K&N AIR INTAKES. Do they REALLY work?

Question

Some ads. claim that the K&N air intake systems increase performance. Is it true and what kind of performance increase would it be? And how hard is it to install the system?

Answer 1

Joe-

You are getting a little misleading information here after reading the other respondants.

Lets clear the air.

The K&N Cold Air Intakes are a great item to place on your car. They do increase the power output of your engine, but contrary to what the other folks said they DO NOT INCREASE GAS MILAGE.

The Cold Air Intake is about only one thing. Horsepower! That is it in a nutshell!

Here is how they work.

The stock intake systems in most cars draw air from inside the heated engine compartment. This warm air is introduced into the intake system to help vaporize your fuel charge going into the cylinders of your engine.

The warmer the incoming air, the less fuel needed for form a volitile vapor mixture entering the combustion chamber to be burned. Idealy the fuel mixture entering the cylinders should be 14.7:1. Or 14.7 parts air to 1 part fuel. The warmer the air is the less fuel mist is needed to vaporize into that mixture ratio.

So how do we make the mixture have more fuel?

By adding a Cold Air Intake System that draws the air from outside the engine compartment, through a more efficent duct that allows for a higher volume of cold air to be introduced.

Lets back up a little bit so you understand a little more about what is happening with todays cars and trucks.

In the past the way to introduce more air to get more power was to pass a larger amount of air through the Carburetor's throat called a venturi. The more air forced past this device, the more fuel would be drawn out of the jets and vaporized before entering the cylinders to be compressed, ingnited and burned.

Today most vehicles are made more like a Diesel Engine than the traditional gasoline engines of past years.

This Fuel Injection era has allowed more precise control of the fuel distribution to each cylinder to ensure that the engine efficency as a whole was increased.

So how do we get more fuel out of a system that is computer controlled to deliver only a precise amount of fuel at each injector?

We tell the computer that it needs to deliver more fuel by tricking its sensors into thinking there is a greater demand than there really is.

In today's cars there are several sensors that control the amount of fuel being introduced by the Fuel Injectors. They are: Manifold Absolute Pressure Sensor, (Measures Manifold Vacuum), Throttle Postion Sensor, (Measures the position of the throttle plates), Mass Air Flow Sensor, (Measures the amount of incoming air), Intake Air Temprature Sensor, (As it's name states), O2 Sensors, (Measures the amount of Oxygen in the exhaust gasses), Fuel Pressure Sensor or Regulator, (also as its name states) and finally Coolant Temprature Sensor to measure engine temprature. Additionally there are a few other sensors, but these are the main players here.

In some vehicles if they are equipped, (Boost Sensor), for the Turbo Charger, Electronic Waste Gate Controller, (Turbo Charged Vehicles), Intercooler Temp Sensor, again Turbo Charged Vehicles.

So by introducing air from an alternate source that provides a colder air charge, we need to have a denser concentration of fuel introduced into that air charge to properly ignite it after its been compressed in the cylinder. Because we have now introduced a denser air fuel mixture, we create more power from that source.

Additionally, we can add Turbochargers and Superchargers to even further increase the air flow past these sensors increasing the demand from the injectors until they can physically move no more fuel. In this case new and larger injectors are installed and the process repeated, until the computer cannot deliver any more fuel. Now it is "Chipped" and normally the fuel pump replaced so the volume can be increased to meet the demand.

There does come a point where the engine's volumetric efficency has reached its peak, then a larger engine is installed and the process repeated until the desired effect is reached, (NHRA Top Fuel Dragsters).

I use that example because the engines are limited to 510 Cubic Inches of Displacement, (510 CID). Because of the severe modifications and the type of fuel they burn, (Nitro Methanol), these engines are capable of producing over 5000 horsepower and sending the Dragster to speeds exceeding 275 MPH in 1/4 mile or shorter.

Just to give you an idea, your best time in a quarter mile will probably be about 12 to 13 seconds. They are doing this distance in under 5, (average is about 2.5 seconds).

Fuel consumption:

30 Gallons in 1 minute under full throttle.

Fuel Line Diameter:
2.5 Inches.

So with the race only lasting 2 or 3 seconds.

The cold air intakes are awsome. But don't expect to get better gas milage from their additon to the system. You are increasing the engine's ability to create more power more efficiently. This has nothing to do with getting better fuel economy. It just means that you need to use less throttle pressure to get the same results.

I hope that cleared up any confusion you may had over this issue.

Oh Yeah, don't let this discourage you from getting a Cold Air Intake either. I have them on both of my cars!

Zoom, Zoom, Zoom!

Answer 2

First, if you compare the performance of one of reusable drop in replacements to the performance of the same vehicle with a brand new paper filter, you will see no difference whatsoever.

Second, if you have a newer vehicle with a MAF sensor, chances are good that your dealer will refuse to do any warranty work on the MAF sensor. GM has already issued a bulletin on the contamination that occurs from these cotton based filters. It's not only the oil from the filter that fouls the sensor, but the cotton fibers as well. It's a real problem that you should be aware of.

Third, if you want a resuable filter, buy a Fram SynWash. It's a washable synthetic non-woven material that doesn't use oil or shed any fibers. You hose it down with a garden hose and detergent, let it dry and put it back in the vehicle. The polypropylene material has a positive magnetic charge that attracts the negatively charged dust particles, so it doesn't need oil.

Fourth, a filter has to do a balancing act between filtering out particulate matter on one hand and not restricting air flow and volumetric efficiency on the other. The theory in a cold air intake is that they can do both because of the greater surface area of the cone shaped filter. Where the theory falls apart is that volumetric efficiency fluctuates depending on throttle position, air temperature, RPM range, etc. So, if you're going to be driving all the time at full throttle, then a cold air intake will probably give you more performance. But if you're doing city driving, my opinion is that you will never recover the cost of this system through better gas mileage.

Finally, if you do a search of your car's make and model and add the word "forum" to the search, you'll find websites that specialize in that vehicle. Then do a search within that site for these filters. You will see entry after entry of people who have bought these filters and swear they didn't improve anything.

Bottom line, Detroit is under INCREDIBLE pressure to increase gas mileage. Don't you think that if they could save their behinds by installing an oil soaked cotton filter they would do it? Beware of things that sound too good to be true.

My opinion.

Rick

Answer 3

Do Cold Air Intakes Work

Answer 4

Not a whole lot of performance and to install is pretty easy. IMHO I would not bother, unless I am ramping up my engine and do the whole thing as a package. If you noticed the people that actually uses it and they are serious about it, they mod more things on their engines. What you see is an advertisement campaign. The real numbers comes from the Dyno.

Most cars and if you take the time to see, they have a passage to the clean air outside. Is somewhat concealed in the way the air box looks. If you see the actual air filter on a car is larger, giving you a bigger surface area. That will keep more clean air during maintenance intervals. Also the cars where designed on range of weather conditions, dusty areas, extreme cold, extreme heat and such. So if you drive on those types of conditions a K&N will clogged PDQ. If the filter stays outside of the car and it rains it gets wet therefore does not let the air pass through like it should. So that funky piece of Air Box that people removes is designed also to keep the water away.

They are engineers that gets pay good money to think on these things, and there is a reason why is there.

Is your money, if you want to buy it is ok but do not expect a whole lot.

Answer 5

People tell me that they do. They also have a cleanable element that can be reused. The power may come from a little cooler air to the engine and less restriction through the intake. One downside of this, if it matters to you, could be increased intake noise in the cabin. Some people like it that way, they can hear the air being sucked into the engine.

Your call, it's your ride. good luck.

Answer 6

Yes they do increase performance,and sometimes improves gas mileage. Any high flow air intake systems do this, as long as they are piped right. The idea is to take in cold air not the hot air from the engine. My intake is routed down to my fender down to my bumper infron of my front left tire. Some people put in short pipes and the intake is right next to the engine with out a heat shield. It does them no good, heat is bad for your engine performance.

Answer 7

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I agree wholeheartedly with MACH 2's analysis of KN's uselessness and harmful effects to a BMW engine. In addition, I would like to repeat for the hundreth time for those who still use this product that BMW has issued a Service Bulletin specifically saying that this kind of products will harm the engine (cause check engine lights) and that repairs for these are not covered by warranty. Kudo's to MACH 2's in-depth discussion of the subject.

Answer 8

real word experience...(i own 4 cars and have 5 k&n filters!)
i usually pick up .3 to .6 mpg, and a slight performance increase. i do not use the cold air kits, just the replacement filter elements. the higher the power of the vehicle the more noticealbe the difference. my toy el camino makes a HUGE difference paper vs. k&n....but at 400 horsepower to the wheels thats not the average car.
i like em.

Answer 9

Yes they do increase performance. Probably not 10% horsepower like commercials say, as those results are from perfectly tuned cars in perfect condition.
But it does add performance as well as can save a bit of gas money. They are fairly easy to install if you are a bit mechanically inclined

Answer 10

excess engine heat in hot summer days with a/c on then K and N cold intake might suck in hot air. or highway driving in down pour and water get sux in.