Air Filter Testing Study

About what I expected.....

 

Me too. Those results pretty much mirror a similar test done about 30 years ago.

Parts originally designed for racing use often do NOT perform well "on the street".
The objectives are different........or should be.

 

I could not correlate the colours to the bars, so cobbled this. Still not sure I've got it right; please comment if anything looks awry:



Addendum:

1. I see now, that the order of list at the right of the graph correlates with the bar graph: descending order of the list corresponds to left-to-right of the bars. Still, a little easier to read as I've edited.

2. I was thinking higher bars was better, ie: the right end bar was the best. See the opposite is true lol: the height of the bar represents the percent of particulate passed. Higher is worse, and the left end is the most restrictive. Maybe it might also reduce flow too much??

I'll stick with the Toyota filter. If I ever get around to changing it...

 

It isn't just the amount of "dirt" passed but the size of the particles. An air filter is supposed to filter and so will always be a compromise between air flow and filtration. One reason why air filters are frequently much larger than the actual air intake to the engine.

 

There is a reason why the manufactures go with a paper filter over an oiled filter. A guy did a similar study at least a decade ago over on Bobistheoilguy web site. He just dropped different filters in his car and set up a clean filter down stream of the test filter to pick up any thing that got through the test air filter. He drove several thousand miles and changed out the filters as well as the down stream catch all filter. It wasn't as scientific but he got similar results. It went by just by how dirty the down stream filter was.

I used a K&N back in the 90's and lost a Turbo over it. I probably drove with a K&N for maybe 50K-60K before my turbo seized. The inlet was filthy covered in an oily grime. Replaced the turbo went right back to a factory paper filter. Just for S&Giggles I pulled the inlet hose on the Turbo the day I sold the car. I had 128K on that replacement Turbo with a paper filter and inlet side of the compressor looked brand new.

 

OK ... So I'm not sayin' ... I'm just sayin'.
The "free" air and cabin filters I got from Toyota in OEM Toyota boxes ... are the flimsiest filters I've ever seen. The $6.50 cabin filter on sale at Advance looks physically hand-over-fist higher quality from the get-go.

 

The filtration graph is great and all, but I think a more useful measure is a fraction of particles passed compared to the flow rate of the filter not at steady state (since the author notes that the differences in flow rate at steady state are effectively negligible).

I'm particularly interested in what the delta-P (pressure difference) is when the vacuum is varied (like you would expect under WOT in a turbo application). You would expect that a better flowing filter would yield more immediate engine response and quicker spool rate.