Filtration properties of aftermarket filters
Discussion
So, aftermarket performance airfilters. Whether or not they actually give you more power is another matter, but are they any good at actually filtering the air?
I have searched high and low and can only find one example of where someone has tested how good they are, and the results were scary! I think K+N came off particularly poorly, yet their products are used the world over.
Than again, am I just being over-cautious? Would the reduction in filtration be too small to have any effect?
I have searched high and low and can only find one example of where someone has tested how good they are, and the results were scary! I think K+N came off particularly poorly, yet their products are used the world over.
Than again, am I just being over-cautious? Would the reduction in filtration be too small to have any effect?
Defcon5 said:
So, aftermarket performance airfilters. Whether or not they actually give you more power is another matter, but are they any good at actually filtering the air?
I have searched high and low and can only find one example of where someone has tested how good they are, and the results were scary! I think K+N came off particularly poorly, yet their products are used the world over.
Than again, am I just being over-cautious? Would the reduction in filtration be too small to have any effect?
Unfortunately its hard to believe most of the tests, as usually they are sponsored results.I have searched high and low and can only find one example of where someone has tested how good they are, and the results were scary! I think K+N came off particularly poorly, yet their products are used the world over.
Than again, am I just being over-cautious? Would the reduction in filtration be too small to have any effect?
It may be many years old...but Mr Vizard tested plenty with his A-Series testing, and generally K&N performed very well.
The fact that they are used in competition the world over, including many off road racers....must mean something.
But I think most paper type elements will always filter better. Although they will also clog up much faster.
stevieturbo said:
The fact that they are used in competition the world over, including many off road racers....must mean something.
Possibly that they'll give you good filtration without reducing airflow for a short period of time before needing to be thrown away?Possibly that a lot of them get sponsorship from these companies - sometimes as part of the competition organiser's sponsorship/publicity package?
mmm-five said:
stevieturbo said:
The fact that they are used in competition the world over, including many off road racers....must mean something.
Possibly that they'll give you good filtration without reducing airflow for a short period of time before needing to be thrown away?Marf said:
mmm-five said:
stevieturbo said:
The fact that they are used in competition the world over, including many off road racers....must mean something.
Possibly that they'll give you good filtration without reducing airflow for a short period of time before needing to be thrown away?Personally I like to replace my £5 air filter while I'm waiting for my oil to drain during an oil service, rather than paying £80 for a filter that I'm going to have to clean & re-oil.
mmm-five said:
Marf said:
mmm-five said:
stevieturbo said:
The fact that they are used in competition the world over, including many off road racers....must mean something.
Possibly that they'll give you good filtration without reducing airflow for a short period of time before needing to be thrown away?Personally I like to replace my £5 air filter while I'm waiting for my oil to drain during an oil service, rather than paying £80 for a filter that I'm going to have to clean & re-oil.
On my last car (306 HDi) someone did a test with about 10 filters on the dyno, all about 148-151bhp in total, with the highest one being with no filter at all.
There really is NO point on a modern car. Think old carbs with a pancake filter and a 1" inlet to a huge K&N filter, nice.
Modern car with ram-air intake setup and cold-air intake all in one, setup very efficiently, not so nice.
Also, from experience, I've always found particles post filter, suspended in oil on the clean side of the filter housings, with both K&N and Pipercross foam types.
K&N are great for rallying or heavy duty off-road etc, because they can be cleaned, but what road car needs that feature? The worst I get are a few leaves and flies, not a few hundred grams of sand and mud or something...
Best with paper for being clean (most people with K&N etc never clean them, they look black, and likely do sod all for power or filtration) as you change it often, and for good filtration, and if it's half-modern, good performance too!
Used to be a worthwhile mod on most cars, today, increasingly less I think.
Dave
There really is NO point on a modern car. Think old carbs with a pancake filter and a 1" inlet to a huge K&N filter, nice.
Modern car with ram-air intake setup and cold-air intake all in one, setup very efficiently, not so nice.
Also, from experience, I've always found particles post filter, suspended in oil on the clean side of the filter housings, with both K&N and Pipercross foam types.
K&N are great for rallying or heavy duty off-road etc, because they can be cleaned, but what road car needs that feature? The worst I get are a few leaves and flies, not a few hundred grams of sand and mud or something...
Best with paper for being clean (most people with K&N etc never clean them, they look black, and likely do sod all for power or filtration) as you change it often, and for good filtration, and if it's half-modern, good performance too!
Used to be a worthwhile mod on most cars, today, increasingly less I think.
Dave
350Matt said:
Yes but then you don't get the power gain from the removing the std / cheap filter restriction do you.
If it was giving you 1-2bhp on a 1-2bhp motor, then you'd easily be able to tell the difference, but anyone who can feel a 1-2bhp increase on a car with more than 50bhp should sell their arses to Mustang, DynoDynamics, Dynajet, Dynapack, etc. as it's obviously more accurate than any of their equipment 
The oiled filters do work better, initially. But if their cleaning properties are so great, then their elements will catch more crap in the first 1,000 miles than the original one will in 10,000 miles. This means that the oiled filter will be performing WORSE after 1,000 miles than the original one - although you could always stop by the side of the road and clean & re-oil it every 1,000 miles to keep your 1-2bhp that you've paid £80 for.
K&N on modern stuff is snake oil, just like all those additives and things for oil that are clearly, expressly prohibited if you want to keep your warranty intact, and like most of those common rail diesel cleaning additives, despite the Bosch manuals saying DO NOT USE THEM etc.
It seems people like snake oil
It seems people like snake oil
mmm-five said:
350Matt said:
Yes but then you don't get the power gain from the removing the std / cheap filter restriction do you.
If it was giving you 1-2bhp on a 1-2bhp motor, then you'd easily be able to tell the difference, but anyone who can feel a 1-2bhp increase on a car with more than 50bhp should sell their arses to Mustang, DynoDynamics, Dynajet, Dynapack, etc. as it's obviously more accurate than any of their equipment The oiled filters do work better, initially. But if their cleaning properties are so great, then their elements will catch more crap in the first 1,000 miles than the original one will in 10,000 miles. This means that the oiled filter will be performing WORSE after 1,000 miles than the original one - although you could always stop by the side of the road and clean & re-oil it every 1,000 miles to keep your 1-2bhp that you've paid £80 for.
Paper elements clog up fast, and become very restrictive. But if the paper element is adequate for the airflow levels the engine will consume, then ultimately it is the best choice.
And not too many of drive in such harsh environments, that filter cleanliness over low milages is of any real concern.
If I could buy a cheap, disposable filter that would meet my airflow requirements, and fit in the sapce provided, I would of course use one.
But I just dont think that's likely. I was using K&N before, but now using a Green filter....mostly as it was slightly cheaper...and for colour matching purposes lol.
I doubt my car will need to do 100k before a rebuild, and I doubt I'll ever drive anywhere so harch, that the air needs to be throughly cleaned.
All you need to do is choose the right filter, to suit your needs. There is no best.
You can still tap out a paper filter fairly easily every 1000 miles, much easier than a full on filter clean with a long life one
I may well test a few filters on my NA car now, and maybe on a damp day, with none at all (just for a single acceleration run) and do some comparisons. I doubt there is much in it to be honest. If paper really were costing so much power/efficiency they would have been superseded by now in the quest for easy power/economy benefits so much sought after these days.
If you have an older car, I see no problem with K&N etc, but newer ones are so damn good out of the box!
Dave
I may well test a few filters on my NA car now, and maybe on a damp day, with none at all (just for a single acceleration run) and do some comparisons. I doubt there is much in it to be honest. If paper really were costing so much power/efficiency they would have been superseded by now in the quest for easy power/economy benefits so much sought after these days.
If you have an older car, I see no problem with K&N etc, but newer ones are so damn good out of the box!
Dave
Hang on a mo
The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
350Matt said:
Hang on a mo
The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
Not really, it's because the filtration is horrendous. The micron filtration level for almost any gauze / foam filter is a LOT worse than a paper type element. The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
Also, an air filters' restriction depends on both its filtration level (i.e. how big the holes are), AND the surface area. Look at a paper air filter, and how much surface area there is - there are a LOT more pleats. Generall, a paper filter will have at least 3x as much surface area as a cotton gauze filter, usually a lot more.
I actually tested the restriction on my MR2 Turbo - it came with an Apexi induction kit. I replaced it with a standard airbox, and paper element. The restriction was lower with the standard intake system. The standard system also got much lower intake temperatures, as it was ducted to the side inlet.
Otto said:
350Matt said:
Hang on a mo
The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
Not really, it's because the filtration is horrendous. The micron filtration level for almost any gauze / foam filter is a LOT worse than a paper type element. The reason the cotton gauze filters ( K& N et al) haven't been adopted by the major manufacturers is cost if its even 1 dollar cheaper they'll fit a paper item.
After all sell a million cars, save a dollar on each =.....
They do work and I've done filter tests in the past to prove it, but as you say typically the few bhp you get you won't feel, but then thats never how power mods work, you don't find 30 bhp you find 3 bhp ten times.
Also, an air filters' restriction depends on both its filtration level (i.e. how big the holes are), AND the surface area. Look at a paper air filter, and how much surface area there is - there are a LOT more pleats. Generall, a paper filter will have at least 3x as much surface area as a cotton gauze filter, usually a lot more.
I actually tested the restriction on my MR2 Turbo - it came with an Apexi induction kit. I replaced it with a standard airbox, and paper element. The restriction was lower with the standard intake system. The standard system also got much lower intake temperatures, as it was ducted to the side inlet.
I'd have one on an off-roader in adverse conditions, or a rally across a desert, they make total sense, or an old car with carbs that would normally have a crappy pancake filter and a 1" intake trumpet, but a modern car? It's just marketing junk.
If there were meaningful gains there, in today's Euro emissions targetted, c02 rated, mpg scrutinised age, then the manufacturers would fill them... well for the last decade I think they already have been. It's a long while since I've seen a poor intake system on a car. If there were easy bhp to find because of a cheap filter element change, they would do it!
This is the age where 'eco' models get specially developed tyres and aero (can't be cheap) just for a few more mpg!
Dave
I always thought that the point of an oiled filter is that it traps dirt through adhesion rather than filtration. A paper filter catches particles because the holes are smaller than the particles it's supposed to filter. What this means is that every particle caught a hole is blocked and air flow is reduced. It also implies that there's a limit to the size of particle it can filter out. An oiled filter traps dirt because it hits an oiled surface and sticks. This means that the smaller particles stick too and no holes (which are a lot bigger) are blocked. When both are new you imagine that the peformance is more or less the same but over time the paper one will flow less air than the oiled one because the holes are getting blocked whereas the performance of the oiled one should remain more or less constant. I would have thought you only need an oiled filter if you think you'll reach the point where the decreased flow over time of the paper filter will be significant in your application before you intend to change it.
Check out the filtration properties of this aftermarket filter then:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
eliot said:
Check out the filtration properties of this aftermarket filter then:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Nice!http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Anyone here supporting these types of filters ever done their own side by side tests with an OEM setup?
I've done lots on my last car, and everything aftermarket was crap and expensive, and that was a diesel 306 HDi. Imagine what a more modern powerful car will have spent on it's intake setup!
Dave
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