Air Filter Overview

This is not going to be a Thesis on automotive air filtration but just a few notes.
An interesting note on filtration. Some of you are not going to like this but try to keep an open mind.

When filters are new, they flow more air. Makes sense, when they begin to collect dirt, they begin to filter better. Ok I guess that makes sense also. The filters start collecting a very fine lawyer of dirt like you have probably seen on small fans inside your computer. This fine layer of dirt actually helps to increase the filtration of your filter.

AND if you change your filter, before it has started to reduce the amount of air flow to your engine in the amount that could make a difference in performance, your are throwing out a better air filter than then the one you are putting in. Kind of sucks doesn't it? You thought you were providing better care for your car by changing that air filter LONG before the recommended service requirement.

Ok let's look at it a different way, no matter which air filter you use, it is designed to flow air and capture dirt. It should allow MORE air than your engine needs for the recommended life of the filter. The dirt that it captures contributes to the filtering capability, meaning it will filter out SMALLER particles. So your new filter looks pretty, you feel good about taking care of your baby and you have just put in probably a worse filter than you took out.

From my research, it seems that you need around 6,000 miles before the air filtration starts to improve and will continue to improve. Course when you hit around the service life of the filter, you are getting in the neighborhood of restricting airflow enough to make a difference in performance.

And then you are right back where you started, needing to drive 6,000 miles to get the filtration quality back up. Little light bulb here, remember the oil/cotton people tell you to not to clean it all the time. I bet you they know about this.


Some people like to call it cellulose, I guess it sounds more technical. I call it paper Currently the vast majority of vehicles come with a paper type air filter. It probably does a fair job and it is a lot cheaper for the Auto Manufacture to supply them on new vehicles, thus saving you about $5.00 on your $30,000 investment. Their selling points are, ahhh well everybody has them and they are cheaper than any of the other filter meda.
Lots of paper air filters out there, take your pick

Cotton/oil filters

For years, automotive enthusiasts, (gear heads, motor heads, ricers etc) have been using oiled cotton gauze air filters. Many people swear by them have had a lot of success with them. TEHIR selling points are that they are reusable, and that they stop more dirt because the oil attracts and holds the dirt better than a paper filter. By far the largest of these type are the K&N filters.

Synthetic filters

Synthetic air filtration has been around for years in other industries uses but it was not that long ago that they started showing up in numbers for cars.

Amsoil was one of the first that I had noticed, with a wide application of filters. Amsoil seems to do a good job of using numbers and examples so I am going to borrow some of their info to note some of the advantages and claims.

Here is their synthetic Nanofibers on top of a paper filter.

As you can see it clearly looks like it would filter out smaller particles of dirt.
They also claim that it holds 2.5 times more dirt than a paper filter and 15 times more than a wet cotton filter.

Amsoil also warranties their Ea air filters for 100,000 miles and allow you to clean them every 25,000 miles.
So you are not getting the million mile warranty like K&N but you are getting 100,000 out of it.

Filter sensors?

So how do I know when my filter needs to be changed. Well you can go by the miles driven just like your oil intervals.
Some vehicles have software built in that takes into consideration how far you drive and how many times you start your vehicle to give you a real world indication of when you should change your oil. Why don't we have something like that tell us when to change the air filter?

Well they have been using something similar on diesel trucks for years. It is a sensor that measures the amount of vacuum applied on the dirty side of the filter box. A restricted air filter will allow a larger vacuum to be created on the dirty side than on the clean side. The LARGEST amount of vacuum on a dirty filter would be created during full throttle.

There are sensors, about the size of the old 35mm film canisters, and you need to somehow get a vacuum line from the air box to this sensor, or mount the sensor on the air box. They will give a visual indication if the vacuum reaches too high. This means that you will need to check the sensor for the indication and probably you will have to have your foot down for a few seconds to get the reading. I need to check but I am thinking this needs to be under a load and doing it in your drive way will not count. BUT hey it might be a good excuse if you get pulled over for speeding.

Some of the fancy sensors come with a remote light that you can mount inside the car to let you know that you are probably about ready to get pulled over.

You can check this little gadget out here http://www.filterminder.com/. Just something to think about. At the very least it is a good reason not to spend money and time in changing the wife's car's filter.
More money for mods for you.

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