Performance air filters vs original paper air filters

Car owners who love extra performance will often explore getting more power via an air filter upgrade as it is commonly believed that a faster flowing air filter will yield more power. More air entering the engine at a faster speed does help improve combustion which in turn helps to increase power. However not all after market performance air filters live up to their expectations. Switching to after market performance air filters can yield up to 10hp for certain vehicles while others may yield only 1 or 2 hp. Turbo charged and super charged engines will benefit the most from higher flow air filters as forced induction needs fast flowing air supply. For naturally aspirated engines swapping to higher flow performance air filters will only yield at most 3hp as the nature of the engine can only benefit a limited amount of extra air.

When people talk about performance air filters most layman who knows a thing or two about car performance parts will know K&N. It is by far the most well known after market air filter brand in the world.
It is without a doubt good product but it is only good when it is brand new. Its concept of using a cotton based air filter is definitely better than the original factory fitted paper air filter which is not washable and is easily clogged. K&N air filters offer good filtration and coupled with the fact that it is made from cotton it is a lot more durable and last much longer than any paper air filter. The problem with K&N air filters come when you have to wash it and re-oil it. K&N uses oil to trap the finer particles of dust that the cotton filter may not trap. The oil has its advantages and disadvantages. Advantage is when the air filter is brand new, the oil is very effective in trapping dust and the oil is evenly applied at the factory. The big disadvantage is when you wash it and have to re-apply the oil which done by hand is extremely difficult to apply evenly. Lumps of oil will congregate at certain parts of the air filter and most people will apply too much oil which leads to blockage of the air filter and also over time it will foul up the air mass sensor.

Other variants of performance air filters are also available such as sponge or stainless steel. The famous sponge type air filter is available from HKS and Piper Cross. The sponge filters do not last as long as cotton as once it gets wet, it will break into tiny bits over time and enter the engine which can potentially cause problems to the engine.

The last variant is the stainless steel type which is far more durable than all other earlier types but is more expensive and needs regular cleaning for optimum performance. Stainless steel type of air filter is quite rare and only a small handful of manufacturers produce this type of air filter.

Air filter shape and design also plays a part in performance of the engine. A typical engine will usually have a flat panel air filter and after market suppliers offer cone or cylindrical type air filters. It is not guaranteed that upgrading to a cylindrical or cone type air filter will yield the necessary power gains as expected. For certain cars such as the VW Golf Gti, changing the original flat panel air filter to the cylindrical type will see power loss at low RPM as the absence of the air filter box means that when the throttle is open, there is no immediate air available and the air filter has to suck in air to feed the engine. This causes a lag and low end response suffers. The cylindrical type air filter in this case will only yield power gains at higher RPM.