Will simply replacing my paper oem air filter with a K & N air filter increase HP and fuek economy? or are those claims bogus?


Asked by Jun 25, 2009 at 03:46 PM about the Ford Mustang

Question type: Car Customization

24 Answers


Most cases, no they don't make gains, there are exceptions. I personally like 'em because they're washable, and save money in the long run. That being said I'm usually too lazy or busy to wash 'em. So I haven't actually gotten one from my newest car, and prolley won't since it's a daily driver and waiting for the filter to air dry after washing takes forever here in the summer (humid).

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Neither gains will be big enough to notice, but in theory, yes it will improve power. More air is more power. As stated above, the big upside to an aftermarket reusable filter is that they last for 1,000,000 miles and are easy to clean.


Yes, actually it will. Suprisingly enough, the filters have better air flow therefore increasing air to the engine, and increasing horsepower and fuel economy. The numbers are not huge, however the filters last forever if you buy the recharge kit, if so a simple wash, dry, and lubricant will keep your filter flowing easy. I would suggest going with the whole kit, wich should include the duct work going into the throttle body, depending what kind of mustang you have. though it is alot more expensive, it will give you more horsepower and fuel economy over just the filter.

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On a mustang, and perhaps for a lot of other cars out there, one way to actually feel an improvement when replacing your filter is to remove the air silencer bolted inside the fender. It's a plastic, snail-shaped doohickey that restricts a lot of airflow.

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i would need to see a dyno sheet to believe this.


you may want to look into a different filter than just a K&N also. sometimes they make the best products for certain cars but not always. find some independent studies on hp and fuel consumption increases/decreases. K&N gives bogus numbers as do most companies about their own products


Do yourself a favor and instead of just replacing the air filter that is in there with a more expensive K&N, buy a cool air intake...not to be confused with a COLD air intake. In non name brands the cool air intake will cost you between 50 and 100 dollars and are incredibly easy to install. They do remove the entire air filter and resonator, but they allow more air to flow with a conic Air filter that IS reusable when you clean it. It provides SIGNIFICANT changes in performance...the main benefit being throttle response and that really cool throaty sound we all love.

3 people found this helpful.

Well I do not have one :( But you can remove the one from your car and check if you feel any difference, it sure made my car feel a bit lighter. And if it doesn't you can just bolt the silencer right in (note that I am talking about the silencer and not the airbox, tho you would need to remove that one as well to install a conical filter). I'm including a pic of both, the stock airbox (left) and the silencer (right) so you can see how restrictive the design really is. My current setup is a K&N 75mm fender mount CAI with a Big Mouth UPR filter


proper air flow is just as important as the amount of air also. more turbulant air entering the chamber is less effective then less amounts of air with proper flow. like i said i would need to see a dyno sheet to prove that removing this stuff helps.


That's cool, tho I don't see many people spending money on dyno time to test an air filter and removed silencer. At least for the guy who started the thread it should be worth a try


just changing the air filter will give marginal horsepower gains ( 1-8hp)depending on the vehicle. Go to the K and N site to see their specs pertaining to your vehicle.


they actually do increase fuel economy, dont know bout hp but even if it doesnt increase hp, its always important to hav a good air filter


their specs they put up are all FALSE. dont go by those.


YES absolutly. certainly on your mustang usualy about 10% you will also hear the diference! even on my 4 cyl Honda it made a noticable diference as i pull a trailer with it!. The only way it would not make a diference is if you already had one! and just changed brands...I have one on my 69 mustang as well


it will increase power and fuel economy but i would look for one with the fenderwell kit, because the k&n kit that i got is i the engine compartment with no box so i sucks in the hot air. i see lots of kits designed loke this and i have no idea why


Just the filter change alone will probably not show any real difference, using the K&N CAI unit will make for a louder and more responsive motor. There may only be a small actual horsepower increase but the throttle response will be much better. The K&N unit is expensive, and doesn't seal out all of the underhood heat, but it is made from a plastic which means it insulates the incoming air. Many of the less expensive models use a shiny metal tube which looks cool but does conduct heat so you lose some of the advantage of the fender mount filter. I think the result is that they both offer about the same real advantage but the in-fender models are often much cheaper (as has already been pointed out). I am about to purchase a new intake for my 1999 V6 and I will probably go with the less expensive unit. I don't expect any real gain in power, just a very pleasant intake sound and crisper throttle response, which is just fine with me.

Depends on the application, the typical 5hp gain isnt going to be noticable. On a 2001 mustang gt, replacing the filter adds just under 6 hp. replace the whole intake arm and it bumps up to 10 hp (dynoed on both) but dont stop there. Some of the best cost-effective gains you can get is by changing the intake manifold. If an aftermarket manifold isnt available, consider alternatives like boring port sizes and extrude honing cast metal manifolds to remove the rough internal surfaces. (if you dont know what extrude honing is, think abrasive silly putty shot through the manifold to sand the insides.) youll need to tune your vehicle to get the most from the intake (SCT handhelds work great for this typically about $400-$500)


if u want to add hp by changing the air intake the best way is to get a cold air intake but it wont help alot unless u change the oxegen sensor on your throtle body


K&Ns are a big rip off. Others out there are cheaper..And more air more dirt. They suck the oil out of the filter medea and screw up the MAF and MAP sensors in your intake. Will void your warrenty..


Check this out.http://www.bobistheoilguy.com/airfilter/airtest3.htm

2 people found this helpful.

i think that K & N are crap because the oil messes up your engines sensors. i prefer to use spectre brand air filters.


it will effect you fuel economy more than anything really. and for the guy who said it messed up his sensor its because when you recharged the filter you put too much oil on it. thats the most common mistake is that young kids get them and they over oil it or dont let it dry enough and end up shorting out a IAT sensor or MASS sensor.

If you over oil it, yes it will screw up the MAF sensor and kick on a check engine light.. but you can invest in a bottle of CRC MAF sensor cleaner for $8 and take care if it.


I agree they will help a little with power and throttle response. And you never have to buy one again. I've put one in 2 of the 3 5.0's that I've owned and they work well. Just be careful not to over oil or you will have to use the mass air sensor cleaner to to remove the excess oil off the MAF to keep check engine light from coming on.

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