Is K&N air filter good for S80 ?

[Volvo S80]

Hi i`m thinking to put a K&N air filter in my S80 the factory says that the engine will get more air with K&N which helps the engine to run smother,to increase the power ,fuel economy and also if the filter is washed every 15000km and lubricated it will last 1600000 km , can anybody that used one share any opinion about the benefits of this product and does it cause any problem to the engine ??

[JDS60R]

No benefits as the filter is already properly sized. Use a Mahle replacement filter and do not change it again until fuel mileage drops.

I have tried them myself as well as many Volvo owners I know. I have several unwanted ones for cars and motorcycles up on my shelf. I once believed they were great too. But time and actual data has proven otherwise. K&N will advise you that 5 square inches of their media will flow the same as an off the shelf filters 6 sq inches of media. So on an undersized airbox there is an advantage. But 2 things are now true for your case.
1 Your airbox is properly sized.
2. Top end companies are now producing nano filter media which is a smaller thinner wire in the matrix. This allows better filtration, more holding capacity and much better filtration from the start as well as through its life, included is enhanced flow that now equals or supercedes the old 5 to 6 rule on a K and N.

I am sure someone will post the flow per square inch formula for a cellulose filter so you can calulate how oversized the airbox filter is.

Please check for any broken airbox thermostats or controls, Dirty MAF sensors, oxygen sensors over 100K miles in service and dirty air or fuel filters. If everything is at stage 0 you will get great economy and power. Please make sure to run top level sythetic oil and transmission fluid to unleash power and protect your investment.

[JDS60R]

Formulas
Square inches of filter required for a motor = CID x Maximum RPM / 20839

CFM required for a 4 stroke motor = CID x Maximum RPM / 3456

CFM required for a 2 stroke motor = CID x Maximum RPM / 1728

CFM required for a turbocharged or supercharged motor = Pounds of Boost / 14.7

Add 1.0 to this answer. This relates to #2 and #3

Example: (CID x maximum RPM x #4 ) / 3456 or 1728

To find circumference of a circle multiply diameter by 3.1416

To find diameter of a circle multiply circumference by .31831