For my engine swap, looks like the various stock airboxes I've tried aren't going to fit, so I'm relegated to using a cone-style filter for the time being. Anyhow, have had K&N and Apex'i filters on cars back in the day when that was the thing to do on all "import tuner" cars. Now looking around, there are a metric buttload of cone filters on ebay and Amazon with various cheesy "tuner" names that scream "straight from China."
The funny part is, the Apexi one that I used way back when (which was expensive back then) is also pretty cheap now, making me think that all these other ones are probably pretty similar.
Since this is for a rally car, I don't want to mess around with K&N oiled filters. I'd be cleaning them every day. So dry filter it is. Is there ANY reason I shouldn't go with one of the no-name knockoffs on ebay? They certainly appear to be physically similar or identical to the Apexi ones, etc.
Note that I change filters after almost every rally event, so with stock ones that was cheap $5 on RockAuto. So I'd prefer to keep it cheap as well for this setup so I can change it. So what does the hive think?
Any reason? Filtration. You can't see that in a product photo.
All that dirt you'd be cleaning out of an oiled K&N? You don't make it go away with a dry filter. If you're serious about using a super-cheap eBay filter, I'd buy one or two and come up with a filtration test involving suction and a calibrated amount of dirt. Test them and an OE paper one of some sort and an oiled K&N, then use the one that will kill your engine the least.
If you're worried about filter longevity, get a bigger filter.
Keith Tanner said:
Any reason? Filtration. You can't see that in a product photo.
All that dirt you'd be cleaning out of an oiled K&N? You don't make it go away with a dry filter. If you're serious about using a super-cheap eBay filter, I'd buy one or two and come up with a filtration test involving suction and a calibrated amount of dirt. Test them and an OE paper one of some sort and an oiled K&N, then use the one that will kill your engine the least.
If you're worried about filter longevity, get a bigger filter.
Oh, I'm sure the oiled type catches more particles. A stock-style airbox is ideal, but not an option until I have time to do some fabrication. This is a stopgap substitute for the time being - hence why I'm looking for something cheap. This being the internet age, figured someone on youtube may have already done this test.....
Spectre filters are oiled, which doesn’t answer your question, but they’re available everywhere and fairly cheap. Quality seems to be pretty good.
the Spectre filters are what I use. I take the rubber grommet out of the base and fill it with Right Stuff to seal it up.
A spraycan of filter oil is like $8 from Summit, the K&N filter cleaner smells exactly like Spray Nine which is about $20 for a gallon jug at Home Depot. This will do a dozen or two filter cleanings. Buy two or three filters and keep them in rotation if you want convenience.
Say you have two filters ($60) and go through two cans of $8 spray oil ($16) and one $20 gallon of Spray Nine to get twenty cleanings. That's $96, or a shade under five bucks a filter. You ain't touching clamp on cone paper filters for $5 and the oiled filters actually filter better. And, that is the first twenty, unless you have an incident where the throttle cable rubs through the filter (cough) they will last much longer.
Keith Tanner said:
Any reason? Filtration. You can't see that in a product photo.
All that dirt you'd be cleaning out of an oiled K&N? You don't make it go away with a dry filter. If you're serious about using a super-cheap eBay filter, I'd buy one or two and come up with a filtration test involving suction and a calibrated amount of dirt. Test them and an OE paper one of some sort and an oiled K&N, then use the one that will kill your engine the least.
A smear of Vaseline inside the clean side of the filter housing or duct will collect enough of the dust getting past the filter to let you know if you need to step up your filtration game.
Rotaries are VERY INTOLERANT of dust in the air, so this has given me much experience in what works and what doesn't. Kind of like how Porsche got good at chassis dynamics 
Why not a Unifilter Dual? Usually retail in the 25-30 range. Pretty much defacto in dirty racing situations. Easy to clean, and I personally find the foam substrate is less likely to weep oil all the way though to the AFM or other metering sensors you might have. I'm pretty sure they contract manufacture the filter for ITG and ilk.
Search for Honda Prelude 1989ish air filter. A true OEM quality decent sized cone (more like a cylinder) filter for like 12 bucks that you can replace at any parts store. Fits on any 3" intake tube. Dont bother with the eBay crap.
In reply to maschinenbau :
Interesting! I just ordered one. Did Honda mount it in a box?
I got an AEM Dryflow with a prefilter bag, it's not cheap but it's washable and doesn't use oil, and I've never seen a hint of dust after the filter.
No idea if Honda puts it in a box, but it's pretty decently sized. I just like being able to buy one at any parts store if necessary. Denso P/N 1432041. Here it is next to a V6.
The GM EROD LS engines also come with a paper cylinder filter that could double as a tiny home if you put wheels on it. I think it's built to attach to a 4" tube. I doubt it's going to be $12.
