Good info, thanks a lot

 

Philip, any feedback on performance of OEM and replacement brands from your project? Which paper version was best?

 

The oem filter actually did very well. I tested almost 20 brands and it was right in the middle of the range and obviously does a nice job with filtration. Many of these were weird brands I found online, but of the aftermarket replacements you can find in a local parts store Purolator's Pure One filter did a little better as did Napa's Proselect. Fram's Thoughguard filter also did well. The increase in flow over the oem filter was tiny though. I was actually surprised by the results of the project because I was expecting there to be more of a range on how these things performed. The difference between the K&N and the worst one was only a few percent. I am sticking with the oem filter in my car, but I wouldn't see anything wrong with switching to a decent aftermarket filter if its in the same price range.

 

After I bought a couple K&N drop in air filters for my 2010 G37, I decided to go online and find out if these would really make a difference in HP and fuel economy. After reading what many experts with a lot of good test equipment had to say, I sold the K&N filters and went back to the OEM. Basically, there is absolutely no advantage in fuel economy with the K&N filters. The MAS and computer determine how much fuel to feed the engine based on how much air is entering. You can plug your filters with 5 pounds of dirt and your fuel economy will not decrease one bit; your HP will suffer dramatically because much less air will be allowed into the engine. The K&N filters probably allow a little more air through at full throttle, but the downside is, the air is not filtered as well as the OEM filter. I also read where a guy over oiled his K&N which eventually ruined the MAS. Another guy purposly plugged the air intake on his BMW to see if it would effect fuel economy, and he discovered that the MPG stayed exactly the same, but his HP was greatly reduced. In the days of carbureters, dirty air filters effected mileage, not today. Sorry K&N, I don't need an extra 1 HP, or the added expense of purchasing ($120) or the hassle of cleaning and re-oiling---I'll stay with OEM.

 

K&N filters are handy if you happen to have a volcano erupt in your area. The paper filters will clog up immediately, from the dust, while the K&N"s can be constantly cleaned.
I don't think I will have to worry about that in SW Florida, so I use the regular paper filters.
Tom