The Great air filter debate - my findings & observations

[GlennSullivan]

I’m convinced that if manufacturers could increase gas engine mileage (and protect the engine) by 2 mpg by simply installing a different air filter - it would have already been done.

Massive amount of research is done by OEM gas vehicle manufacturer’s to increase fuel mileage, even slightly.

A simple engine air filter change probably has been tested repeatedly to determine its affects on fuel mileage. The manufacturer also have to provide as much engine protection with the current filter system as possible, and muffle engine noise. That is why they use the current intake set-ups and filters for mainstream vehicles.

As you say and I agree, engine protection and intake noise are the keys to why OEMs don't go this route.

 

[Fastcar]

Actually with a supercharger or turbocharger, the intake air is warmer than ambient. When air is compressed it heats up, even after going through an intercooler (a unit that sits between the super/turbo and cools the compressed air), the air in a supercharged / turbocharged engine is almost always warmer than the ambient air outside.

As I said above, using a K&N filter will generally (not always) allow the engine to draw more air into the engine. As that additional air passes the MAS Air meter, it signals the ECU to have the injectors send more fuel to the cylinders. More fuel burned (assuming the same A/F ratio) more power make.

At the end of the day, changing to a K&N will not produce earth shattering power increases. typically somewhere between 2 & 5 HP

If the intake duct / tube on a vehicle is inefficient and you were to change both the filter and the intake duct at the same time, you could achieve more of a gain. According to K&N's dyno testing, a 2017 Expedition 3.5 T/T would gain about 7HP by changing the intake duct / filter system.

I'm not particularly looking for a few HP in either of our Expeditions, but if changing the filter element will get an extra 2mpg, that would make sense to me.

I took notice of "According to K&N's dyno testing". That is the crux of the issue. Their Dyno! Their pre-set conditions with regard to tempeture of the engine, abient temp. posotion of the filter and so on.. I'm not aware of any independet before and after dyno test that K$N paticipated in. There are so many ways to control the test.

 

[GlennSullivan]

I took notice of "According to K&N's dyno testing". That is the crux of the issue. Their Dyno! Their pre-set conditions with regard to tempeture of the engine, abient temp. posotion of the filter and so on.. I'm not aware of any independet before and after dyno test that K$N paticipated in. There are so many ways to control the test.

There are a lot of ways to "control" a dyno test without actually falsifying it. Leave off SAE correction for all testing, test the OEM filter at 3:00 in the afternoon when ambient air is 90 degrees and the K&N at 7:00 the next morning when ambient is 70 degrees, there is probably 1% just in air temp. However, I don't think that is what is happening.

I think C5Coupe has the answer. It comes down to the density of the filter media the OEMs require for engine protection and the noise level they are willing to accept.

 

[texasscot]

There is a huge industry based on automotive “hacks” that purport to improve on ludicrous, inefficient OEM designs. You’d think that car manufacturers would employ proper engineers lol. Go faster stripes anyone?

 

[99WhiteC5Coupe]

There is a huge industry based on automotive “hacks” that purport to improve on ludicrous, inefficient OEM designs. You’d think that car manufacturers would employ proper engineers lol. Go faster stripes anyone?

I think the red brake calipers also add 10 hp?

 

[99WhiteC5Coupe]

Anyone old enough to remember turning the circulator engine air filter housing lid upside down on V-8 engines with a 4-barrel carburetor, to allow more intake air and enable a loud engine roar when the two rear carburetor barrels opened on wide-open throttle?

 

[Fastcar]

There are a lot of ways to "control" a dyno test without actually falsifying it. Leave off SAE correction for all testing, test the OEM filter at 3:00 in the afternoon when ambient air is 90 degrees and the K&N at 7:00 the next morning when ambient is 70 degrees, there is probably 1% just in air temp. However, I don't think that is what is happening.

I think C5Coupe has the answer. It comes down to the density of the filter media the OEMs require for engine protection and the noise level they are willing to accept.

I think he's corect myself. I remember a ZO6 I owned and it didn't have a K$N on it. At that time GM was and had spent all kinds of money on research, development, syn oils and wind tunnels to wring out every bit of HP out of it. If it was of benifit they undoubtedly would have used it.

 

[Fastcar]

Anyone old enough to remember turning the circulator engine air filter housing lid upside down on V-8 engines with a 4-barrel carburetor, to allow more intake air and enable a loud engine roar when the two rear carburetor barrels opened on wide-open throttle?

I have to admit I remember. Which brings me to my probably last on K$N. The running joke was the roar you heard form the addition of K&N was them sucking money out of your pocket, not HP. Human nature is when you spend a bunch of money on some phoney baloney thing on your engine you don't tell your buddies it was a pos and you got screwed.

 

[bb37]

There is a huge industry based on automotive “hacks” that purport to improve on ludicrous, inefficient OEM designs.

Hence, all those ads in the back of Popular Mechanics magazine for 100 MPG carburetors that the Detroit car companies don't want you to know about. Extra points if you dress a male model in a white lab coat to show the carburetor in the ad.

 

[BigOleFordFan]

It comes down to the density of the filter media the OEMs require for engine protection and the noise level they are willing to accept.

It ALSO comes down to the almighty buck, or the penny in this case, as to how thin, or fat, they want their profit margins to be vs. what they are "willing to accept"....

And unless I'm mistaken, maximum noise levels are at least somewhat regulated/dictated by the DOT/EPA, at least on OEM setups/parts that roll off the assembly lines...which unfortunately does not usually apply to aftermarket parts...

 

[EC07EB]

 

[GlennSullivan]

Anyone old enough to remember turning the circulator engine air filter housing lid upside down on V-8 engines with a 4-barrel carburetor, to allow more intake air and enable a loud engine roar when the two rear carburetor barrels opened on wide-open throttle?

Unfortunately, I am old enough to remember all the tricks from those days. In my defense I had older sisters whose boyfriends got me started down the "burning gasoline hobby" path very early in life LOL.

 

[JamaicaJoe]

Well, after reading many threads/discussions on the pros, cons, and opinions on the differences (if any) between different types/brands/tiers of air filters and whether or not they could/do have any effect on performance/mpg/horsepower etc, I decided to do my own little test and see what happened.

So my vehicle is in my sig, and with the following info, I proceeded:

A) 4x tanks of Premium 93 Exxon gas before & during the test, which is what I normally run anyways

B) Tires rotated & balanced, and oil/filter changed (Full Synth 5W-20 Mobile One) 2 weeks prior to test

C) 2 rounds of 3 mostly identical 200 mile trips, ~98% interstate and ~2% in-small city driving...

D) Maintained an average speed of 65mph by using cruise control as much as possible

Before the test, I was running a Fram premium air filter, and was getting ~11-13 mpg on average

For the test, I installed a K&N Premium 75K mile Oiled Filter, and am now getting ~17-18 mpg on average....

SO..... my observations are that I noted a fairly significant increase in responsiveness and acceleration during the test, especially when I had to step on it a few times to enter the freeway or to go around & pass some slow-poke doing 45mph in a 70 zone, and very quickly found myself going 80mph + in a 70 and had to let off the gas for a few minutes....

Even in the slower city rides, I could feel the beast wanting to take off like a young bull at mating time, and had to be real careful about how much pedal to give it

So there it is...... like it, don't like it, agree with it or disagree with it, but I'm hooked on my new K&N filter, at least for the time being, and will update this post in a month or 2 if there are any significant changes, good, bad or otherwise...

I would love to see that increase in MPG. My original truck was a 1993 E350 15 passenger van and the 13 MPG was making me sad. I bought a smaller, lighter 2001 EXPY and then still got 13 MPG. Then the adulturated gasohol scam cost me a mile or two. My flex fuel 2013 does not do any better. I think the results of your test call for some repeated tests, cleaned MAF sensors, fuel trim numbers compared. While we are at it what is best way to clean MAF sensor in a 3rd gen? Maybe I should be doing that?

 

[GlennSullivan]

I would love to see that increase in MPG. My original truck was a 1993 E350 15 passenger van and the 13 MPG was making me sad. I bought a smaller, lighter 2001 EXPY and then still got 13 MPG. Then the adulturated gasohol scam cost me a mile or two. My flex fuel 2013 does not do any better. I think the results of your test call for some repeated tests, cleaned MAF sensors, fuel trim numbers compared. While we are at it what is best way to clean MAF sensor in a 3rd gen? Maybe I should be doing that?

Joe
What gears are in your 2013 Expy? All of mine are 4x4 3.31 with open difs.

I have a 2011 and had a 2014, both 5.4/3 valve and both produced around 14.X combo and 17/18 hwy.

My 2017 3.5/TT gets 16.X combo and 20.X highway.

 

[BigOleFordFan]

I think the results of your test call for some repeated tests, cleaned MAF sensors, fuel trim numbers compared

Well, I just did another 80 mile trip yesterday, and still got ~15.5 mpg, but about 1/2 of that trip was in the city with a fair amount of stop & go traffic, so I'm sure that had some effect, but still not bad...

Even though I thoroughly cleaned my MAF before the test, I have ordered a new one, since AFAIK the current one is the original factory part, and am curious what effect, if any, a new one will have on the mpg...stay tuned

What do you mean by "fuel trim numbers" ??

 

[ManUpOrShutUp]

I'm getting 16.3mpg avg on my '11 EL with 219k miles. I have been running basic Motorcraft air filters since I got it.

 

[Fastcar]

Figured I'd toss this in. 2024 SPP 3:73 gears 4x4. My wife does most of the driving. Probably 50% highway, 50% city. She runs it in sport mode most of the time on the highway at 75 mph. She is in 2wd in the city. She usually fills at 1/2 tank. Today she was running me to the bone crusher and I asked how the mileage was. She says 18.4, is trying a couple of different brands. Told her it was a putor and would adjust and doubted she would see a difference.
Full disclsure, red calipers, and the bigger engine. Stock air filter.

 

[JamaicaJoe]

Joe
What gears are in your 2013 Expy? All of mine are 4x4 3.31 with open difs.

I have a 2011 and had a 2014, both 5.4/3 valve and both produced around 14.X combo and 17/18 hwy.

My 2017 3.5/TT gets 16.X combo and 20.X highway.

I will have to check the diff code on the VIN . I have a towing package, RWD.

 

[JamaicaJoe]

Well, I just did another 80 mile trip yesterday, and still got ~15.5 mpg, but about 1/2 of that trip was in the city with a fair amount of stop & go traffic, so I'm sure that had some effect, but still not bad...

Even though I thoroughly cleaned my MAF before the test, I have ordered a new one, since AFAIK the current one is the original factory part, and am curious what effect, if any, a new one will have on the mpg...stay tuned

What do you mean by "fuel trim numbers" ??

The fuel trim is a value that you have to scan for in the Mode 6 OBD2. It has short and long term values. I was watching "the Wizard" on Tik Tok and he had a customers car, Toyota I think, new engine running great, no codes, but the Check Engine light would not go off. Turns out he had a K&N cold air intake and the MAF was not happy and the engine was actually running very lean which makes one wonder about what happened to the original engine.

 

[DieselMonk]

Figured I'd toss this in. 2024 SPP 3:73 gears 4x4. My wife does most of the driving. Probably 50% highway, 50% city. She runs it in sport mode most of the time on the highway at 75 mph. She is in 2wd in the city. She usually fills at 1/2 tank. Today she was running me to the bone crusher and I asked how the mileage was. She says 18.4, is trying a couple of different brands. Told her it was a putor and would adjust and doubted she would see a difference.
Full disclsure, red calipers, and the bigger engine. Stock air filter.

If I drive it economical in eco mode on the highway, I get 22mpg. But short distance driving to town for work, errands etc. about 17.5mpg, regular gas, everything is bone stock on my Expy. Running the factory 22” tires it came with.
If I compare that to my old 2000 6L with a 4l80 back then, I got 17mpg as the best scenario on the highway and that went down to 11mpg in my short drive to town, work, errands etc. Putting a 21ft camper trailer on the back, it got 6mpg! Forgot to mention it had a 150l (39.something gallon) tank.