Went back to stock

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Open intakes are really for noise/looks - a proper closed air box bringing in outside "cold" air is the best but I argue running a K&N or other high-flow filter (can be dry media for all I care) is a great DD mod (will give a touch louder intake note and flow better) for folks in areas that aren't seeing huge particulate issues in the air they drive through. I also think that when a vehicle is moving at speed through the air the IAT is going to be about teh same between an open or closed intake. Also, no shocker on the MAF...that's the great urban legend of the oil coming off the K&N ruining them...it's B.S. Watch this video...some interesting testing they did (yes, I know it's by K&N so if you are a conspiracy theorist..move along)...I think it's quite interesting.

https://www.youtube.com/watch?v=gE6moItrZNg&t=892s
 
The myths swing both ways on K&N.

It's the facts of K&N that are more relevant.

K&N uses 2 more layers of cotton gauze for their diesel truck filters than they do for passenger cars.

For off-road and dirty areas, K&N recommends the use of a foam pre-filter.

K&N themselves after Arlen Spicer's visit to K&N admitted outright that their filter was a compromise between flow and filtration. (But don't admit that in advertising)

K&N also admitted that their efficiency figures are based on testing using constant and not variable dust loading and admitted their filters don't fare as well during a variable loading test. (But don't admit that in advertising)

As I have said many times before, K&N air filters are a valid product with a valid application. K&Ns only crimes are misrepresentation by omission, and recommending products for inappropriate applications.
 
Originally Posted by DoubleWasp
The myths swing both ways on K&N.

It's the facts of K&N that are more relevant.

K&N uses 2 more layers of cotton gauze for their diesel truck filters than they do for passenger cars.

For off-road and dirty areas, K&N recommends the use of a foam pre-filter.

K&N themselves after Arlen Spicer's visit to K&N admitted outright that their filter was a compromise between flow and filtration. (But don't admit that in advertising)

K&N also admitted that their efficiency figures are based on testing using constant and not variable dust loading and admitted their filters don't fare as well during a variable loading test. (But don't admit that in advertising)

As I have said many times before, K&N air filters are a valid product with a valid application. K&Ns only crimes are misrepresentation by omission, and recommending products for inappropriate applications.



I guess the "admitted outright that their filter was a compromise between flow and filtration" is a duh to me - of course! The issue to me w/r to K&N or any other high-flow filters is this...does you car need an extra X% of filtering efficiency? Does that X% make any meaningful difference? In the K&N testing (Spicer) that is so famous on the interwebs, the difference is about 3% if I am remembering correctly (96% for K&N and 99% for all the paper ones with AC Delco being highest?). And that graph was quite misleading as th axis started at 90% (again, from memory here) so tha the K&N looked way worse than the others. Last UOA I did on my Golf running a K&N had the comment "excellent filtration" based on low Si and other numbers - not everyone has issues with these. K&N produces an after-market performance product and like all of these companies, markets it accordingly.
 
Originally Posted by DoubleWasp


It's the facts of K&N that are more relevant.

K&Ns only crimes are misrepresentation by omission, and recommending products for inappropriate applications.



You sound like a K&N supporter. Do you view these "crimes" as minor?

Credit where due, K&N has thrived for a long time on solid marketing.
 
Originally Posted by TiGeo
Originally Posted by DoubleWasp
The myths swing both ways on K&N.

It's the facts of K&N that are more relevant.

K&N uses 2 more layers of cotton gauze for their diesel truck filters than they do for passenger cars.

For off-road and dirty areas, K&N recommends the use of a foam pre-filter.

K&N themselves after Arlen Spicer's visit to K&N admitted outright that their filter was a compromise between flow and filtration. (But don't admit that in advertising)

K&N also admitted that their efficiency figures are based on testing using constant and not variable dust loading and admitted their filters don't fare as well during a variable loading test. (But don't admit that in advertising)

As I have said many times before, K&N air filters are a valid product with a valid application. K&Ns only crimes are misrepresentation by omission, and recommending products for inappropriate applications.



I guess the "admitted outright that their filter was a compromise between flow and filtration" is a duh to me - of course! The issue to me w/r to K&N or any other high-flow filters is this...does you car need an extra X% of filtering efficiency? Does that X% make any meaningful difference? In the K&N testing (Spicer) that is so famous on the interwebs, the difference is about 3% if I am remembering correctly (96% for K&N and 99% for all the paper ones with AC Delco being highest?). And that graph was quite misleading as th axis started at 90% (again, from memory here) so tha the K&N looked way worse than the others. Last UOA I did on my Golf running a K&N had the comment "excellent filtration" based on low Si and other numbers - not everyone has issues with these. K&N produces an after-market performance product and like all of these companies, markets it accordingly.


Percentages are also misleading, especially in a narrow range.

A percentage point can represent multiplication. In the case of K&N, if we forget the percentage point completely, we find that it allowed 18 times more dirt than the AC Delco filter.

There, the "percentage system" was far far far more charitable to K&N than the actual dirt passage figure revealed. This is why I don't understand people getting mad over the percentage figure. That figure is doing K&N the most favors, making the dirt passage sound small by comparison.

I'd rather hear "3% worse" than "18 times worse" any day of the week if I were them.

And let's keep in mind that this is their 7-layer media that let 18 times more dirt through. How much worse do you think the media is with only 5 layers?

All this is going on is a very gentle test. In the real world, things get quite nastier. This is how I have ended up seeing so many K&N filters in front of some very dirty intake tracts.

I understand that Blackstone told you "excellent filtration", but Blackstone will say that for any engine with low Si numbers. They've said that for marine UOAs I have sent in. Do boats have "excellent filtration"? No. They don't. I can put a full strip of paper right through a marine flame arrestor. If I poured sand on the flame arrestor of some of them, I bet I could get every grain through without making a mess before the engine blew up. Metal slats or tremendously spaced screens.

It's not "excellent filtration" it is "favorable conditions". Your Golf is an on-road vehicle that likely does not exist in a harsh environment. The truth of the matter is your vehicle is likely benefitting from both filtration and favorable conditions.

Is it really obvious that a performance filter is a compromise? Most K&N buyers barely know what an air filter is, and K&N isn't telling them any better, so how would it be obvious?

Does a vehicle need "X filtration"? Some do. K&N will literally sell you one for anything at all. The point is that K&N could care less what your filtration needs are or are not. They're going to sell you one anyway.

Coming back to the metal flame arrestors, I actually replaced all of mine with K&N filters. Why? Any cotton gauze beats that junk, and K&N media is a USCG certified flame arrestor. Perfect application for K&N.

K&N does NOT market their filters accordingly to the fact that their filters are a compromise. That information is NOWHERE in their advertising. They even used to market fuel economy benefits, which is complete horse manure, and no longer do.

They are an entire species of gorillas when it comes to marketing, but it is not at all accurate.
 
Originally Posted by AZjeff
Originally Posted by DoubleWasp


It's the facts of K&N that are more relevant.

K&Ns only crimes are misrepresentation by omission, and recommending products for inappropriate applications.



You sound like a K&N supporter. Do you view these "crimes" as minor?

Credit where due, K&N has thrived for a long time on solid marketing.



Lol. Anyone here can tell you I am far from being a supporter. I just keep it fair.

No, I do not feel this is minor, especially the filters marketed for the dirtiest of off road machines like dirt bikes and ATVs. Their small valves are very sensitive to dirt contamination and can lead to a very early valve job being needed.
 
Understood and good points all around. Plenty of dyno tests in the MK7 VW world that show that when combined with other modifications to the stock air box etc. that there are gains from using high-flow filters. You are also correct that favorable conditions are a big part of this but to the "OH MY GOD K&N WILL RUIN YOUR VEHICLE" crowd, that needs to be taken into account. If I lived out in the desert would I use one? Maybe not. I do have to laugh at the mpg comment because yeah...that's laughable. It flows more air at the expense of filtering period.
 
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I have a 2009 Cobalt SS Turbo with the LNF 2.0 (260 hp stock, K04 stock turbo). I ran the K&N hot air intake for years and had it tuned right. I decided to go back to the stock airbox, and immediately felt the car had much better performance. The K&N allowed the intake air temps to rise well over 100F which is not good for power. The stock airbox kept the temperatures much more consistent to ambient. I've run stock airboxes on all my vehicles since then, and have datalogged evidence to show those K&Ns yield zero gains for performance even with the twin-turbo EcoBoost engines.
 
There's a time and a place for K&N but IMO on stock, daily driven cars it's not the ideal choice. An ex-friend had a K&N CAI on his truck and he neglected it badly - it was never cleaned and it wasn't installed right. I had his intake apart and I saw a gaping hole on the fender side of the filter where it was rubbing against a mounting bolt. MAF was coated in oil.

I cleaned it up for him but I said to find the stock intake setup. He got one off eBay and I installed it. Truck seems to run a little better and it's not as loud as it was with the K&N.

Now, if it was a car that sees the track, a race car/bike or something that needs more air flow I can see a K&N being appropriate. They're popular for boats.
 
K&N would do poorly in my area due to the dusty conditions of the farm i would prefer a pleated filter or oil bath air cleaner over a pre oiled rock catcher.
 
Originally Posted by metroplex
I have a 2009 Cobalt SS Turbo with the LNF 2.0 (260 hp stock, K04 stock turbo). I ran the K&N hot air intake for years and had it tuned right. I decided to go back to the stock airbox, and immediately felt the car had much better performance. The K&N allowed the intake air temps to rise well over 100F which is not good for power. The stock airbox kept the temperatures much more consistent to ambient. I've run stock airboxes on all my vehicles since then, and have datalogged evidence to show those K&Ns yield zero gains for performance even with the twin-turbo EcoBoost engines.


True & agree. Wonder if washing the stock air filter , drying in natural air and reusing couple of times would lead to a much higher dirt ingress probability compared to a brand new stock air filter element ?
BTW would washing result in any changes in airflow properties of the stock element air filters ?
 
Originally Posted by rooflessVW
Originally Posted by oldhp
Now you are getting true "colder" air than with the open, inside the hot engine compartment. A stock engine doesn't need anything better than the stock air box / air filter from the factory.

I've said it before and I'll say it again - stock components are always a compromise and are developed to find the balance between performance and efficiency while also considering noise and ease of serviceability.

It is entirely feasible to shift the balance toward your preferences with aftermarket parts. Just based on the size of the factory resonator, the K&N should give the engine some nice intake noise, at a minimum.

Something else not many take into consideration - that mass of black plastic certainly retains a lot of heat - and is sitting in the engine bay the same as the K&N.


All good points but that metal K&N intake tube takes on more heat (and retains it) than the stock plastic assembly.
 
Originally Posted by GMBoy
Originally Posted by rooflessVW
Originally Posted by oldhp
Now you are getting true "colder" air than with the open, inside the hot engine compartment. A stock engine doesn't need anything better than the stock air box / air filter from the factory.

I've said it before and I'll say it again - stock components are always a compromise and are developed to find the balance between performance and efficiency while also considering noise and ease of serviceability.

It is entirely feasible to shift the balance toward your preferences with aftermarket parts. Just based on the size of the factory resonator, the K&N should give the engine some nice intake noise, at a minimum.

Something else not many take into consideration - that mass of black plastic certainly retains a lot of heat - and is sitting in the engine bay the same as the K&N.


All good points but that metal K&N intake tube takes on more heat (and retains it) than the stock plastic assembly.

It may. Plastic holds a ton of heat as well.

Which one has better heat transfer once heat soaked? Which one cools faster?
 
Originally Posted by circuitsmith
According to this source steel is roughly 100X as heat conductive as plastic.

It's thin wall aluminum.

I'd agree that thick steel tubing is a poor choice of intake material.
 
Originally Posted by rooflessVW
Originally Posted by GMBoy
Originally Posted by rooflessVW
Originally Posted by oldhp
Now you are getting true "colder" air than with the open, inside the hot engine compartment. A stock engine doesn't need anything better than the stock air box / air filter from the factory.

I've said it before and I'll say it again - stock components are always a compromise and are developed to find the balance between performance and efficiency while also considering noise and ease of serviceability.

It is entirely feasible to shift the balance toward your preferences with aftermarket parts. Just based on the size of the factory resonator, the K&N should give the engine some nice intake noise, at a minimum.

Something else not many take into consideration - that mass of black plastic certainly retains a lot of heat - and is sitting in the engine bay the same as the K&N.


All good points but that metal K&N intake tube takes on more heat (and retains it) than the stock plastic assembly.

It may. Plastic holds a ton of heat as well.

Which one has better heat transfer once heat soaked? Which one cools faster?



I don't know for sure but I guess when it's all said and done they each get to the heat saturation point but just at different times.
 
If two intake tubes of the same wall thickness are compared, the metal tube will conduct more engine bay heat into the air stream going to the engine. Ideally, the intake tube should be as thermally insulated as possible.
 
Originally Posted by rooflessVW
Originally Posted by circuitsmith
According to this source steel is roughly 100X as heat conductive as plastic.

It's thin wall aluminum.

I'd agree that thick steel tubing is a poor choice of intake material.

So I could have said aluminum is roughly 400X as heat conductive as plastic.
 
Originally Posted by circuitsmith
Originally Posted by rooflessVW
Originally Posted by circuitsmith
According to this source steel is roughly 100X as heat conductive as plastic.

It's thin wall aluminum.

I'd agree that thick steel tubing is a poor choice of intake material.

So I could have said aluminum is roughly 400X as heat conductive as plastic.

It heats faster, yes. It also cools much much faster than plastic, especially when there is 10 times more of it.
 
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