Does the K & N Air Filter have a positive effect on MPG? How much? Is it worth purchasing if it has no effect?
Is that your experiance, southerncannuck? I've seen the increased power, but I've also seen a slight (~2)mpg boost since putting mine in almost a year ago. One would think the engine having to do less work to draw in air would allow for some minor improvement?
At partial throttle, the throttle body is (the main) a restriction to airflow. Unless the throttle plate is nearly fully open the restrictive contribution of the filter won't come into play. This is why the pulse and glide tecnique improve mileage so well. The pulse is full throttle, with the least intake resistance posible, and the glide is, well, a glide. Louis
It's beyond just the filter, but a smooth pipe with a cone filter at the end will reduce flow reduction at or near WOT. K&N and others make warm air induction kits that terminate in the engine compartment. Drawing in warmer air will absolutely help fuel economy. I have an AEM system that I made work with my Ecotec Sunfire after taking it from my older 2.4l Sunfire. The cone filter at the end looks just like a K&N filter. So, the filter itself won't do much, but as part of a WAI system, it can help.
As a side note more flow always goes hand in hand with less filtration ability, no matter the maker of the filter. K&N power increases would be more evident at the highest RPM range. Anything below that point the throttle plate is more of a restriction than the filter ever would be. I think you would see the same mpgs using a paper filter with a WAI setup.
Hi, 2 parts to this K&N filter conversation. Part 1: The filter: K&N says it filters 1 -2 micron size particles from the air, and that level of filtration has to help keep all the internals cleaner and more friction free. Add that to less restricted air flow, and K&N's technology seems to be at the top of the air filtration game. PLUS, K&N filters are CLEANABLE and RECHARGABLE coton based filters, not paper. The initial cost is maybe 4 - 8 times a paper filter [a K&N for my 08 'Riot Sport 4x4 cost me $44] but has a limited warranty for 1,000,000 miles; that's right, kiddies, 6 zeros! The multiple use recharge kit [about $10] is to clean the element and replace the filtering oil about as often as we would change a paper filter. One would have to put 100,000 miles per year on a vehicle for ten years to get to the end of the warranty. For me, less gas guzzling trips to the Parts Store, plus about 20 less filters over ten years of driving makes this a no brainer. Add to all the above, as hypermilers, many of us are interested in reducing our CO2 output, and manufacturing, packageing, shipping, and disposing of 20 paper/metal/rubber air filters over ten years really ratchets up the CO2 account. Part 2: MPG: While K&N makes no specific claim for increased FE as they do for increased HP, they do acknowledge that increased air flow should improve FE, all other factors being equal, ie, tire pressure, driving habits, etc. The main point is that a dirty filter can reduce FE as much as 10%, ergo, a super efficient filter probably will effect FE positively. Personally, I have opted for the K&N air filter, as well as a K&N oil filter with my choice of Castrol Syntec 5W-20 for my Jeep 'Riot Sport. Happy Hypermiling!
I don't doubt that a dirty filter might block airflow by as much as 10%. I do doubt that it matters. Even if the dirty filter blocks 50%... It might make a difference at WOT and high rpm, but lower, where we drive? No. At 1/2 throttle and 2,000 rpm, I'm drawing in 1/6 as much air as at WOT and 6,000 rpm redline. A 50% restriction there still leaves a 200% excess flow capacity. My paper filters last several years with MUCH less than 50% blockage. The Honda Insight (1st gen) has the most restrictive intake of any production car. It snakes all over the place, and it's skinny tubing the whole way. How does that work for one of the most fuel-efficient mass-produced car ever? It shows me that it's not a problem.
...with the same filter surface area. Increasing the filter surface area even using the same filter material would result in higher airflow WITHOUT a hit to filtration ability, no?
I would think so. That's why we have 8x8 inch filters (on my car, at least) and not tiny 2 inch round ones.
K&N filters have been known to cause the MAF sensor to gum up/get dirty which can cause a loss in FE. and CEL's. When you clean one, and then re-oil it, you should stuff it with newspaper for a while to allow excess oil to be removed from the filter, then re-installl. To clean the MAF, get some CRC MAF cleaner and DO NOT TOUCH the MAF wires in any way or you'll be buying a new one. A K&N filter will improve throttle response and give a slight increase in FE, but their HP gains are difficult to ascertain as each car is different and those HP gains are based on dyno runs, not the real world driving we all endure (no wind resistance).
I have a filter that has properties of both a K& N and paper...it is reusable, but the filtration is exceptional to say the least.
I don't know what the thread moving protocols are, but can I get this moved to the "For Sale/Wanted" in the "Our Community" section. Thanks
