[HP Autosport]

Curious to know what a few different type of filters would flow vs no filter at all? Here are the results measured in percent of flow...

Flow bench set-up to suck through at 22 inches of vacuum, ambient temp was a cool 70F..

BMW Intake Box with stock, clean air filter....90%...Remember, this is a clean paper filter, put a few miles on it, the percent flow will drop drastically

BMW Intake Box with new/clean AFE Pro-Dry filter...90%...To our surprice there is no flow gain with the AFE filter at all

BMW Intake Box with HPA used/~1500 miles high-flow foam filter...90.5%...The result isn't as impressive as we thought it would be, but it does flow better the previous two filters tested, even with 1500 miles already on it. We are not surprised this additional air flow translated to 4-5 hp and 4-5 ft/lb at the wheels on a dyno recently done by "FrankiE90"

http://www.e90post.com/forums/showthread.php?t=416803

You ready to see the flow percent with no filter at all?

BMW Intake Box with no air filter at all.... 92%...It's far from 100%, there is restriction with the oem box for sure and leaves room for improvement.


Why foam? Because,
compared to paper or other filter technologies, "Open Cell" Polyurethane foam achieves optimum performance
against three key criteria:


Maximum Air Flow - the
ability to allow air to pass through without causing a
large drop in pressure.

Cleaning Efficiency - the capability to arrest a high proportion of airborne dust while feeding the engine
clean air.

Dust Load-up Tolerance -
the capability to absorb a
large amount of dust without reducing air flow capacity.

[BMW-NC]

So, no need to purchase an aftermarket filter. Those .5% are in my eyes as effective as not having lunch before getting in the car.
Just my .02...

[HP Autosport]

Originally Posted by BMW-NC

So, no need to purchase an aftermarket filter. Those .5% are in my eyes as effective as not having lunch before getting in the car.
Just my .02...

Although the diff. is low, the 0.5% is worth 4-5 hp and tq at the wheels. The oem paper element quickly loads up with dust, unless you plan to keep changing your paper element every 3-5K miles or sooner to retain the same flow.

By the 3rd time you replace your paper element, you could have bought a higher flow foam or another media, just clean it(oil if needed) and reinstall when it's dirty.

[enrita]

Can you get a version of the foam filters that fits the injen intake?

[marconi118]

any test for the N54?
even without filter it should be below 100% it seems more restrictive than the N55 one...

[mwahlert]

we are talking about 5whp.... seriously?

[jaguar36]

I'd like to see some test data on a dirty air filter.

[HP Autosport]

Originally Posted by mwahlert

we are talking about 5whp.... seriously?

Have a look at the Dyno results.

[MisterSkiMask]

Originally Posted by mwahlert

we are talking about 5whp.... seriously?

You spoiled greedy bastard!

[subieworx]

Should do another test with a stock filter that has 15k miles on it and see how it flows.

[vasillalov]

Originally Posted by HP Autowerks

BMW Intake Box with new/clean AFE Pro-Dry filter...90%... To our surprice there is no flow gain with the AFE filter at all

Really? AFE filters have been long denounced in VW/AUDI scene as power robbers and having really crappy filtration properties. There was an extensive test performed on over 20 different brands of drop-in air filters. This test was done by a VWVortex member who happened to be a mechanical engineer.

I've been preaching this ever since I joined this forum... Only now it is beginning to trickle down...?

On the side note: you should do a test on all of the oiled filters and you will be absolutely astonished how badly most of these filters do!

[MisterSkiMask]

Originally Posted by vasillalov

Really? AFE filters have been long denounced in VW/AUDI scene as power robbers and having really crappy filtration properties. There was an extensive test performed on over 20 different brands of drop-in air filters. This test was done by a VWVortex member who happened to be a mechanical engineer.

I've been preaching this ever since I joined this forum... Only now it is beginning to trickle down...?

On the side note: you should do a test on all of the oiled filters and you will be absolutely astonished how badly most of these filters do!

Indeed they shoud spend hundreds of hours so you can beat off...

[vasillalov]

Originally Posted by MisterSkiMask

Indeed they shoud spend hundreds of hours so you can beat off...

[techlogik]

Originally Posted by mwahlert

we are talking about 5whp.... seriously?

According to the dyno, it appears 3.4whp and 3tq.

[mwahlert]

Originally Posted by techlogik

According to the dyno, it appears 3.4whp and 3tq.

yeh - heh - i meant it sarcastically... is anyone really going to get excited about < 5whp ? you can't feel that...

[bigdaddycane]

I bought an ITG panel filter from HPS for the N54 airbox and it definitely feels better than the stock filter. I have dealt with many different intakes on my previous cars and am not falling victim to the "placebo affect". The stock panel filter is so restrictive that almost any after market filter is going to flow better.

The reason I went with a panel filter (for now) is due to not liking the designs of the dual cone filters currently on the market. Almost all of them are suseptible to heak soak, not matter what that ONE posted test shows. Sit in stop and go traffic and your DCI intake is sucking nothing but hot air due to zero shielding.

[jaguar36]

Those graphs are quite interesting. It doesn't seem to be a consistent 5hp gain at all only between 5.5k and 6k RPM. Its also a very small gain compared to the noise on the chart, some other variable such as engine temp or something else might have also caused the gain. If you look at 5.5k to 6k band, it runs exactly in time order, that is each successive run has more HP than the one before it.

Regardless 5HP isn't really enough to matter.

The better/worse filtration of the foam filter could have significantly more long term effects.

[bigdaddycane]

guys, don't sleep on the torque gains....

[dzenno]

This is an excellent post that shows there's as much gains with an aftermarket filter inside the stock airbox as some of us originally thought..~5whp...also shows that the stock intake design is good at "stock-like" power levels...

[Professor///M]

My question is though, why haven't automakers adopted these as standards, and continuously go back to paper filters?

Is it just a cost thing?

What's the difference between that and a K&N filter?

[bigdaddycane]

My question is though, why haven't automakers adopted these as standards, and continuously go back to paper filters?

DOT Federal Law

[vasillalov]

Originally Posted by bigdaddycane

DOT Federal Law

Umm, they put the exact same filters everywhere else in the world, yet the emissions standards are completely different from place to place. So that's highly unlikely.

Quality paper filters actually perform well and work CONSISTENTLY in all kinds of conditions. Ever wondered what happens to an oil filter when driven in extreme heat or extreme cold? The efficiency of the such filters changes in different conditions. Also, paper filters are perfectly sufficient for OEM applications and stock power levels.