Air filter

[MikeM.]

ok so i may have put my foot in my mouth that time...

but what i meant was the extra/deeper pleats in a OE paper filter don't make the air flow better(vs the K&N) they help collect dirt(for longer service life of the paper filter)

There is no way to tell which filter has less resistance without testing the specific filters in question (the CX-5 OEM filter with it's larger surface area or the K&N that has a coarser filter media). But I can tell you this - the OEM filter causes very little pressure drop, so little that even the most free flowing filter will not measurably increase performance.

For proof of this simply do two back to back 0-60 (or zero to 100) runs - one with the OEM filter installed and one with it removed entirely. Or use a dyno. There will be no difference in performance. That's how good the OEM filter is.

The OEM filter is not actually made of paper - it's a synthetic fiber mat that is over 1mm thick and flows more freely than any paper media I've seen. It is less affected by humidity and moisture than a traditional paper filter as well. The airbox is designed to allow larger particles to fall back out of the filter media via gravity in order to increase it's service life. An oiled filter is sticky so that benefit is lost. Also, the OEM filter has a massive surface area of 378 Sq. inches or 2.6 square feet. And contrary to your repeated assertions, more surface area does flow more freely than less surface area. And these facts explain why more power CAN NOT BE REALIZED BY REPLACING THE AIR FILTER (or even removing it altogether). The air filter in the CX-5 is not restrictive enough to reduce the volume of air the engine can pass.

However, the links you provided were very enlightening in terms of just how many grams of abrasive dirt a K&N filter allows to pass directly into the nice clean and well lubricated engine. After reading the results of those tests, I don't think any self-respecting auto enthusiast could use an oiled K&N filter in any engine that was worth treating well. Thank you for illustrating the reason why a growing body of auto enthusiasts will not run K&N filters in their vehicles. The facts are finally getting out there.

 

[Bladecutter]

http://cars.about.com/od/productreviews/fr/ag_knfilter.htm

http://www.nicoclub.com/archives/kn-vs-oem-filter.html

http://www.knfilters.com/faq.htm

if you read the info and see the graphs on the 2nd link they directly show that the k&n filter has superior flowing ablity compared to the multiple OEM and OEM style filters...yes if can allow more small particles of dust and dirt through compared to the OEM or OEM style

You didn't actually read anything on that second link, did you.
Here, let me quote part of it for you:

The AC Delco filter test ran for 60 minutes before exceeding the restriction limit while the AMSOIL and K&N tests each ran for 20 and 24 minutes respectively before reaching max restriction.

In 60 minutes the AC Filter accumulated 574gms of dirt and passed only 0.4gms. After only 24 minutes the K&N had accumulated 221gms of dirt but passed 7.0gms.

Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. See the data tables for a complete summary of these comparisons.

And if you looked at ANY of the graphs, the K&N filter came in last, or next to last on just about every one.

That link didn't help you point at all, and destroyed your whole argument, honestly.
You should READ that whole link, before you try to use it to help prove your point (which you can't).

BC.

 

[apexanimal]

The best way to access any performance gain is to take a pressure drop measurement with different filters...

Using one of these: http://www.coleparmer.com/buy/product/95358-dwyer-magnehelic-differential-pressure-gauge-2030-0-30-inh2o.html

I have a 0-3" gauge for aero testing, but you need a much higher one for intake testing...

 

[MikeM.]

I have a 0-3" gauge for aero testing, but you need a much higher one for intake testing...

In order to test for the amount of air filter restriction, the vacuum gauge would be placed between the throttle plate and the air filter. The pressure in this area of a CX-5 will be very close to ambient pressure - it is not necessary to have a gauge with a wide range. Test should be conducted on the road with the throttle wide open and at peak hp RPM's (5700 RPM's on 2.5L and 6000 RPM's on 2.0L). Then remove the air filter (or switch to K&N) and perform the same test. The readings will be so close to equal they will be indiscernible for all practical purposes (proving the OEM air filter is free flowing). Both filters should be clean. This is especially important for the K&N because, according to the test data provided by nekkidlad, the K&N "plugs up" much easier (even while passing more dirt into the engine).

 

[apexanimal]

A vac gauge would be okay, but won't be as sensitive as the magnehelic... And you would want to get the 0-30 as I'm not sure if the 0-20 would be enough...

Ill just leave these here... This is how I've made adjustment to my intakes for several years now:

http://www.autospeed.com/A_107824/cms/article.html
http://www.autospeed.com/cms/A_112210/article.html?popularArticle
http://www.autospeed.com/cms/article.html?&A=112734
http://www.autospeed.com/cms/article.html?&A=1023
http://www.autospeed.com/cms/A_111109/article.html
http://www.autospeed.com/cms/article.html?&A=0646

 

[MikeM.]

Ill just leave these here...

http://www.autospeed.com/A_107824/cms/article.html
http://www.autospeed.com/cms/A_112210/article.html?popularArticle
http://www.autospeed.com/cms/article.html?&A=112734
http://www.autospeed.com/cms/article.html?&A=1023
http://www.autospeed.com/cms/A_111109/article.html
http://www.autospeed.com/cms/article.html?&A=0646

Thanks for those. The relevant portion would be:

I have never seen a standard filter element cause any more than a tiny proportion of the total restriction in the intake of any standard car! In fact, the pressure drop across the filter is usually in the range of just 1-2 inches of water.

And I'll tell you the CX-5 will be at the low end of this range. That's how free-flowing the OEM filter is.

 

[xtrailman]

I fitted a K&N filter to a Mk1 Cortina, when I didn't know better, it gave me no performance or MPG increase, but it looked good and made a sporty noise, it was also cheaper in those days to just remove it and clean it out, re-oil and replace, but it was obvious that it was going to let a lot more dirt into the engine.

I no longer fit any gadgets, and never use any additives, always use supermarket fuel, and have never had a problem.

 

[MikeM.]

I fitted a K&N filter to a Mk1 Cortina, when I didn't know better, it gave me no performance or MPG increase, but it looked good and made a sporty noise, it was also cheaper in those days to just remove it and clean it out, re-oil and replace, but it was obvious that it was going to let a lot more dirt into the engine.

I know what you mean. Assuming I keep the CX-5 until it has 120,000 miles on the clock, I only need to buy 3 air filters. With the K&N I have to buy one (very expensive) filter (I'm being generous here calling it a filter) - plus a filter oiling kit. Then, every 5-10,000 miles I need to remove it, wash it, rinse it, let it dry, oil it and re-install it. I would be willing to do this if there was some benefit, but there's not.

 

[apexanimal]

Thanks for those. The relevant portion would be:

I have never seen a standard filter element cause any more than a tiny proportion of the total restriction in the intake of any standard car! In fact, the pressure drop across the filter is usually in the range of just 1-2 inches of water.

And I'll tell you the CX-5 will be at the low end of this range. That's how free-flowing the OEM filter is.

We don't really know where on the range it would be until tested...

I would hope it would be on the better end, but the restrictions that it has and how to improve it would only come from the magnehelic...

 

[MikeM.]

We don't really know where on the range it would be until tested...

I would hope it would be on the better end, but the restrictions that it has and how to improve it would only come from the magnehelic...

It sounds like you are expanding the discussion to include potential intake tract restriction. This discussion has been about the potential performance benefit (or more accurately, the lack thereof) of replacing the OEM filter media with a K&N cotton gauze element.

And if you need to compare the filter restriction with instruments, be my guest (and post the results right here). But I promise you won't be able to improve it by dropping a K&N in there.

 

[apexanimal]

I'm sure you could drop the restriction by a couple of inches by switching filters... But the question is would you want to and would it be "worth it?" Personally, probably not, but in all independent testing the k&n do flow better (with known trade-offs as we've noted)...

I'm very aware of what the original topic is... Threads tend to move on from the op and evolve as they go... So it is with this one.

 

[V8toilet]

It is highly unlikely that there is a replacement filter out there that will out perform the stock Mazda filter without compromising filtering performance itself. I did some back to back Dyno testing on a Toyota Tundra V8 with a stock filter against a K&N drop in filter and lost 4 RWHP with the k&N filter. We wanted to find out why so we took them apart and found out that the stock filter had 50% more surface area than the K&N did (stock had more pleats). Even though the K&N filter flowed more than the stock filter per a square inch the stock filter overall flowed better because there was less pressure drop across the filter due to the larger surface area of the stock filter. Even trying to improve on the filter boxes themselves is hard to do without compromising low end torque in leu of top end horsepower. In my opinion the Skyactive family of engines are so highly tuned that they're isn't any room for improvement with bolt on parts short of big ticket items like forced induction. The stock Mazda filter looks exactly like a Toyota filter to the point that they look like they came from the same factory.

There are no free lunches, something has to be compromised.

 

[apexanimal]

Completely agree that if it flows more, it'll likely be letting more dirt in...

I still don't buy that there's nothing that can be done to make better than it is currently... Intakes will have restrictions due to packaging restrictions, cost, and nvh concerns... Exhaust will have restrictions due to the same (although the header design on these is really awesome)...

On a n/a engine all of these restrictions and improvements will be relatively small and incremental (esp with no internal or head work)... And quite a bit of money/testing can go into only getting another 5hp or so... But it can be safely had if people want to go for it... A retune for 93oct would probably be the best bang for the buck...

 

[apexanimal]

I'm "talking" a lot... Ill yield the floor to everyone else