Automotive engine air filter - Foam

[jeremysoca]

Hi there folks.

I had a question regarding automotive foam engine air filters. I was wondering if anyone here had any practical experience
working with foam air filters. My question is what PPI (pores per inch) would be most effective at both filtration and flow. Im thinking a 2 stage filter. I understand the more you flow the less you filter and vise versa but there has to be a sweet spot.

Thanks for any information you may offer.

Jeremy

 

[patprimmer]

Surface area also comes into the equation.

Regards
Pat
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[Tmoose]

i think the oil coating does a lot of the "filtering".
Industrial engines in commercial and high end lawn care and offroad equipment sometimes use an oiled coarse foam prefilter with a paper air filter behind. the one on our mower keeps the intake tract nice and clean. I can not say the same for the big name oiled cloth filter i tried on my old dirt bike. That experience was similar to a few bike tuners on various internet bulletin boards. I now use a Wix paper filter for some 80s GM passenger car, but don't ride very much either.

 

[jeremysoca]

Thanks moose

 

[BrianGar]

Careful with oiled foam and Maf sensors...

Brian,

 

[jeremysoca]

I am aware of the over oiled filter issue. Problem is, without the oil the filtering efficiency is diminished. Over-oiling can cause MAF issues. It is a fine line.

 

[MiketheEngineer]

Check with mfg. We used to wring them out with raw gasoline and re-use. Always seemed to work OK

 

[drwebb]

Specific Foam Air Filter Oils usually contain tackfier that improve adhesion of dust particles as well as to the open cell foam support (maybe helping MAF compatibility, although gauze air filter oils more popular for automotive apps aren't usually as tacky as foam). They also often contain a dye to aid estimating distribution visually, which typically more economical, tacky Bar & Chain oils don't. FWIW.