and the gains were only at 50mph+..... figuring Ford spent likely $1m designing the air intake systems I figured I might as well "leverage' their design...keeping the oem intake "box', I made an old school hemi-type ram air intake which connects to their box


.
and you are very right about the bad math out there....if a street engine can achieve 85-90% VE efficiency, they are lucky!
 
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#9 ·
....if a street engine can achieve 85-90% VE efficiency, they are lucky!
that's the technical term I was looking for: Volumetric Efficiency

Theoretically, a freer flowing air filter and intake can achieve higher volumetric efficiency, that is the point . . . the filter that "flows more air" at a given pressure drop (per that standard test), will flow the same amount of air with less pressure drop, leaving more pressure in the intake to push the air/fuel into the cylinders to achieve higher VE . . . lots of other dynamic affects going on also which makes it a lot more complicated than that, but that is the simplified view
 
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#12 ·
the short answer would have been way too short, then what would we talk about? LOL
 
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