by Paul Williams
Many people are interested in improving the performance of their vehicle. Even those with high-powered cars, like an Audi S4 or BMW 330i, still crave a few extra horsepower.
Those of us with more mundane vehicles will take anything we can get.
Without using aftermarket tuning chips, or exotic and expensive superchargers, one of the first recommendations from most tuners is to increase airflow to the engine. The second recommendation is to maximize exhaust.
Let’s take a look at increasing airflow, as it’s inexpensive, simple, and an often-effective modification.
The easiest way to increase airflow is to switch to a performance air filter. The primary function of an air filter is to clean air before it enters the engine. The cleaned air is then combined with fuel using a fuel injector or carburetor. It’s that mixture that is ignited and powers the car.
Many competition cars don’t use air filters at all. Their owners just want to get the maximum amount of air into the engine. That’s because the engine’s power output is proportional to the amount of air it can ingest at any given rpm.
For the rest of us, it’s a compromise. Lots of air is good, but we want it clean, so we don’t damage the engine. The trouble is, most standard air filters tend to excessively restrict airflow as they clean it. That’s why a performance filter is a good option.
One of the most popular replacement air filters is made by K&N. Take a look under the hood of many performance-oriented cars and trucks and you’ll see the familiar K&N logo. Most of this company’s products are direct replacements for factory air filters and installation is simply a case of taking the old one out, and putting the new one in.
The difference between conventional filters and the K&N product is the material from which they are made. Standard filters are made from pleated paper consisting of compressed fibres. The spaces between these fibres provide microscopic holes the air must pass through which the air passes. The fibres block airborne particles.
Over time, the paper filter becomes dirty, and its ability to allow air through to the fuel management system deteriorates. At that point, the filter is discarded, and a new one installed.
K&N filters use oil-impregnated cotton fibres, rather than paper. The theory is that such a filter will allow more air through, while still effectively trapping dirt particles.
The company claims that 50% more air is passed through their filters, compared with equivalent paper products. Furthermore, compared to a paper filter, more dirt can be trapped without having a negative effect on airflow.
However, a K&N filter is more expensive than a paper filter. What happens when it gets dirty? Are you to throw that away, too?
No. You can clean and re-use the K&N filter up to 25 times without reducing its efficiency. The procedure is to remove the filter, clean and dry it, and then add new oil to the cotton fibers. Or you can have your technician do this at regular intervals, usually once a year. In normal use one filter should last for as long as you own the car, so make sure your technician doesn’t throw it out.
A step up from replacing the air filter is to replace the filter and the case in which it’s contained. For injected vehicles, K&N calls this a Fuel Injection Performance Kit (FIPK).
The FIPK provides a re-engineered air intake system that replaces the filter case without compromising emission standards. Typically the kit will include necessary heat shields, and improved hardware to smooth and straighten airflow. They all include an air filter.
K&N claims that its filters can add from between 3-10 hp, depending on the application. The FIPKs are claimed to add up to 26hp. Some people also report better fuel economy, but this is not something the company claims.
K&N products are available for a wide range of cars and trucks, even those of a non-sporting type. Prices vary. In general, if your air filter is a rectangular panel, like on the Ford Focus, expect to pay between $60.00-$100.00. If your car uses a conical or otherwise irregularly shaped filter, like an Acura Integra, expect a cost of $90.00-$150.00
Fuel injection performance kits range from $400.00 to $600.00.
You can also buy a service kit to recharge the filter. It contains a cleaner and spray oil, along with a decal that warns against discarding the filter. The kit typically sells for $16.95, but many service centres will keep a supply of cleaner and oil as part of their shop consumables.
K&N products are available from Canadian Tire, although for some vehicles they’ll be special-ordered (the items generally arrive in 48-72 hours). Smaller performance shops are also likely to carry K&N.