[cssnms]

Originally Posted by Snkypete

You want me to post up dyno numbers from the past decade from a dyno I don't even operate any more??? Just so I can "convince" you? Sorry, you're not that important to me.

Believe it or not, even if someone disagrees with you - they may actually know what they're talking about.

Google is your friend - you claim you're smart enough, there's plenty of data out there if you open your eyes. The world doesn't revolve around this manufacturer.

LMAO that is what I thought.

No need to "google" it's all right under your nose.

http://www.e90post.com/forums/showthread.php?t=137667

http://www.bobistheoilguy.com/airfilter/airtest2.htm

"As long as an air filter is properly sized for an application, the lost airflow will be very minimal. This means that there is very little if any power to be found from removing the air filter, much less changing the filter type."

You just keep running those aftermarket air filters for all of those gains you are getting and improved filtration.

Oh and make sure you post up your dyno results after you dyno your car with a clean OEM filter comparing the results against a dyno pull with no filter. Then tell me how your aftermarket filter is going to make more power beyond the differential.

[mlifxs]

Originally Posted by ENINTY

So how do you exactly know you have improved 1.5 MPG on the highway? How have you tracked just your highway mileage MPG?

I keep exact records of all my cars MPG using a book and recording the miles driven and gallons for a complete fill up for every tank of gas (I completely fill the tank every time). I never saw any long term increase in overall average MPG in any car I used a K&N filter in.

There is no benefit to using a K&N. If a manufacturer could magically gain 1.5 MPG (and horsepower) on the highway rating for its cars using a less restrictive filter, it would use that filter as a production part and would make the cleaning of the filter as part of the scheduled maintenance program; especially BMW, which get constantly fined for not meeting U.S. CAFE requirements.

fyi yes hwy mileage. Prior to install I took the time to measure mpg on a specific roadway, cruise control on, air conditioner off. Reset the computer at at a marker on the roadway and noted average mpg at the end point. Did this several times.
Did the same shortly after install. Same conditions. Ambient air temp was very close before and after as was wind speed and direction.

I did the same for my AA tune, measuring before and after.

I don't know if your assertion about the manufacturer is necessarily true. Perhaps it's true in this case (I really don't know, I'm simply passing on my personal experience about a product), but manufacturers do not always optimize performance; sometimes they compromise to meet the preferences of many people in different markets.

[M.Etreby]

I belive my question now would be after i read it all, why do BMW install K&N air filters in their perfomance air intakes and claim an increase in HP as well as torque?

[spacemonkey1112]

Originally Posted by Snkypete

The operative word, both times you have posted it, is MOST.

I have seen cars gain 15-20whp with a change, and that was not 1-2%. I do agree that most of their claims are inflated as are most aftermarket accessory companies.

While I would have preferred a nanofiber filter, unfortunately one doesn't exist. I could have created a DCI setup like this but again that wasn't what I wanted for this vehicle.

15whp change from an intake only happens in forza. yes there are upgrades that can give you that kind of power; but not from a 40 dollar filter.

what you'll get from a k&n is a little more responsive throttle and a more pleasing (but only slight change) in sound.

[ENINTY]

Originally Posted by mlifxs

fyi yes hwy mileage. Prior to install I took the time to measure mpg on a specific roadway, cruise control on, air conditioner off. Reset the computer at at a marker on the roadway and noted average mpg at the end point. Did this several times.
Did the same shortly after install. Same conditions. Ambient air temp was very close before and after as was wind speed and direction.

I did the same for my AA tune, measuring before and after.

I don't know if your assertion about the manufacturer is necessarily true. Perhaps it's true in this case (I really don't know, I'm simply passing on my personal experience about a product), but manufacturers do not always optimize performance; sometimes they compromise to meet the preferences of many people in different markets.

Well although you tried to keep the test conditions the same, your increase in MPG is not a result of a true scientific test. You cannot exactly duplicate the engine load and % throttle position on every test run. I’m not saying you are being dishonest about it, I’m just saying you don’t have enough data to absolutely state the filter improves gas mileage.

It's been my experience after keeping strict MPG records for all my cars for the past 20 years or so, that the average MPG per tank varies by more than 1.5 MPG. When I fill my E90 up at the same gas station and same fuel pump (every two days) and then drive unobstructed on a rural 55 MPH highway (not an interstate), my MPG reading from the BC (after resetting it to zero upon fill up before I restart the engine) starts out low, then slowly climbs to over 34 MPG then backs down to around 28 (using numbers just for example). So resetting the BC to get a MPG reading is not an accurate measurement to ascertain the precision of 1.5 MPG.

Using my data of average MPG per tank over hundreds of fill ups before and after installation of a K&N filter on three of the five vehicles I installed a K&N filter (for my wife’s cars I don’t keep gas fill up data), I never saw a discernable upward trend in average per-tank MPG. The vehicles were a 1989 E30, 1999 F-150, and a 1999 Honda Valkyrie Interstate.

[mlifxs]

Originally Posted by ENINTY

Well although you tried to keep the test conditions the same, your increase in MPG is not a result of a true scientific test. You cannot exactly duplicate the engine load and % throttle position on every test run. I’m not saying you are being dishonest about it, I’m just saying you don’t have enough data to absolutely state the filter improves gas mileage.

It's been my experience after keeping strict MPG records for all my cars for the past 20 years or so, that the average MPG per tank varies by more than 1.5 MPG. When I fill my E90 up at the same gas station and same fuel pump (every two days) and then drive unobstructed on a rural 55 MPH highway (not an interstate), my MPG reading from the BC (after resetting it to zero upon fill up before I restart the engine) starts out low, then slowly climbs to over 34 MPG then backs down to around 28 (using numbers just for example). So resetting the BC to get a MPG reading is not an accurate measurement to ascertain the precision of 1.5 MPG.

Using my data of average MPG per tank over hundreds of fill ups before and after installation of a K&N filter on three of the five vehicles I installed a K&N filter (for my wife’s cars I don’t keep gas fill up data), I never saw a discernable upward trend in average per-tank MPG. The vehicles were a 1989 E30, 1999 F-150, and a 1999 Honda Valkyrie Interstate.

you are correct that I cannot say with absolute certainty that my measurement / "controlled experiment" is true. There could be other unknown factors in play. Note that it is also possible that unknown factors could skew my results lower. instead of higher. There's really no way to tell and I'm only willing to go far to reach conclusion on a $40 air filter

I'm responding to an OP who asked for input by sharing my personal experience.

[mlifxs]

Originally Posted by ENINTY

Well although you tried to keep the test conditions the same, your increase in MPG is not a result of a true scientific test. You cannot exactly duplicate the engine load and % throttle position on every test run. I’m not saying you are being dishonest about it, I’m just saying you don’t have enough data to absolutely state the filter improves gas mileage.

It's been my experience after keeping strict MPG records for all my cars for the past 20 years or so, that the average MPG per tank varies by more than 1.5 MPG. When I fill my E90 up at the same gas station and same fuel pump (every two days) and then drive unobstructed on a rural 55 MPH highway (not an interstate), my MPG reading from the BC (after resetting it to zero upon fill up before I restart the engine) starts out low, then slowly climbs to over 34 MPG then backs down to around 28 (using numbers just for example). So resetting the BC to get a MPG reading is not an accurate measurement to ascertain the precision of 1.5 MPG.

Using my data of average MPG per tank over hundreds of fill ups before and after installation of a K&N filter on three of the five vehicles I installed a K&N filter (for my wife’s cars I don’t keep gas fill up data), I never saw a discernable upward trend in average per-tank MPG. The vehicles were a 1989 E30, 1999 F-150, and a 1999 Honda Valkyrie Interstate.

Entity to be fair to you and the op it is worth mentioning that, per my orig response that I did the charcoal delete as well. So, you could be right about K&N filters and I could still be seeing a genuine improvement in hwy mpg due to the charcoal delete .... I did not isolate each in my testing. I don't know of course but it seems plausible that removing the charcoal filter is improving airflow in a beneficial way.

[ENINTY]

Originally Posted by mlifxs

Entity to be fair to you and the op it is worth mentioning that, per my orig response that I did the charcoal delete as well. So, you could be right about K&N filters and I could still be seeing a genuine improvement in hwy mpg due to the charcoal delete .... I did not isolate each in my testing. I don't know of course but it seems plausible that removing the charcoal filter is improving airflow in a beneficial way.

Maybe. I'm not even sure why there is a charcoal filter past the airfilter element anyway. Seems to be BMW over-engineering to me. What I don't understand is what benefit the charcoal filter provides that it's worth sacrificing 1.5 (or any amount) of MPG. Considering BMW has one of the worst records meeting US CAFE requirements, they'd not put anything in the intake path that would restrict airflow and MPG. I'm assuming the charcoal filter is there to double clean the already filtered air to protect vital sensors in the intake tract. I've not wanted to remove the charcoal filter once I discovered it was there simply for fear of causing drivability issues.

It's good that you have been taking a somewhat scientific method to determining if the K&N adds benefit to the performance of the car (acceleration and/or MPG). Other than straight dyno runs on both filters on the same day can any appreciable determination be made.

[benzo23]

Holy shit you guys are beating a dead horse with this one. Who really cares about a 1.5 mpg increase. Just stick with oem filters and lets end this damn thread. It will only be about another week before someone else brings this up anyways lol

[neilyo]

Good tutorial man. Thanks.