KN finally released a drop in filter for the 2013 V6. I put one in my EXL and without the ECO mode on the car delivers smoother acceleration, runs smoother when 3 cyl are deactivated. In addition the highway mileage has peaked out at 38.5 running a steady 5 miles over. These filters have served me well for all my cars for over 20 years. Honda should make them OEM!

 

Sorry, not possible. Regardless of whether you're running a factory air filter element, a K&N, or no filter at all, your fuel economy CANNOT change either way. As for how the engine runs; ever heard of the placebo effect? All your aftermarket filter is doing is allowing lots of extra dirt into your engine and accelerating engine wear.

The fact is, the OEM style filter used by Honda (and virtually every other manufacturer) is superior in every way to the K&N in your car.

 

Believe it or not the mileage is observed on the same trip under the same conditions. Pure highway run on divided 4 lane. As to the performance, it is common knowledge that an unstopped nose breaths better. The engine runs smoother on light acceleration. I put 170,000 trouble free miles on a 4Runner with a KN filter and the mileage on it improved also.

 

In most instances when it comes to automotive "knowledge", Common Knowledge = Urban Legend

Just because something is "common knowledge" doesn't in any way mean it is correct.

If you opt not to believe anything I've written, cool, I have no problem with that, however, I would strongly suggest you do a little studying on your own. Here is a good place to start:

• http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

 

Okay, so I read the above document. It 'was an interesting read. I am not "arguing", but I did want to point out something.

You stated that there was a performance "placebo effect", but indeed, the analysis provided by the link above stated there was defiantly a measurable effect on power when the air filter was clogged.

From what I can tell, the city fuel economy test does not include defined acceleration time parameter minimums, only maximums. Meaning, the test says, accelerate to X miles an hour, then decelerate to x mph, repeat. There is no requirement the accelerationtake place in a specific distance, only over a specific distance.

When you and I drive a car, we might depress the accelerator hard enough to accelerate a rate we are comfortable with. If an air filter is clogged, we may need to depress the accelerator more, to attain that same level of acceleration (butt dyno if you will). We could also be gauging our acceleration rate on other traffic. Given this, you could see a decrease in miles driven per take not due to the clogged filters effect efficiency, but due to the increased throttle application to get a similar response from the vehicle.

In short, clogged filter = less HP (indisputable), less HP leads to less acceleration at a given throttle setting. Greater throttle application means more fuel required to attain and maintain a given speed.

In conclusion, a dirty air filter will lower measured fuel economy (miles per tank) if acceleration rate is considered into the equation.

 

Yes, a heavily clogged (as in way more clogged than even 100,000 miles of normal driving would cause) air filter will reduce horsepower, however, the difference between a clean OEM style filter, an aftermarket low restriction filter, and no filter at all is virtually immesurable.

Incorrect, it will *IMPROVE* measured fuel economy.

 

Fair enough...

How so? If I have to push the accelerator 50% to get to 60 mph in 20 seconds with a clean air filter (I am making this up) , and I have to depress the throttle 60% with a dirty air filter to get to 60 mph in 20 seconds (again, made up numbers for illustration), because the reduction in HP from the restriction has cause me to increase throttle to get the same acceleration as with a clean filter, how is it my MPG will "improve"?

Again, I am not arguing, I am merely looking for you to set me straight with something more than a disagreement.

 

In your two above 60 mph in 20 seconds scenarios, the fuel economy will not change either way, however, per the study, in cases where the air filter is so extremely clogged the car would take more like 25 seconds at WOT to make it up to 60, the fuel economy will improve a bit (a very small bit) because power required for the slower acceleration will be a bit lower. Think about it this way:

• Scenario 1: A car accelerates to 60 in 20 seconds, and then maintains that exact speed to a point 1 mile from where it started moving.
• Scenario 2: The above car, now with a heavily clogged air filter, accelerates to 60 in 25 seconds and then maintains that exact speed for a point 1 mile from where it started moving.
• Result: The car in Scenario 1, by virture of its greater acceleration (and fuel requirements), used more fuel to transit that mile than the car Scenario 2.

You probably already know this, but to others less versed on how modern fuel injection systems operate, I think the above requires a bit more explanation.

Fact: A 60% throttle plate setting does not equate to a 60% fuel setting. The computers which control the fuel system on pretty much all cars determine the *weight* of the intake charge and meters out only the necessary fuel for the amount of air coming into the engine; said computers really don't care what the throttle setting is (except for idle and WOT which is a different discussion).

So, given that it take more fuel to accelerate to 60 in 20 seconds than for tha same car to accelerate to 60 in 25 seconds, a heavily clogged air filter can actually improve fuel economy.

Reality: After turning a wrench (first professionally and then as a hobby after I became an engineer), I'd guess fewer than two or three percent of the cars on the road have an air filter so clogged it will make a significant difference in time to speed acceleration numbers.

 

Ok, I think I am catching what your throwing...

Using my example, 0 to 60 in 20 seconds with/without clogged AF, the volume of air is the same to get the same HP, so since it's the same, and the A/F mixture is fixed, the fuel used per mile is identical... I can agree with that. You made me think a little...

Putting it all together, Modern F/I is constantly altering fuel based on actual air available which is related to throttle setting (MAF), air density (MAP), O2 and temp. A clogged A/F feeds less fuel to compensate for the lower amount of air. You may be able to detect the performance hit, but likely only when the A/F is almost completely restricted.

The effects of air filter restriction would be more evident in an older carbureted engine where A/F mixture is fixed as it's based on jets. Cars built before 81 may fall into this category, but not after.

Any performance gain with performance filters is likely negligible, and within any variance of a test device (dyno).

I agree with your assessment on this point.

Thanks for walking through this. Had to put on my thinking cap and noodle it a bit.

 

Yeah, carbureted engines were a whole different ball game, and are the source of many-many misconceptions on how modern cars operate.

It's starting to sound like we're singing from the same page of the hymn book; scary thought!