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TECH

Photos & Text by Vahok Hill

AIR FILTERS

WITH ANY ACTIVITY, there are always aspects of that activity that are deemed less than glamorous. In racing, mounting and dismounting tires and washing air cleaners are the winners in my book for being rather odious tasks. While neither is that difficult, the probability of being first on anyone’s short list of “fun things to do on a Thursday evening” is very low.

As with many other things we must accomplish in order to have a good day at the races, a clean air filter is a necessity not a luxury. If the air cleaner is clogged with dirt and grit from the past several race days the engine will not get all of the air it needs to do its job. That means you get less horsepower. Conversely, if the filter is omitted under the pretext that its removal will result in more horsepower, the owner will be treated to a trip to the engine builder to replace all of the moving bits that have worn prematurely. This will be due to the incoming air charge being a good percentage of dirt, grit and other nasty bits. That would be the best case in that particular scenario. What would probably happen is that some hard bit - a rock or other such debris - would invade the rotating internals and do some serious damage. That should read expensive damage.

There are two types of air cleaners that are mainstays of the racing industry and this spans from karts to sprint cars. 1) Cloth gauze between a wire mesh 2) Foam in various shapes and sizes. I have not included paper elements that are sometimes required in the various spec classes due to the fact that most opt to replace versus clean. The method for servicing the two is very similar. The need to purchase specialized cleaners and solvents is not always necessary. Yes, you read that right, no special cleaners or solvents are required. In fact, I would be willing to bet that you might have the required cleaner in your home now. If you do not, a trip to the local Supermarket, Wal-Mart, K-Mart, Target Lowes or Home Depot, might be in order. You will need some “tools” to accomplish the task at hand. You might like to buy a small soft bristle brush, and I mean that quite literally, you need a very soft brush and you do not want to damage the filter while you are cleaning. You can usually find these in the kitchen department in any of the stores I have mentioned. Nothing fancy, just a very soft bristle brush. Try not to invade the kitchen at home and rob one from there. Unless you enjoy the taste of oil. Additionally, you won’t make any friends on the home front either. We will break this process down into simple steps. Once the air cleaner is removed the process can begin.

1. With the filter removed, place a clean paper towel or rag in the carb, or air box (to be removed later this will prevent any dirt or other abrasive material from invading the engine). Gently remove any large particles of dirt or grit from the filter. Use care to not tear or damage the filter. If you are using an air box remove the filter after you have removed the airbox assembly from the engine. The airbox should be cleaned as with any ducting leading to the filter. Avoid cleaning the air box on the engine. This will help preclude the possibility of loose dirt clumps from finding their way into the engine as you wrestle the air box from its mounting position. 2. Examine the filter for any obvious damage. If the filter element is torn or the areas around the point of attachment are cracked or damaged discard the filter. It is not even worth cleaning. 3. Soak the filter in a solution of a mild detergent and water. There are many varieties of soaps that are suitable for this job. Simple Green works great for cleaning the dirt from filters and it is available at a wide range of automotive outlets and in the cleaning sections of most big box stores and can be obtained in most auto parts stores. Wal-Mart and K-Mart carry similar types of soap. Even regular dish washing soap will work for this purpose. Dawn dish soap works very well. It is called Dawn Ultra or the whole name is Dawn Ultra Platinum Powerwash. This stuff works very well in loosening dirt from the oil in the filter. There is no need to buy special soaps that have only one purpose. DO NOT use gasoline or any other petroleum-based solvents to accomplish this task. There are several reasons to avoid the use of gasoline to clean filters. First, it is very dangerous. The chance of a fire is great. Second, gasoline is a poor solvent. It does a poor job of cleaning filters and it may even damage some filters. You have been warned. The reason for soaking the filter is to loosen any dirt or debris that have been trapped by the filter. Just mix the soap in a clean bucket with water. Just enough water to cover the filter. The five-gallon buckets that all of the major home repair warehouses sell work great as a portable sink for cleaning air filters. I prefer a white bucket as it helps you see just how much dirt you are removing and when dirt is no longer coming out of the filter. 4. If you are cleaning the K&N type of filter, just grab the inlet spigot and swish the filter around in the soap solution. If you are cleaning a foam filter, do the same thing. The foam filter can be gently squeezed to help flush out any particles. This will help dislodge any of the more stubborn particles. Remove the filter from the solution and rinse in clean clear water. 5. Empty out the solution and repeat the process. You will be amazed just how much dirt is in the filters that would otherwise be in your engine. 6. On the second time through the solution, you can use your soft bristle brush. This type of brush is only to be used on the K&N type filter. Gently stroke the brush on the outside of the filter. The goal is to use the soft bristle brush to dislodge any stubborn dirt. The foam filter will not survive a good rub down with

a brush. Just a note on the K&N style of filter. If you want that new look and the gauze to be white and pristine looking, K&N makes a special detergent for washing this type of filters. Formula 409 kitchen cleaner will do the job just as well. If you are the real laid-back type of racer this type of filter (K&N) can be cleaned in the dishwasher on the fine China settings or a very gentle setting once all of the big clumps of dirt are removed. I used to do this when I was a bachelor. If you are married and would not like to be a bachelor again, I would not recommend this method without clearing without other ruling members of the household on board with the use of the dishwasher as a filter cleaning method. This method can cause some tense times in the house if everybody is not in agreement over this method of cleaning filters. However, the filters look like brand new upon removal from the dishwasher. Just place the filters on the glass rack and wash with regular dishwasher soap. I like the kind in a squeeze bottle. Remember; forgiveness is often granted when permission is not, sometimes. You have been warned. 7. How will you know if the filter is clean? You can verify this in two ways - looking in the bucket you are using to wash the filters and looking at the filter. If the cleaning solution is a different color than when you started, it is still getting dirty and you have not removed all the dirt. Carefully pour out the solution and look for any grit in the bucket. If there is still grit in the bucket you can be pretty sure that there is still dirt in the filter. 8. Rinse the bucket out and repeat the process again. Do this until the water is still clean after you have thoroughly agitated the solution with the filter. 9. Rinse the filter out in clear water. You can just use a garden hose for this activity. Do not use any high pressure or spray nozzles to rinse the filter. The higher water velocities could damage the filter element. 10. After you have rinsed the filter and have removed all the soap residue from the filter it is time to dry the filter. DO NOT use compressed air to blow the filter dry. This could damage the filter in much the same way that spraying high-pressure water through it could damage the filter element. Just place the filter in the sun and let it dry. If it is the dead of winter and it is cold out side just place in the house (ask permission) on some newspapers. It should be dry by the next day. 11. Now it is time to re-oil the filter. For this task, I would recommend that you use the oil that the manufacturer recommends. It is not that expensive and a can or bottle of it seems to last for years. You are not gaining anything by using filter oil that is not recommended. DO NOT re-use the filter without oiling the element. The filter was designed to be used with the oil on the filter media. The elimination of the oil reduces the efficiency of the filter. The oil helps in the trapping and holding of dirt in the filter.

The care and feeding of your race engine will go much smoother if you feed it a supply of clean air. Keeping the filter clean and oiled per the manufacturer’s instructions will make that a much easier proposition. See you on the podium.

Vahok has spent 30 plus years writing technical articles exploring the ins and outs of mechanical processes as applied to race cars. He has traveled the world looking at mechanical and machining processes. He has been actively involved in racing for 40 plus years in off road racing, kart racing a variety of short track racing from cars to motorcycles to sprint cars. He was involved with the introduction of computers to race cars when that form of data acquisition was still something that was not the accepted norm. He lives and breathes all things mechanical.