Installing engine air filter... which way is up?

orrd · 12-20-2011, 02:29 PM

I'm replacing the engine air filter in my '01 Insight and I suspect the old one may have been installed upside down. Apparently it fits in there either way. Can someone tell me which way the engine air filter is suppose to go in?

(It's a K&N filter and it looks a little different from the factory one, so this might only make sense if you have a K&N filter.)

So which way...

Bigger part on top like this?

Code:

  ############################
    ########################

Or bigger part down like this?

Code:

    ########################
  ############################

I've been searching everywhere online for photos or videos but couldn't find any.

madmanmostafa · 12-23-2011, 03:38 AM

I think it goes ribby side down. When you have it upside down, it doesn't fit quite flush and ends up not creating the proper seal. So it would be like your first image.

Cobb · 12-23-2011, 12:53 PM

It should only go in one way. With the newer insight the top side is flat, the bottom side has the pleats.

Sent from my Autoguide iPod touch app

Varak · 12-23-2011, 04:09 PM

Most air filters should have an arrow somewhere on the frame that points in the direction of air flow.

orrd · 12-27-2011, 12:56 PM

It really does basically fit in there either way, but I'm sure one way must seal better and work better, I'm just not sure which.

So I guess at least one person says the smaller half goes down, so I could try that. It doesn't seem to have any arrows to indicate the airflow direction, but there is a logo and some numbers on the side of it... which would be upside down if I put it in that way. But maybe that's still the correct way?

**AClewell** · 12-27-2011, 01:04 PM

The ribbed did should face the dirty air. That gives it more surface area to filter incoming dirt particles.

orrd · 12-30-2011, 07:09 PM

Quote:

Originally Posted by AClewell

The ribbed did should face the dirty air. That gives it more surface area to filter incoming dirt particles.

Both sides are the same as far as the filter material... it's all just pleated (folded) so both top and bottom have the same amount of surface area. So the only difference between which side is up is how it fits in the filter box, and it's not really obvious to me which way it fits better once you close it up.

Cobb · 12-30-2011, 08:00 PM

Well..... If its a tight fit either way, then go for it. The i2 has a tab that is offset, so it will only fit in one position one way up. Can you post a photo for us?

Sent from my Autoguide iPod touch app

orrd · 01-03-2012, 06:33 PM

I contacted K&N and they said "For your particular filter, you want the flat side up or facing the engine if that makes sense.".

So I think that's a consensus since at least one other person said the same thing, the proper way is with the flat side up (like my first illustration).

Cobb · 01-03-2012, 06:45 PM

Interesting.... I don't think you can go wrong either way as long as there is a good seal. Ive heard a lot of bad news about kn as some say the oil film can foul and cause map sensors to read incorrectly. Others say it doesn't stop as many particles that a paper filter does. Surprise, surprise, many newer filters are cloth vs paper anyways.

Ive used they for years with no problems and my supercharged tacoma loved them. Amazing how fast it would go from red to black after a few thousand miles running 15psi of boost.