Project S4: K&N Air Filter

Having had great success with a simple air filter swap from the OE manufacturers paper unit, to a high-flow replacement panel filter before, we’ve decided to fit a K&N High-Flow FilterCharger® version to the Project S4 ( I have dyno checked panel filters versus cold air induction kits of a number of different project cars over the years and found that – assuming the airbox is off good design (and the S4’s is, buried deep into the front wing, away from heat soak from the big V6 twin turbo) – they tend to produce better gains. They are cheaper too, and require a lot less maintenance. They are a proper “fit and forget” modification, especially those from K&N – coming with a 1,000,000 mile guarantee, making them great value for money long term (think how many standard OE paper units you would need over such a mileage!).

K&N say their air filters are designed to:

•  Offer high air flow with excellent filtration
•  Increase horsepower, mid-range torque and acceleration
•  Be washable and reusable
•  NOT void vehicle warranty
•  Last up to 50,000 miles before any cleaning is required (depending on driving conditions)
•  Come with K&N’s “Million Mile Limited Warranty®”
•  Be emissions legal in all 50 US states
•  Be economical: A K&N Air Filter Will Last the Life of Your Automobile, Motorcycle, or ATV
•  Work with Original Equipment Manufacturer vehicle electronics
•  Be an easy high performance add-on
•  Be environmentally friendly.

What’s not to love?

K&N add: “The K&N FilterCharger® air filter is designed to achieve high, virtually unrestricted air flow while maintaining filtration levels critical to ensure long engine life.  Our automotive OE (original equipment) replacement air filters generally add 1-4 horsepower. The secret to our success lies in the unique characteristics of our filter medium that was originally developed by K&N all those years ago in the dust, sweat and tears of desert motocross racing.  We just wanted to win races and stumbled on a cotton filtration technology destined to be great.  Our high flow cotton gauze air filter is washable, reusable and built to last for the life of an automotive or motorcycle engine.  K&N air filters consist of four to six sheets of cotton gauze layered between two sheets of aluminum wire mesh.  This media is then pleated and oiled to enhance its filtering capabilities and overall performance.  K&N Air Filters were created for an environment requiring maximum horsepower and enhanced acceleration in addition to protection from the dirt and dust of off-road racing.  The result is an air filter that allows dramatically more air into an engine, is washable and reusable, and will protect your engine for the life of your vehicle.
Engine Protection, Filtration
Anyone can flow more air.  The trick is to flow more air safely.  In our opinion we hit the sweet spot – an optimal blend of high air flow, filtration efficiency, durability and dust capacity.  We take filtration seriously.  K&N Air Filter media has been tested both in-house and by independent labs using the ISO5011 test developed by the Society of Automotive Engineers.  In addition we test many of our filters both in and out of the OE airbox ensuring proper fit and function.  Our goal is to design filters with the maximum possible airflow achievable while providing guaranteed engine protection.

K&N also preach “The Importance of Oil” saying: “A K&N Air Filter is made of 4 to 6 layers of cotton gauze sandwiched between two epoxy-coated aluminum wire screens.  The cotton is treated with a specially formulated grade of oil causing tackiness throughout the cotton’s microscopic strands.  The nature of the cotton allows high volumes of airflow, and when combined with the tackiness of the oil creates a powerful filtering media that ensures engine protection.  In contrast, most other media can not maintain the same balance of airflow and filtration throughout the filter’s life without sacrificing one or the other.  With a K&N Air Filter, there is no sacrifice.”

We will be fitting the K&N performance air filter very soon, and look forward to letting you know how Project S4 – with its back-pressure-reducing/gas-flow-improving, amazing Milltek sports cat exhaust system, boost-maximising/lag-reducing Forge blow off valves and awesomely-mapped Superchips ECU remap already in situ – responds.

More here soon!