performance air filter

[cugir321]

I added a K&N high performance factory type air filter to my 1992 jeep wrangler last week. I was amazed. It dropped my mpg from 17.00 to 11.6mpg. I went back to the cheap standard air filter and today rechecked my milege. 17.25 mpg. This was enlightening. I got more horsepower and it ran more open with the K&N but at a cost. I'm guessing the oxygen sensor saw more oxy and thought it was lean....added more gas!!!!

[dkjones96]

Most likely you were using the little extra power and that caused your mileage drop. Happens all the time. I've got a K&N filter and while i didn't notice a performance or mileage increase it's reusable which reduces my waste.

[cugir321]

No way!!! I drive like an old man. Shift at 2k, turn off engine at red lights, coast in neutral. The filter killed my mpg.. Period! I got the mpg back as soon as I changed it.

Most likely you were using the little extra power and that caused your mileage drop. Happens all the time. I've got a K&N filter and while i didn't notice a performance or mileage increase it's reusable which reduces my waste.

[kamesama980]

the filter was probably over-oiled and the excess got into the air-metering system gumming it up. certainly wouldn't be the first person to have that happen... or the 100th... or the 1000th

[civic_matic_00]

I added a K&N high performance factory type air filter to my 1992 jeep wrangler last week. I was amazed. It dropped my mpg from 17.00 to 11.6mpg. I went back to the cheap standard air filter and today rechecked my milege. 17.25 mpg. This was enlightening. I got more horsepower and it ran more open with the K&N but at a cost. I'm guessing the oxygen sensor saw more oxy and thought it was lean....added more gas!!!!


been using K&N filters on my honda civic and my wife's Toyota Sienna for the past three years. K&N allows for more air flow, and the more airflow the more power but since your engine is getting more air flow it will use more gas to maintain the AF ratio.

you will get more hp but burn more gas in the process. in the past the increase in power is good even if my vehicles burn more gas since gas was cheaper. now a days though the increase in hp is not worth the extra fuel my vehicles are burning. since I am hypermiling and don't use the full power potential of my vehicles anyway, I can make do without the extra hp that the K&N filter adds.

I am thinking about just changing to a regular paper filter and compare the difference in mpg. I am thinking that boosting your ignition system would actually be better than boosting your engine's airflow. a better ignition spark will provide a cleaner fuel burn with the same AF ratio and will deliver better mpg.

I have replaced my civic's sparkplugs with Halo sparkplugs, MPG+ sparkplug wires, and an Accel Supercoil ignition coil. The halo sparkplugs have been in the engine for two weeks and it has been delivering a good FE increase but my full tank of gas only went from 300 miles to around 330 to 340 miles. the MPG + wires actually boosted my mpgs a lot more and before I installed the Accel Supercoil I was getting 350 to 360 miles per tank of gas (that's 10 gallons). I've installed the Accel Supercoil just a couple of days ago and the car has better acceleration AND at only a quarter tank spent I have already gotten 130 miles (that's about 2 gallons or a little over 2 gallons, mostly high way miles though). I can't really get an accurate mpg rating since I don't have a Scangauge yet so I rely on the total miles per full tank.

it is weird that my civic registers more miles for the first half tank than the second half tank. so taking the mpg calculation by the fuel gauge is totally inaccurate for me. I guess my fuel gauge is no longer accurate (probably came from topping off the tank to the max ever since I first bought the car).

I am eagerly anticipating what my total miles would be after this current tank of gas and see what type of gains I've gotten from the combination of the Halo sparkplugs (www.greenplugs.com), MPG+ Sparkplug wires (http://www.increasing-gas-mileage.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=001&Product_Code=6c), and the Accel Supercoil which delivers an extra 10 to 15% power to the spark plugs than OE ignition coils.

after this current tank of gas, I will replace the K&N filter with a paper filter and see if the reduction of air flow to the intakes will boost mpgs better.

[theholycow]

been using K&N filters on my honda civic and my wife's Toyota Sienna for the past three years. K&N allows for more air flow, and the more airflow the more power but since your engine is getting more air flow it will use more gas to maintain the AF ratio.

I think this only matters at high RPM when you're moving a lot of air. I suspect that there's no useful difference between the flow at the low RPMs that hypermilers use.

it is weird that my civic registers more miles for the first half tank than the second half tank. so taking the mpg calculation by the fuel gauge is totally inaccurate for me.

It's quite normal, actually. My brand new VW, which I never top off, does it. Every GM and Ford I've ever driven does it. The only reason I can think of for it is so that they can sell more cars when people say "My behemothmobile gets 200 miles to half a tank with aggressive driving".

[civic_matic_00]

I think this only matters at high RPM when you're moving a lot of air. I suspect that there's no useful difference between the flow at the low RPMs that hypermilers use.

I think you're right. so for hypermilers, there's really no advantage to the much more expensive K&N filter.


It's quite normal, actually. My brand new VW, which I never top off, does it. Every GM and Ford I've ever driven does it. The only reason I can think of for it is so that they can sell more cars when people say "My behemothmobile gets 200 miles to half a tank with aggressive driving".

LOL! that sounds right!

[RoadWarrior]

Yeah I got 150 miles on the first quarter of my 15 gallon tank at the moment, that's 40MPG!!!!!11111

[civic_matic_00]

Yeah I got 150 miles on the first quarter of my 15 gallon tank at the moment, that's 40MPG!!!!!11111

LOL! now that's FE!

[VetteOwner]

I think this only matters at high RPM when you're moving a lot of air. I suspect that there's no useful difference between the flow at the low RPMs that hypermilers use.



It's quite normal, actually. My brand new VW, which I never top off, does it. Every GM and Ford I've ever driven does it. The only reason I can think of for it is so that they can sell more cars when people say "My behemothmobile gets 200 miles to half a tank with aggressive driving".

nah think about it this way: lets take a 20 gal fish tank. perfectly rectangular cut it in half (ie 1/2 a tank) and the shapes and thier volume capacities will be exctly the same.

take a car fuel tank that can look liek a trapezoid, pancake, square top round bottom, etc and im sure most of em when cut horizontally in half do not hold equal volumes (hence one half burns "quicker" than the other half)


i put a K&N alogn with a CAI on my s-10. i noticed a 1-2 mpg gain over the stock maze. most of it was prolly the CAI itself and not the filter (cone filter)

ive had it on for 2 years now so i might swap back to stock and see what it gets then.
it didnt really help performace wise (mayeb high rpm's alogn with the high flow exahust it does) but the normal driving rpm range didnt do anything

[theholycow]

I don't understand the analogy, although I would like to.

The way I see it is this: The manufacturer must design the engine and intake to handle the huge amount of airflow required to make lots of power at high RPM. So, at low RPM, the only restriction in the intake should be the throttle plate, everything else should flow without restricting the air at all. If that's not the case then they've made a huge design flaw.

[GAZH]

I added a K&N filter to my wifes Accord and the mileage dropped about 1.5 mpg. I did add the filter right at the beginning of the summer, so the temperature difference might account for the 1.5 mpg drop. I ran the filter for about 5 months and put the old paper one back in and the mileage went back up. I considering putting it back in after the summer months to see if there really was a difference in filters. I have considered getting a K&N for my Prelude but I dont want to waste money on another one and it doent help the gas mileage. I also have one in my 06 GMC Sierra and the gas mileage increased by 1 mpg. So maybe it has something to do with the bigger engine.

[VetteOwner]

I don't understand the analogy, although I would like to.

The way I see it is this: The manufacturer must design the engine and intake to handle the huge amount of airflow required to make lots of power at high RPM. So, at low RPM, the only restriction in the intake should be the throttle plate, everything else should flow without restricting the air at all. If that's not the case then they've made a huge design flaw.

thats basically it, they help the air flow better at high rpm's. low rpm's the air is moving so slow it doesn't make a difference.

now bigger engines need more air so they might see the difference at a lower rpm range.


heres a pic representation of why the first half of your gastank seems to last alot longer than the 2nd half

http://i141.photobucket.com/albums/r59/Sea_Slugs/My%20Pictures/gastank.jpg

as you can see gastanks can be many shapes, i picked 2 easy ones lol

in the square one the first half of the tank has the exact volume as its 2nd half, meaning the first half will seem to burn the same rate as its 2nd half(same amount of fuel)

in the triangle the first half has alot more volume than its 2nd half so while the first half may last you ohh 200 miles. then once it gets below 1/2 a tank theres alot less volume in the 2nd half so you might only get 100 miles out of it...(hence why it seems your fuel consumption seemingly went really fast)



most trucks have a squareish shape while most cars have some kind of triangular shape or wedge shape so it fits up under the unibody car frame.

[kamesama980]

more air only gets to the engine if you open up the restriction (throttle). every decent study I've seen shows the K&N flows about 1% better and filters 1% worse.

You're also assuming the scale on the gas gauge is linear and accurate. I've driven cars that ran out of gas with the needle 3 of it's width above the E tick mark (my old ford ranger... boy was that an embarrassing discovery). My moms car has 3-4 gallons left when the light comes on and the needle is 3 widths below the mark.

[VetteOwner]

thats also true every single one of those gauges are an estimate (yes including the speedometer)

[dkjones96]

You're also assuming the scale on the gas gauge is linear and accurate. I've driven cars that ran out of gas with the needle 3 of it's width above the E tick mark (my old ford ranger... boy was that an embarrassing discovery). My moms car has 3-4 gallons left when the light comes on and the needle is 3 widths below the mark.

When the needle is at empty on the Tracker it means empty. I've had the needle where it's sitting right in the empty tick and filled up with 17.2 gallons in a 17.5 gallon tank. Making a turn a tad too fast the engine cut out and wanted to die right before the station.

The Cressida, however, used to read 1/4 tank below empty and still have a gallon or two left.

[cugir321]

I don't know about that....I could hear and feel the difference at idle and slow speeds with the K&N filter.

It's a pretty known fact in jeep circles that the 90's wranglers had a poor air feed. I wonder if this had an effect on the amount of mpg loss.


I think this only matters at high RPM when you'r

e moving a lot of air. I suspect that there's no useful difference between the flow at the low RPMs that hypermilers use.



It's quite normal, actually. My brand new VW, which I never top off, does it. Every GM and Ford I've ever driven does it. The only reason I can think of for it is so that they can sell more cars when people say "My behemothmobile gets 200 miles to half a tank with aggressive driving".

[slurp812]

I don't understand the analogy, although I would like to.

The way I see it is this: The manufacturer must design the engine and intake to handle the huge amount of airflow required to make lots of power at high RPM. So, at low RPM, the only restriction in the intake should be the throttle plate, everything else should flow without restricting the air at all. If that's not the case then they've made a huge design flaw.

Paper filters are very effective, and cheap...

[slurp812]

I added a K&N filter to my wifes Accord and the mileage dropped about 1.5 mpg. I did add the filter right at the beginning of the summer, so the temperature difference might account for the 1.5 mpg drop. I ran the filter for about 5 months and put the old paper one back in and the mileage went back up. I considering putting it back in after the summer months to see if there really was a difference in filters. I have considered getting a K&N for my Prelude but I dont want to waste money on another one and it doent help the gas mileage. I also have one in my 06 GMC Sierra and the gas mileage increased by 1 mpg. So maybe it has something to do with the bigger engine.

On my 94 EX Accord, I added a cheapo ebay intake, and then added a one of those chrome straight thru mufflers, and my car got about 2 mpg better! But that was with my foot in it....

[JoeBob]

thats also true every single one of those gauges are an estimate (yes including the speedometer)

Had an '85 Lincoln Continental which had a digital fuel gauge reading in gallons (or liters). It was rarely off by more than about a gallon or so...