Secondly, the K&N filters are one of the most reliable systems for a performance car. If you are a lame mechanic and don't change the air filters when you should, an oiled foam element CAN give you some additional time to get to the thing and change it without doing some damage to the cylinder walls from dust scoring. The paper elements are superior to oiled foam IF THEY ARE REPLACED WHEN THEY SHOULD BE.
I'll toss in my personal experience.įirst off, there is no reason to install an oiled filter in the Prius as opposed to the standard paper element types. Test evidence that these filters, and that clog filters have no effect on gas mileage: I would prefer never to have to have my Prius's engine rebuilt. For racing cars which are rebuilt often this doesn't matter. Silicon is highly abrasive to the metal in engines and may increase engine wear and decrease service life. This shows as elevated silicon from road dirt. UOA have often shown that some oiled K&N filters may let in more dirt than paper filters. If one races a Prius than a K&N filter might make sense in order to win the races, otherwise it is a waste of money, or worse.
In this case a less restrictive filter will let in more air when the throttle butterfly valve is fully open, which will burn more fuel making more full power output. The only time a less restrictive filter has an effect is at or near full throttle. The fuel/air ratio is dynamically adjusted to keep it at what the car thinks best at the moment.Ī more restrictive filter will simply lower the air flow, and the car will compensate by either lowering the fuel flow, or slightly opening the throttle butterfly.
The reason it cannot improve gas mileage is that OBD-II cars sense both the amount of air, post filter, going into the engine and the state of combustion of the exhaust gas. All passenger cars sold in the USA since 1996 are OBD-II.
They will not improve mileage on a closed loop OBD-II car. You cannot have your cake and eat it too. If you take advantage of added power by driving more aggressively, you will reduce mileage. Oh yeah, there's one more limitation imposed by science. So K&N filter technology could be an important tool, when combined with other elements, to help keep mileage as high as possible. K&N filters are less restrictive than disposable paper or synthetic air filters and K&N Intake Systems are less restrictive than the factory installed air path. There are many variables that affect mileage such as: tire inflation, the type of fuel, weather, elevation, the speed at which you drive, the gear in which you drive, the speed with which you accelerate, engine maintenance, excessive idling, cruise control, the grade of motor oil you use, and of course, the condition of your air filter. Even the EPA fuel rating numbers for new cars are often not representative of the mileage you actually experience. It is virtually impossible to make sweeping and general claims about mileage. We certainly understand why it is theoretically possible for a consumer to experience a mileage increase after installing a K&N air filter or intake system, however, we do not go so far as to make a general claim that our air filters and intake systems will provide an increase in mileage. However, these experiences do not mean you will also experience a change in your mileage. Many K&N users report an increase in their fuel economy after beginning to use our air filters, as noted on our testimonial page. Department of Transportation suggests for improving fuel economy (see ). Replacing a dirty or clogged air filter is one of many recommendations the U.S. The theory behind this is simple, the harder an engine has to work to suck air through the intake tubes and air filter, the more gas gets wasted in the process. There is a relationship between air filter restriction and mileage. If you change your air filter with a standard, but good quality paper filter regularly, there will be no added improvement in MPG.ġ.How will a K&N filter affect my vehicle's fuel economy?