Do Performance Air Filters, Cold Air Intakes & Induction Kits Work?

Get ready to wheeeeeelspin!!

Brum Brum. Squeeeal. Waheeeey!

At some point when owning a performance car, or if you're young, a slow car that you'd like to squeeze more performance from, the question comes up. How can I get more power out of this thing? How can I burn people off at the lights and generally feel like more of a boss, while attracting the attention of beautiful women?

Well one of the ways that you can do this, or at least so the marketing people tell you anyway, is to fit a performance air filter, or a full induction kit. A K&N or Pipercross, or something that looks like that but is unbranded, which you can get on ebay. Hey you can always put a K&N badge on the back of your car and get the respect of the rest of the barry boy racers so it's all good.

What's the difference between an induction kit and an air filter?

An induction kit usually comes with pipework, the idea being that you'll have the filter, which is usually cone shaped, situated somewhere it can suck in cold air, usually at the front of the bumper or somewhere close to air flow anyway. A filter without the induction kit is usually just put in place of the airbox and sits in the engine bay. Or there is the other type, the drop in filter, which is made of foam/gauze and sits in the air box, in the place of the standard paper version.

So, do these performance air filters work? The marketing bumph tells you that they will. I remember when I was a young man, with a low powered car and my friend told me that his friend had told him that you could get an extra 40bhp out of your engine with performance spark plugs and a K&N filter. I soiled myself on the spot obviously, that would have meant 50% more performance from my measly engine for practically no money. What a bargain. So I got the plugs and filter.

Before K&N

After K&N

How do they work? What is an engine?

These filters do work on a fairly simple principle. Engine power is created from fuel and air being mixed. If you put more of both in, then you'll get more powwwwwwwwwer. So the idea is, get a filter that doesn't restrict the air flow, or is less restrictive anyway and engine will then suck in air easier, the engine management system will provide more fuel and then the power/women will follow. Yeehah!

So, what's the problem? Is there one?

After driving cars with and without performance filters and noticing that the ones with the performance filters were louder, then I thought I'd do some reading. These filters do let a bit more air through. A bit anyway, in an independent real world test the top performing air filter on the market, the K&N filter let through 0.14% more air than a standard paper filter. Letting more air into your engine isn't what they're really good at though, they're good at letting more dirt into your engine. They don't really give you any more performance though which is the downside. Well I say no performance, that's not really true as you'll get 0.14% more. WOOO!

If you have the filter unshielded in the engine bay like this, then you'll lose, not gain performance

Hot air? Cold air? What's the difference?

The downside is that a lot of these filters come in a cone shape and requre you to remove the factory air box. Because of this they then suck air in directly from the engine bay which is hot. As you will no doubt remember from your physics lessons, air expands as it heats up, which means hot air contains less oxygen than cold air.

Less oxygen is not what you want from your air as this means that the air is less combustible, cold high oxygen air is what your engine craves and is the reason that turbo charged engine use intercoolers, you need to get that air cold before your engine gulps it down if you want to extract maximum power from it.

If you have an unshielded cone filter, then you will only be getting good cold air flow to the filter when you are going very fast, so there is a lot of air flowing into the engine. It's not practical to be driving at 100mph+ just to get a cold air flow, most of the time anyway.

You should hear it roar now I've fitted the induction kit. Aiight Ladies..

What this can mean is that until the air is flowing into your engine quickly enough to negate the heat soak from the engine, then you'll actually lose performance with a performance air filter. This will happen at low speeds and especially from a standing start. If you've been idling at traffic lights for 20 seconds, the air under the bonnet is very warm. You pull away and your car is down on power, until enough air has flowed in to replace the hot air. Not really what you want from a performance upgrade.

A drop in type that replaces your paper air filter directly in the air box won't suffer from this problem, but a cone will. Pretty much the opposite effect you're looking for when you buy one of these is less power, but if it's unshielded that's what you'll get.

They do make a louder noise though. Brum Brum!

This isn't fully shielded, but the bonnet sort of makes up the top of the box.

If you want to maintain the same level of performance that you get now, but have a louder noise, which to be fair can sound pretty good, then you'll need a full shielded induction kit.

I have included a picture of a filter that has been shielded to some degree, the bonnet closes off the box it sits in and it probably doesn't suck in too much of the hot air from the engine, or at least less than an unshielded cone.

Have you ever fitted or used an performance air filter / induction kit and how did you find it?

  • I have fitted one and thought it made the car faster
  • I have fitted one, it wasn't faster but it sounded good
  • I'd never fit one of those. I'm not a boy / girl racer
  • I like sausages
See results without voting

Something like this will give you the noise.

Here's the conclusion.

Although there is a lot of good marketing bumph out there, it is all unfortunately just bumph.You'd be far better off not getting a 'performance' air filter / induction kit and instead losing some weight from the car if you want a bit more performance. With an induction kit you will only get a louder noise and no noticeable performance increase, just your engine getting dirtier internally and if using an unshielded cone, then you'll have less power than standard.

My advice is just keep your paper filter regularly changed and don't worry about a high flow filter if you're after performance. If you must fit one, then make sure you don't leave the cone air filter exposed and instead fit a fully shielded induction kit to ensure that the air that goes in is as cold as possible. Only do it if you want the noise though, not as a performance enhancing modification as you just won't get noticeable performance increase, despite what K&N, Pipercross etc all claim.

Remapping, well that is a different story and something that will actually give you some real performance gains, rather than imagined ones with louder noise. If you want to read about that, take a look at the linked article below.

Thanks for reading, please leave any comments below!

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Comments 30 comments

dommcg profile image

dommcg 4 years ago

those look awesome, I think I might get one for my Volvo!

Rain Defence profile image

Rain Defence 4 years ago from UK Author

Nothing like a loud air filter on a diesel. Really accentuates the noise..

dbayern profile image

dbayern 4 years ago from North Carolina

They make a real mess of Subarus computers... can't get them to pass inspection with a reflash, and I still haven't seen any significant gain. May try one on my 71 beetle, might see 53hp!!! That's total, not gain.

chriscamaro profile image

chriscamaro 3 years ago from Ontario, Canada

I've got a K&N panel filter in my ram air setup and it amplifies the "whistle" that I already had. I don't mind... I think it adds character :)

Rain Defence profile image

Rain Defence 3 years ago from UK Author

Oh yeah, they might not make it faster, but you're right, they do sound great, especially on turbo charged cars where you can really hear them!

byshea profile image

byshea 3 years ago

These ram air filter kits actually cause more 'check engine' light problems than anything else. The mass air sensors don't like the change.

Rain Defence profile image

Rain Defence 3 years ago from UK Author

It's true. They sound good and I think that's the only real benefit. MAF sensors are very sensitive.

newusedcarssacram profile image

newusedcarssacram 3 years ago from Sacramento, CA, U.S.A

Hi, thanks for all the information. It was a good read.

Rain Defence profile image

Rain Defence 3 years ago from UK Author

Thanks for your comment

eroller profile image

eroller 3 years ago from Shanghai

Cool filter

jocent profile image

jocent 3 years ago

You're right it only gives good sound and little power because of faster airflow. Cold air is the one that helps increase boost and economy. The only thing you can expect from performance filter is the one time replacement. Thanks for the tip!

Magillacutty 3 years ago

I have a K&N rx-3900 on a short ram, with a cold air feed and heat shielded. Compared to my restrictive low flow factory air box I believe that my car (2.0t, 194 kw [atw], 1100kg, 18psi) spools up quicker and is more responsive on throttle. Look each to their own but I won't go back to factory... Oh yeah the noise!!! =D madness. Cheers Mgt.

Tom 3 years ago

True I've seen cold air intakes cause more problems then gains such as heat soak from the exposed filter under the hood and metal pipping, check engine lights, and cars going into limp mode. But they do sound nice on the car. Lol

honda-stream profile image

honda-stream 3 years ago from Canada

I love the sound of a good Air Intake! A nice little purr, the small performance increase is great too :)

Onlinestrategies profile image

Onlinestrategies 3 years ago

Thanks for explaining how the air filter works and why one should not change the factor fittings for obvious reasons.

john000 profile image

john000 3 years ago from Superior, Arizona

Thank you for the explanation about performance air filters. I have wondered about that, and you have satisfied my curiosity. Is the cone shape to start a venturi effect? I drive a 2.2 liter 4 cylinder truck. I love it because it is great on gas (for a pick up). Kinda pointless for me to buy a performance filter or induction kit just to hear a whistle like a jet! Everybody will still pass me when trying to pull a hill. But that's ok with me.

Good read.

Rain Defence profile image

Rain Defence 3 years ago from UK Author

I suspect the only reason they're often cone shaped is because of the way they look. A lot of manufacturers make them cylindrical as well. I can't see there being any real difference in flow between shapes, surface area is the only real factor with these.

I'm thinking of buying another v8 car soon and will probably get one just for the noise even if it doesn't make it faster!

Carlo 2 years ago

I run a K & N replacement filter not pod in my Turbo Mercedes and you definitely can notice a small gain in power and better response. Well worth $70.00, just need to keep it clean every 5,000-10,000kms.

Rain Defence profile image

Rain Defence 2 years ago from UK Author

Have you had it on a dyno or does it just 'feel' faster? Either way as long as you're happy, then it's all good.

Daniel 2 years ago

Well authored and answers a LOT of questions yet I have questions concerning cone shaped filters as I have found some sort of assembly on Ebay called [ 3" REAL CARBON FIBER AIR STACK FILTER/INTAKE HEAD SHIELD FIT MOST CAR 2.75~3.25 ] of which can be searched w/o the brackets and sorry for the long string but happy hunting.

-hey- think MAF sensors are crashing due to thermal issues? Try running them in the desert. Are there any ideas of people using heatsinks, air compressors, Freon - Air Conditioners to cool the air on the intake or is that a stretch of the imagination (at this point)?

The item depicted actually comes with or HAS a FULL CANISTER SHIELD. But is it a shield? Your article really has me looking for shields now instead of merely drawing warmed air into my intake. Sounds like a mistake! Will such a 5'' can made of carbon fiber aid in this battle of the thermals? I'm looking at 'the green shroom' pic under 'cold air intakes' and that um, kinda helps with the problem, but dose not fully answer the question. Thanks much!

Afterthought: I'm not concerned with the noise, though, if I had a choice (of mufflers?) then I'd probably try to keep a low-erd profile as I am not in the running for announcing STEAL MY CAR to the 'world'. If you know what I mean, great. If not, thank god. I'm really more concerned with heat shielding than grunt noise :)

KevSutton profile image

KevSutton 23 months ago from Gulf Shores, Alabama

great article very informative been messing with cars for years but sometimes forgot this fact. But like the race cars saying doing drag races. what they do is run a pipe from engine to the front fender so the filter is located outside the car itself so it wouldn't be heatsoaked. But now it's exposed to more pollutants but pulling more air in the for's like 70/30. not even 50/50. More harm would be done to the engine over time but it will give the race car driver a faster 1/4 miles which is the goal in race situation not really longevity. But for the everyday driver it's not necessarily the best option. And the gains are more seen with big horsepower applications like anything over 300 hp, then you have to replace the air filter of course. But that is not a standalone activity because the fuel system has to match up with the airflow if not your engine will be running lean too much air and no fuel to ignite the mixture. So yeah there is a few things to consider.....

Rahn Razamai profile image

Rahn Razamai 21 months ago from Rawang, Selangor

nice article. visit for car parts at reasonable price and good quality.

Farhan 21 months ago

This is certainly a good and informative article. Thanks.

P/S: To the user "Rahn Razamai"

You should've said that website is only for Malaysians. It killed my excitement when I saw it was in Malaysia only. *sigh*

Brandon 12 months ago

Cone filters are dumb. Most cars already come with a nice CIA intake. The most you'll have to do to make it "perfect", is to tweak the pipe coming into the air box to match the size of the one leaving it, and add a drop in K&N/Spectre panel filter. You'll get a bit better throttle response, which does make it feel more a little more powerful to the driver when you gun it.

ChrisCampbell05 profile image

ChrisCampbell05 12 months ago from Tampa, FL

some excellent points here. In most cases an intake will not make more power. That being said it can become necessary as other parts of the engine are modified.

Snapper 7 months ago

mmmm sausages.

Panel filters are the way to go and if you duct feed cold air direct to the air box you will get a few extra bhp.

Piper cross foam filter allows a lot more air to pass but any non paper filter will be better than standard.

In reality, you will struggle to notice 3% power increase.

Not Amused 4 months ago

....... Okay this article while having some ground is mostly crap. A cold air intake will increase power and throttle response, most cars computers require a tune to use them so the MAF sensor isn't freaking out. If you're have problems with a cold air intake chances are you're doing something wrong or just bought a cheap one off of eBay. Performance has so many components, but at the end of the day an engine is gas, air, and spark. You up the ratios on one of those you can get more power, it just has to be controlled.

Ron 3 months ago

I fitted the Pipercross to my wife's MX5 as we've just added simple things that actually improve the car such as the mesh grill to protect the radiator from stones. She wasn't convinced there would be any difference but, she says it actually feels as if there is just a little bit more power. She also likes the sound. It's not louder but just has a nicer growl that makes it easier to hear the engine for gear changes. So, that's the view of someone who had no faith ...

Ali 2 months ago

that's true. this what I got after fixing one of these air filter, noise... like I am driving and snake under my hood.... hhhhhhhhhhhhh

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