So I've found lots of info regarding hp claims of all the usual air filter options. There is very little filtration info however! The perrin cai looks sweet but the oiled filter works just like the oiled filter in my dirt bike. They even specify the same filter oil! I don't live anywhere near nice clean streets (Montana). So I want to be sure I'm not letting lots of abrasive crap into my turbo. Opinions? Facts?

 

If you are that worried about filtration and live in a dusty area, then sick with the stock filter. Nothing aftermarket is going to filter as well. It's more about keeping that dust out of the motor that wears bearings and cylinder walls then worrying about stuff passing through the turbo. Not that turbos are a dime a dozen, but turbos are easier to replace than main bearings on the crank.
My $.02; I'd rather be down 10 hp for 5 years, then be up 10 hp and a motor rebuild in 5 months.

 

Also, not sure what all you have done to you evo, but the stock intake in teh Evo is quite decent. Its not as restrictive as you would expect from a factory airbox/filter. I have seen cars easily tuned to about 400hp (at the crank) with stock intake still holding its own. Is it ideal? No, but its not as bad as one would expect.

Going to a full turbo back 3" exhaust is far more beneficial as that is where most of the restriction is in a stock Evo's air handling.

 

Good advice. I'm mostly worried about dust taking the blue off the bbk compressor wheel. j/k. I think the rings or valve seats would be the first to go from ingesting abrasives. I was hoping someone would quantify the filter mediums, ie in microns.

 

You raise a good point about lack of technical specs on filter performance...

Though I have to wonder how much of an issue is it really? I mean there has got to be some point at which the particles ingested are too small to cause any significant damage? I haven't heard of any Evos failing due to dust ingestion through filters. And we know how many evos are thrashed and rally raced and abused in dirt and sand and all that. I think that for the most part, just about any decent aftermarket filter will do a good enough job for the average Evo duty cycle. I don't see dust ingestion being a serious problem (somethign that could cause damage!) unless you maybe rallycross the car on dry dirt/sand a lot?

If you are scared, stick with the stock filter. If you are just daily driving the car around unless you spend all your time on dusty gravel roads, you are probably ok with going with a decent aftermarket filter, so long as you keep an eye on it and clean it frequently, and once in a while take a peek into the turbo and makes sure the leading edges of the compressor dont look "sandblasted".

 

I'm still leaning toward the Perrin. I think the best way to spot a problem is with oil analysis, silica content is always measured. I'm just trying to be a little proactive (admittedly ****).

 

I got the hks open filter ( sponge one ) ... and i hate it !!!

 

agreed, although i would suspect with oil changes being as frequent as they are in the evo dust damage in the oil will be less of an issue in the worst case situations than turbo damage? I dunno just speculating.

Perrin makes good stuff!

Sadly I have continually heard bad things about the HKS sponge filters... so yea... I think those are really meant to be a minimum filtration for a dedicated tarmac track car. Meant to minimize intake restriction, not really be a exceptional filter lol!