Which obtains better MPG: K & N or paper filter?

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calvin1- I knew you made a joke and I just continued the joke about Toyota. Maybe they just rigged the throttles to stick to save fuel.

I first heard about the dang throttle plate impairing efficiency in my power mechanics class in high school in 1971.

Surprising nobody has come up with a way to get rid of it.

I get better fuel mileage when I drive in the mountains and I wonder if the wider throttle settings improve efficiency when going uphill.
 
Originally Posted By: ledslinger
calvin1- I knew you made a joke and I just continued the joke about Toyota. Maybe they just rigged the throttles to stick to save fuel.

I first heard about the dang throttle plate impairing efficiency in my power mechanics class in high school in 1971.

Surprising nobody has come up with a way to get rid of it.

I get better fuel mileage when I drive in the mountains and I wonder if the wider throttle settings improve efficiency when going uphill.


lol, sorry, sometimes it's hard to tell the jokes from the real stupid. Actually, IIRC Mercedes has a variable valve system that goes to WOT and switches to using valve lift at cruise for throttle control. Of course it needs the dreaded drive-by-wire to get that control of the throttle plate in the first place but it's kinda cool. They get some efficiency gain but nothing crazy.
 
calvin, the fuel maps are not as precise as you imply and there are more than just O2 and MAF parameters that go into it, but regardless, by your logic, simply restricting air intake = better mpg.

which means you probably disagree that a better flowing intake and exhaust would also decrease mpg. but these things can increase torque for the same gasoline used. that does = better mpg.

and i think we can agree that at low rpms there's practically no difference between the paper and K&N. which brings us back to the right foot controlling it
 
Yep, BMW have the Valvetronic system in their superb 4-cyl gasoline engines which handles all throttling - I don't think you get those engines in NA models.

You really have to admire K&N marketing - but not their air filter products.
 
I've had K&N air filters in 4 vehicles and I have never measured any difference in mpg, ever, not no way, not no how! ATMOF, I don't notice/feel any difference in power or throttle responce either.
 
Originally Posted By: ledslinger
You know what really keeps my engine from breathing easier? The throttle plate! I bet if I wired the throttle wide open I'd get great gas mileage!

Are you a Toyota engineer?


LOL That's a good one.

Originally Posted By: calvin1
Originally Posted By: daman
Well K&N is suppose to be, they let more air in thus easer breathing,but you know the down side to the ol stone catcher is.


You know what really keeps my engine from breathing easier? The throttle plate! I bet if I wired the throttle wide open I'd get great gas mileage!


In reality naaahh. Because it would mean the engine is running at full speed all the time. This I think is one of the reasons diesels are so much more efficient. They have free flowing intakes, and vary speed by injecting different amounts of fuel depending on the throttle pedal position.
 
i went from paper to paper oem -> aem dryflow and gained about 2-3mpg. normally went 350 to the tank, now i get 370-400. not [censored]'ing....i couldnt believe it myself. could probably be the intake itself...
 
Far more important reasons are that the expansion ratio is significantly higher and there are less pumping losses at part load.
 
Originally Posted By: Kiwi_ME
Far more important reasons are that the expansion ratio is significantly higher and there are less pumping losses at part load.


Expansion ratio and energy content seem close. There is about 13% more energy in a gallon of diesel than a gallon of gasoline. Expansion ratio prolly is the bigger one though.

I haven't seen pumping losses quantified but suspect they are in 3rd place.
 
Depends on driving conditions and how heavy your foot tends to be...

In my truck - on the highway at cruising speed, K&N-type tends to get marginally better mileage.

Around town there isn't much difference, except I tend to accelerate faster when using my K&N.

In all honesty, I pulled the K&N out and switched back to paper because I hear that K&Ns let more dirt through, hence can increase engine wear. I almost never use the K&N anymore.

IMO if you buy a K&N to increase your mileage you will be disappointed. If you buy a K&N to increase throttle response (and to a lesser extent, horsepower), then you'll be happy.
 
My AEM CAI Dryflow Filter returned better silicon results on my UOA versus the OEM paper filter, along with AFE Dry Flow Panel Filter...

For that alone, along with slightly better top-end power, I am happy.

Plus it sounds good :D
 
Originally Posted By: calvin1
Originally Posted By: daman
Well K&N is suppose to be, they let more air in thus easer breathing,but you know the down side to the ol stone catcher is.


You know what really keeps my engine from breathing easier? The throttle plate! I bet if I wired the throttle wide open I'd get great gas mileage!


I love your responses! Finally someone who thinks like me.

Seriously guys, how many times does this have to be said. I've even linked to the govenment study on this. More air= more fuel being used. Less air = less fuel.

The throttle plate is the largest restriction. If the other logic were true, cars would get their best mileage at wide open throttle.
 
Originally Posted By: [RT
ProjUltraZ]calvin, the fuel maps are not as precise as you imply and there are more than just O2 and MAF parameters that go into it, but regardless, by your logic, simply restricting air intake = better mpg.

which means you probably disagree that a better flowing intake and exhaust would also decrease mpg. but these things can increase torque for the same gasoline used. that does = better mpg.

and i think we can agree that at low rpms there's practically no difference between the paper and K&N. which brings us back to the right foot controlling it


You leave out that the engine is not throttled with exhaust. The easier it is to get the exhaust out, the better mileage it's going to get of course. Intake is different. You free up the intake, you make more power, you use more fuel whether this is done via the filter or your right foot.

There is no difference as far as mpg is concerned whether the additional air comes from an open throttle plate or a less restrictive filter. No difference. So why would you somehow get better mileage with a freer flowing filter?
 
There is no difference as far as mpg is concerned whether the additional air comes from an open throttle plate or a less restrictive filter. No difference. So why would you somehow get better mileage with a freer flowing filte?

A variable restriction filter would eliminate the need for a throttle plate.

Just kidding, but that is a good way of looking at it.
 
Originally Posted By: BuickGN
There is no difference as far as mpg is concerned whether the additional air comes from an open throttle plate or a less restrictive filter. No difference. So why would you somehow get better mileage with a freer flowing filter?


that makes sense, but would you automatically get better mpg by restricting the air filter? anyone can try this, just wrap plastic around half or more of your air filter. if the PCM can adjust fuel delivery w/ the MAF sensing less air, but disregaring the throttle position sensor is not less, and all the feedback from the various sensors, whats in the fuel maps, who knows what else....i'm not sure it would work w/o a PCM reprog

but what a way to live, just trade in for a honda civic or a prius or something
 
Originally Posted By: BuickGN

Seriously guys, how many times does this have to be said. I've even linked to the govenment study on this. More air= more fuel being used. Less air = less fuel.

The throttle plate is the largest restriction. If the other logic were true, cars would get their best mileage at wide open throttle.


The fact is, if you want to make your car do a steady 60 MPH down the road it's going to take XX HP to do so. XX HP is achieved by burning a specific amount of air + fuel mixture. FI engines control the AF via O2 sensor feedback when cursing steady-state and in closed-loop mode.

Therefore, if an air filter is more restrictive from being dirty, it's just going to take a hair more throttle to achieve that 60 MPH HP level.

The only time you could probably see a difference on any engine (FI or not) is at WOT because then the reduction of air flow rate (from a dirty filter) would be evident because you can't compensate with any more throttle beyond WOT.
 
Posters keep mentioning the fuel maps. Those are only used in open loop. An EFI system is going to be in open loop from crank until the O2 sensor is hot (heated ones can be ready in a few seconds) and at WOT. Besides those few times it will be in closed loop where the fuel maps aren't being used and trim is adjusted based on the O2 sensor signal instead.
 
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