The 411 on Air Filters
Every automobile engine has an air filter in order to run properly. Most engines run on an air to fuel ration of 14:1 for general driving. That means your engine has to breathe 14 times more oxygen than fuel in order to run at maximum efficiency. Air filters keep the oxygen relatively clean by trapping dirt particles, as well as keeping contaminants off the airflow sensor. It also helps to quiet your intake system. Your engine can use up to 40,000 litres of air for every 3.5 litres of fuel burned.
Imagine going for a run in a smoggy, soot filled city. Now imagine that run while wearing a nice clean air mask. Oxygen delivered though a clean air filter will help keep your engine running properly – while a clogged or dirty air filter can strain and starve your engine of air.
Air Filter vs. Cabin Filter
There are two types of air filters with completely different uses on your vehicle. An engine air filter is for the engine while the cabin filter cleans incoming air for the car’s climate control system. Cabin filters trap pollen, bacteria, dust, and exhaust gases that find their way into the ventilation system. A clogged cabin filter can cause interior heating and cooling problems; for this reason your repair facility should be inspecting the cabin filter each time your vehicle is in for scheduled maintenance.
What’s the Catch?
We all know what the front of our vehicles look like after they’ve been driving on a warm summer’s night or a slushy winter’s day. The license plate and grill of your vehicle is usually splattered with bugs, dust, and other debris from the roads. That, and water, can end up in your engine area. Fortunately your engine air filter catches microscopic bits of bugs, soot, dirt, sand, salt, leaves, straw, and tiny bits of rubber before they makes it to the engine.
A good air filter will keep out 99.5% of all particles that make it into the engine intake.
The Risks of Running Dirty
Every engine needs three basic things to run properly: clean gas, clean air, and healthy spark to ignite the air/fuel mixture. If one of these fails, you have a problem.
A dirty air filter will reduce engine power output. To make up for lack of oxygen, it adds more gas. This in turn decreases your horsepower as the air to fuel ration won’t be correct.
Clogged filters can choke an engine and will affect the emission control system which, in turn, could result in fouled spark plugs. A dirty filter equals a rich fuel mixture which can cause increased engine deposits. It can also allow dust, sand, and other particulates into your engine. Something as tiny as a grain of salt can result in costly repairs if it gets into the internal parts of your engine.
Some studies indicate by replacing a dirty air filter on older carbureted cars you can increase fuel mileage by 14%. Fuel injected cars have been shown to increase acceleration from 6 to 11%.Considering the cost of an air filter, it just makes sense to have it regularly checked and changed when dirty.
Types of Air Filters
There are several types of filters on the market, one of the most common being paper filters. Within the paper filter category there are top quality filters and poor quality filters. At Motor Werke, we’ve been consistently happy with the quality and lasting performance of such factory replacement brands as Hengst and Mann.
The fibers in paper filters are tightly compressed and dense in order to trap particulates. As a paper filter gets clogged and dirty, the pressure inside the filter drops while the atmospheric air pressure (approximately 14.7 psia at sea level) outside the filter remains the same. The airflow through the filter and its ability to protect your engine decreases greatly near the end of its service interval.
There are foam air filters out there; however, they are inefficient in their design as open cell foam is easily saturated with oil, and as dirt builds on the filter, cells become blocked and airflow is reduced.
Reusable air filters are designed for optimum performance. At Motor Werke we prefer to use the K&N brand. Reusable filters have multiple layers of oiled cotton fabric that capture dirt particles, which in turn cling to the fibers of the filter and become part of the filtering media.
This process is called depth loading and enables the filter to trap and retain more dirt than a paper filter. The cotton fabric, sandwiched between a pleated aluminum screens, exposes more surface area compared to a flat element like foam.
As the filter collects dust and debris, air must first pass through the dirt particles trapped on the filter’s surface. The result is the reusable air filter continues to have high airflow throughout the life of the filter, even as it gets dirtier.
Reusable air filters are washable and can be cleaned and oiled with a recharger kit; it is critical to educate yourself on the proper process of recharging a performance cloth K&N filter. If the cleaning and oiling process is performed incorrectly, the air mass/air flow sensor can become contaminated and fail as a result.
Depending on your vehicle, a reusable filter can reduce the cost of buying disposable filters and canisters, and as there is nothing to throw away, it’s better for the environment.
Time for a Change
When to change your air filter depends on how dirty it is, not how many kms you’ve driven. A filter that lasts 20,000 kms for city and highway driving may only last a month on country roads or in a dry climate like the Okanagan Valley.
Removing the filter and holding it up to a light will show you how dirty it is. Unlike your household vacuum filter, you can’t shake or blow off the dirt on an engine air filter. When in doubt, ask the Kelowna European auto experts at Motor Werke to advise you on when to replace your air filter.
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