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Early K&N vs OEM Filter Results

24K views 38 replies 18 participants last post by  diamondlarry 
#1 ·
Alright, I know there's ALWAYS a ton of debate/discussion around performance air filters, but I've got some results that I'd never have expected, so I thought you all might enjoy hearing about it.

I pulled out the OEM air filter and decided I didn't like it at all; it looked cheap, felt cheap, it's like an air intake tampon. I was displeased. I decided to buy a K&N filter from Amazon because it was about $10 cheaper than through my local parts store, even with next day air, so I jumped on it. I swapped out the filters, threw the OEM filter next to the spare tire for the inevitable 24 hour cleaning the K&N will need, and did some driving.

Here's the deal: I'm using stats from the last tank of gas; I've only burned part of the tank since the K&N filter, drove the same routes using the same driving style, the CC is not on. Here's what my early results are showing:

Tank average with OEM filter: 47 mpg.
Real-time fuel economy cruising (rough average): ~51 mpg

Current tank average with K&N filter: 51 mpg.
Real-time fuel economy cruising (rough average): ~65 mpg

It's still early in the tank, but I haven't gotten these numbers consistently out of this car during in town drives, so this is a major improvement. Once I'm further into the tank, I'll update this number.
 
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#2 ·
Just for grins.....after this tank is done, put the OEM back in just to make sure your MPG goes down again.....The reason I suggest this.....there may be other factors involved in your recent higher MPG

Warmer weather is always a positive towards higher MPG....
Driver getting more experince with achieving higher numbers may also be a factor.

I'm not saying the K&N is no good but like with any test or troubleshooting, you should be able to produce predictable results and if you don't try it, you will never know if other factors were involved.

JoeCVT = Just your average CVT owner
 
#4 ·
Interesting.... I am tempted to try cleaning mines or try a standard filter again.

I found with my super charged tacoma I was cleaning the red filter that turned black after 2 thousand miles of use always gave a bit more performance for a few weeks til it blacked up again. I could hit 15 vs 13 psi of boost too with a fresh cleaning.
 
#5 ·
Why the heck do these K&N filter discussions pop up on every automotive forum known to man! Surely with a car as complex as the Insight, the air filter makes little difference! Heck, try running the car for one tank without an air filter at all! You should see better improvement versus the K&N, right?
 
#7 ·
Why the heck do these K&N filter discussions pop up on every automotive forum known to man!
Automotive Forum. That's a major contributor to the problem. Automotive forums have a tendency to be infiltrated by tech-savvy motorheads who love nothing more than big block V8's stuffed under the hood of an El Camino or Catalina just to hear it roar and visit every gas station in town.

Those guys tend to be obsessed with performance parts, like the K&N filter. The reason the air filters come up so often is because they make them for virtually everything. Not many people will be looking for new headers for their Insight, but everyone replaces the air filter at some point...and that's the appeal: it's easily accessible and it's a part associated with better performance.
 
#11 ·
Two problems here:

1. I'm not doctoring my math or changing my driving habits. It's just the number I'm getting off the dash.

2. I don't think computers are susceptible to a placebo effect, but I'll start telling my Honda that it has a paper air filter in it, just in case.
 
#10 ·
I think we should break into these people's cars, replace their K&N filters with stock ones without telling them, and then come back on the forum. I bet you they will still be singing the praises of their increased gas mileage with the K&N filters... with a stock paper filter.
 
#12 ·
I bet you they will still be singing the praises of their increased gas mileage with the K&N filters... with a stock paper filter.
That's not exactly what I started here, I was just remarking on an anomaly in my fuel economy immediately after having changed the air filter. I don't see any reason to knock the guys who claim to get better fuel economy out of it, though, because it's plausible under the right conditions.

Alright, I know there's ALWAYS a ton of debate/discussion around performance air filters, but I've got some results that I'd never have expected, so I thought you all might enjoy hearing about it...


...It's still early in the tank, but I haven't gotten these numbers consistently out of this car during in town drives, so this is a major improvement. Once I'm further into the tank, I'll update this number.
 
#15 ·
My use of kn has never resulted in more mpg, just more power/noise.

Likewise I find more mpg with econ on vs off. Some find just the reverse.

On one forum I read where use of a kn filter was wasnt oiled properly can result in the car running lean as the oil vapor fouls the sensor.
 
#16 ·
According the EPA website they ran a test on air filters and concluded that even a severely clogged air filter had no effect whatsoever on MPG. Pretty conclusive. Here's the link to the study:

http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf

Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a decrease in fuel economy with increasing restriction. However, the level of restriction required to cause a substantial (10–15%) decrease in fuel economy (such as that cited in the literature 3,4) was so severe that the vehicle was almost undrivable. Acceleration performance on all vehicles was improved with a clean air filter.
 
#17 ·
Alright, final number on that tank was 51 mpg and a little bit of change.

I've been driving through the mountains (and a little aimless driving around Richmond looking for a restaurant that doesn't exist anymore on my way back home) and on this tank I'm averaging a little over 48 mpg.

If this car doesn't end up breaking 50 consistently, I'm going to be sorely disappointed. It's got every bit of the potential to take Toyota's cake and eat it, too. Have you noticed the differences between user reported MPG on fueleconomy.gov? The I2 has been giving the Prius a run for its money.
 
#19 ·
I'm actually with ackattacker here, I don't suspect there'll be a statistically significant difference in fuel economy between the two (though I can admit to noticing a very small difference in power when the pedal is on the floor). I think the gradual increase I'm seeing in fuel economy can be attributed entirely to the wear in period. I'm around 3500 miles now (man, I'm just racking up the milesand I've seen an improvement on each fill up (excepting my regular trips into the hills).

It'll be difficult to get accurate fuel economy estimates out of the two because I took a road trip to Harrisonburg, VA on the last trip, which meant a significant amount of mountainous driving.
 
#20 ·
K&N is nice but not for the mpg.

It's true about the filter not making a difference in mpg. Modern cars operate with a mass air flow sensor which measures how much air it's able to get in the intake so that it can compensate with more or less fuel to get the proper air to fuel ratio. It really only mattered on older carborated cars which had no idea if the filter was clogged and dumped the same amount of fuel as if it wasn't. I'm not saying it's not economical to buy K&N, I swear by it, all our cars run them. But I buy them because they're washable, so by the second time you wash it, it has paid for itself and from then on it just savings. The other reason is they're made in America, I'm all about supporting 'made and sold by american'.
 
#23 ·
That's a funny statement. Honda is made where???? Yeah, that $40 K&N sure helped our economy! Good thing you "buy American"!
Companies having plants in America are a positive thing. It boosts the local economy. Local people get employment. The state, city / local government get to receive taxes, and the Feds as well.

The final destination of the money may be sent abroad outside of the USA, but not without the USA getting its fair share.

It's different than just importing things completely manufactured outside of the USA.

But if you're specifically talking about the Japan-Made Insight (Honda J-VIN automobile,) then I can understand what you said.
 
#22 ·
EricQ:
Not all modern cars use a MAF sensor. MAP is used in some, includeing the !st gen Insight. Don't know about the 2nd Gen. though.
An engine can be tuned to use either. (Most require a different map in the ECU) My experienece.
Willie
 
#28 ·
Alright, I've burned through a few tanks of gas and here's what I've got so far:

As suspected, the OEM filter is roughly equal to a K&N filter. Being in Virginia means the weather's all over the place right now and that impacts fuel economy pretty substantially. I've also got only about 3,800 miles on the car now, so I'm still well within the forum reported mpg break in period. I've had to "guestimate" the effects of temperature, barometric pressure, humidity, etc on fuel economy, so there's a 100% chance I'm wrong about the actual outcomes. The EPA did this in a lab environment; it would be more accurate for all the obvious reasons.

Anyway, I've been able to hold fuel economy just shy of 51 mpg on this tank. The previous tank was around 48-49, but it was colder and we had more rain while I was running that tank; I suspect we're starting to see summer fuel mixes now, too, but I'm not sure. There are just entirely too many variables to attribute any fuel economy increases to the air filter alone. I was hoping for a few days of similar weather, but that's just not going to happen this time of year.
 
#34 ·
There are just entirely too many variables to attribute any fuel economy increases to the air filter alone.
+1
Really no difference is power or mileage. The one concern I had is that there was always a coating of really light dust in the lid of the air box and into the air mass meter with the K&N. Not there with the OE filter.
+1
He said he had proof that it wasn't good enough at actually performing its primary role, that of filtering air. He also questioned why I would think they could design the part better than BMW.
+1

No two trips will be identical, and so it will be very difficult to measure any meaningful differences. The K&N filter's ping-pong ball test display looks convincing on the countertop at the parts store though! :)

Another suspect mileage improvement gadget to me is the radiator block. Many people swear by "10% or more MPG gains". I have not seen it - but YMMV :)

One great MPG test was posted about the Re92 Gen 1 OEM tires vs Ecopia (?) tires performed back to back on same stretch of road at same speeds/rpm with careful weather/wind condition measurements also reported. (With surprising results.)
 
#29 ·
Yeah, it would be really hard to say. Thanks for the review. I had a K&N on my TDI Jetta for a while. Really no difference is power or mileage. The one concern I had is that there was always a coating of really light dust in the lid of the air box and into the air mass meter with the K&N. Not there with the OE filter. It was enough of concern that I quit running the K&N. Just something you might keep an eye on.
 
#30 ·
K&N

I understand the reasons for using the K&N, and I think I still have one in my Silverado, but the first time I took my old 325i to my highly qualified (non-dealer) mechanic he disposed of my K&N and installed an OEM part. He said he had proof that it wasn't good enough at actually performing its primary role, that of filtering air. He also questioned why I would think they could design the part better than BMW. I think the same would be true for Honda. I'm referring to performance and durability, not sound. As usual, just my two cents.
 
#32 ·
I don't think it will help with fuel economy but it may help a little with power.
This is my experience with performance air filters:
I have a 2008 smart and compared the OEM paper filter against a BPP performance drop-in filter at the 1/4 mile. (BPP is very similar to the K&N version)(Both filters where clean and new the day of the test)
I swapped back and forth several times and the BPP helped reduce the 1/4 mile elapsed time by .2 seconds after I averaged the times for all runs.
I still have the car and never could tell if it helped with fuel economy.
Keep in mind that the filters for the smart and g1 Insight are very similar in size and they both produce about 70hp on one liter 3's. Gerbil power! :D
 
#36 · (Edited)
The swearing post has been removed and so have the follow ups, as without the offensive original post they make no sense. Peter

Edit Viper login Banned
 
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