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Best turbo air filter

I ripped out my stock airbox so I could modify it and do some cool things with the paper filter.


But then I started rummaging around my dads garage and found an old cone filter that is made out of the same material a paper filter is made out of. It was on his 87 G.N. T type.


So I made a custom little stand so the filter would sit right where the old air box was and it was the most amazing increase I have ever felt in just swapping out an intake.


I think everyone should find one of those.
 
For anything short of a full race N/A motor, you really need some decent filter material in place, especially in a dry/ dusty environment where you are more likely to get fine airborne particles.

If you think of it as travelling on a road where other vehicles as well as your own have just disturbed and dispersed any dust lying on the surface into the air, and having a large air pump under your hood trying its best to suck it all in, that much is obvious.

Many aftermarket 'peformance' filters have dubious performance at either filtering OR flowing air, and are unable to prevent the finest particles being ingested by the engine. This can lead to accelerated wear of the engine internals and the compressor wheel, even if there is any kind of power gain.

Sometimes it isn't the stock filter or airbox capacity that is the problem but baffling built in to reduce air noise, and the aftermarket filter only works by sidestepping this. The best way to check for intake restriction must be checking through the intake for pressure drop with a manometer. (which will also show the truth about the filter as well)


Ripping out the stock airbox, filter and ducting and replacing with a cheap foam filter that then draws hot underbonnet air on a +T engine......good idea?..:lol:

If you haven't already guessed I'm not a great fan of foam type filters for several reasons.

If there is any question of the stock filter being restrictive on a high output motor, one option that hasn't been mentioned is the use of two stock paper elements. This can also be arranged in any way to fit available space, retains excellent filtering properties while doubling airflow potential, and is much cheaper than most of the aftermarket options.

As my new +T engine is having to draw intake air from a slot in the front of the car only about 8" above the road surface I'm making an aluminium airbox to carry two stock Fram panel elements from the VW Golf GTI who's dimensions just happen to fit the available space nicely. For the sake of a lttle DIY sheetmetal fabrication it is possible to have the best of both worlds.
 
I ripped out my stock airbox so I could modify it and do some cool things with the paper filter.


But then I started rummaging around my dads garage and found an old cone filter that is made out of the same material a paper filter is made out of. It was on his 87 G.N. T type.


So I made a custom little stand so the filter would sit right where the old air box was and it was the most amazing increase I have ever felt in just swapping out an intake.


I think everyone should find one of those.

You really need to have measureable improvements or gains.

I'm not trying to be critical here, but honestly changes in the noise levels just like with exhaust system mods can be very deceiving. Its too easy to make something sound or feel faster or more pokey!

Tweeks to the airbox and improved cold air ducting to it would more likely have been time better spent.
 
i live on a half mile dusty ass dirt road. been running k&n's for years, and you would eat your words if you saw how much dirt/dust comes out when i clean the ****ers

me too i had one. you'd eat your words if you saw how much dirt i scraped out of my intake manifold!!!

ever do a leakdown test? 8% leakdown means your loosing 24% of your power.
 
me too i had one. you'd eat your words if you saw how much dirt i scraped out of my intake manifold!!!

ever do a leakdown test? 8% leakdown means your loosing 24% of your power.

more proof K&N sucks. I dont understand why so many of you blindly believe in K&N just because people have been dropping their name for as long as you can remember
 
So leaving out k&n if you want to ditch the factory air box, what kind of filter would filter best? I don't think the filter in the 7 is the issue, I think it is the air box its self. (that small sharp 90? can't be great and the inlet on the box isn't exactly large)
 
There are other things that cause leak down besides your brand of air filter.


And I have a feeling some of the people obsessing over air filters and how the wrong one can seriously harm an engine (lol) might also be the same type of people to abuse their engines in other ways (driving like a goon, redlining often, etc etc), so it probably evens out in the end. :roll:
 
Stock Mann paper, end of story, use unless your out to remove the air box for plumbing or change of turbo issues, nothing filters as well as paper, and it flows just fine for any HP level.

1000x

The stock airbox and MANN filter provide a cooler, and MUCH better filtering system than the cone filters everybody likes to install. Especially if you make a good cold air duct for it.

And I have a feeling some of the people obsessing over air filters and how the wrong one can seriously harm an engine (lol) might also be the same type of people to abuse their engines in other ways (driving like a goon, redlining often, etc etc), so it probably evens out in the end. :roll:

I've gotta disagree. The dirt and debris that pass directly through a K&N filter will drastically increase wear on the turbo and the cylinder walls. I've seen red blocks lose compression and have chewed up compressor wheels with just one year of running a K&N in dusty/dirty environments. Red blocks with paper filters and good oil maintain the factory crosshatch on the cylinder bores, and perfect compression almost indefinitely- even if ran really hard.

Running a K&N is (literally) pouring sand into your intake with the motor running. There's an experiment I saw where a guy ran a piece of tape behind his K&N and found large sand particles stuck to it- whereas there was no debris with a stock paper filter.
 
If I had a race car- I'd probably run no filter on the track, and stock filter on the street rather than mess with K&N crap which filters about like no filter, and flows only a little better than stock.
 
FWIW while I personally think that a K&N isn't something I'd want on my car (I don't want any filter i can see light through :lol:) the car i parted had a K&N on it, probably for 100k or more, and with 433k on the original engine it still had crosshatching in the bores. My car had one when I got it, I replaced it with a mann almost right away, when I pull the head off we'll know how that looks, but i am expecting to see cross hatching.

My reasoning for wanting to get rid of the stock box has to do more then anything with the fact that the clips always seem to break off the stock boxes when they get to about 20 years old meaning that finding a good box is getting hard (at least from the cars i've looked at) and many only have 2 or 3 of like 5 clips on them which makes me doubt how good the filter is sealing in the box. I'd like to be able to ditch the box mainly for that reason (I have a heat shield to go in its place).
 
K+N cotton filters have actually proven to be very effective on race engines where filtration is more often of secondary importance. The problem is that the vast majority of these filters sold end up on road cars where this is not the case. You can't really blame K+N for selling there kit where people ask for it, even where it is less than suitable.

Some 'other' makes and types of filter lack even the K+N's good points, with all of the disadvantages and sometimes some other nasty ones as well.


For 95% of the time the paper element is the way to go.
 
So leaving out k&n if you want to ditch the factory air box, what kind of filter would filter best? I don't think the filter in the 7 is the issue, I think it is the air box its self. (that small sharp 90? can't be great and the inlet on the box isn't exactly large)

I wish they made paper cone filters :(

I just ordered a Fujita universal filter (known to filter very well.) I'll let you all know if it looks like it will filter well when it arrives.
 
How do you guys mount your cones/pods (by mount I mean the pipe used and securing) and what do you do with the CBV sucking in unfiltered/unmetered air?
 
1000x

The stock airbox and MANN filter provide a cooler, and MUCH better filtering system than the cone filters everybody likes to install. Especially if you make a good cold air duct for it.



I've gotta disagree. The dirt and debris that pass directly through a K&N filter will drastically increase wear on the turbo and the cylinder walls. I've seen red blocks lose compression and have chewed up compressor wheels with just one year of running a K&N in dusty/dirty environments. Red blocks with paper filters and good oil maintain the factory crosshatch on the cylinder bores, and perfect compression almost indefinitely- even if ran really hard.

Running a K&N is (literally) pouring sand into your intake with the motor running. There's an experiment I saw where a guy ran a piece of tape behind his K&N and found large sand particles stuck to it- whereas there was no debris with a stock paper filter.

You missed my point entirely...the point I made had nothing to do with how poorly a filter flows. It was a reflection on the way many TB'ers I know personally treat their cars. There are other variables besides choice of air filter than can potentially damage a car!

But, I too have to disagree. EVERY car I have EVEN owned has run a K&N...since I was 16 years old and started "tuning" an '86 VW GTI. lol. And, EVERY engine I've EVER had the head off of, still had the factory cross hatch marks in the bores, still had perfect compression at high high mileage (unless I had melted a piston from too much boost), and otherwise ran flawlessly. Several of the cars I drive the hardest with K&N's had over 200,000 miles on them (3 Volvos and 4 VW's I drove hard/raced and modified were past the 200k mark). Almost all of them were daily drivers. My 944 Spec race car saw street and very aggressive track driving, and had 189k miles on the engine. I knew the previous owner, and it had a K&N for most of its life.

Now...couple that real world observation with this: simply removing the lower half of my airbox and creating a ram-air setup on my 850 recently gained a consistent 2.2mph in trap speed (it already had a K&N with the stock airbox and factory cool air ducting on the previous runs).

If such a seemingly tiny modification netted such a drastic improvement in trap speed (from 96.0 to 98.2mph), that suggests trying to tune an engine for performance while using a paper air filter would be like trying to go snorkeling while breathing through a coffee stir straw. It's extraordinarily counter productive.

An engine is a giant air pump. The more air you move, the more power it makes. A paper air filter is extremely restrictive. Certainly, more flow is going to mean less filtration. But to claim it's the same as "pouring sand into an engine" simply contradicts all of the millions of tuned cars out there using K&N's and running great, living long lives. I especially think of the amateur Baja racers, in about the sandiest, dirtiest conditions anywhere, using a K&N with a Pre-Filter. The amateur guys don't rebuild engines after each race...hardly. They run an engine for quite a while. And many (most) of them still choose K&N.

Not trying to sound like a K&N fan boy, because I'm not...I'm just saying, there's some exaggeration going on here!
 
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