K&N Air filter systems

[ozlime240z]

We all spend allot of money on our engine and carbs so I guess it's important to keep the fuel, oil, and air clean.

I'm not convinced K&Ns keep the air clean. Until about 3 days ago I was set to buy a set for some exorbitant fee. Now I've done some research I don't think I'd put them on my car if someone gave them to me....

It would seem foam is better.

http://www.pilot-odyssey.com/~hoser/web/K%26N5.htm

http://www.pilot-odyssey.com/~hoser/web/K%26N4.htm

Some good points about surface area.

http://www.seansa4page.com/resource/airfilter.html

I like the comments in here about stopping the big stuff. Dont' we want to stop more than the big stuff?

http://www.ctracing.com/air.htm

It strikes me that K&Ns can't be all that good a "filter" because if you hold them up to a light you can see through them. Paper or Foam you can't. Also Paper and foam have a lot more surface area so air can pass through at a slower rate overall to acheive the desired flow rate.

Sure Maybe K&Ns flow better, but that's no good if they don't stop anything!

My 2 cents, but I can still be swayed.

OzLime 240z

[carguyinok]

The one thing you will never see any foam filter maker warn you about is. After awhile foam will start too come apart. If you let it get old or let oil sit on it.

Now as this foam gets old it will start too flake. These small parts of foam will then enter your motor. This is not A good thing. For foam is made of plastic. Think of what that will do inside your motor.

This is why you will never see A foam filter (alone) in any stock car. You see them on racecars because they can filter better. But they also put new foam in all the time and know when its due because they pull there air cleaners after almost every run.

If you would take A small hunk of foam and light it on fire. Watch what happens and think of that in your motor.

There is another thing to think of with foam filters. If your timeing on your Z gets out of whack you can get A back pop of fire from your carbs. That filter will catch fire real fast from this. If you dont know this happened and still are trying too start your car. Your pulling that melting plastic into your motor.

I would say if you dont like or trust K&N then go paper.

But thats just me.

[Rogersz]

I checked with a couple of off road buggie drivers , they were using large remote mounted paper filter assy's with 3 inch hoses going to fabricated air boxes over their down draft webbers. that doesn't really help much does it, I think i'll go for k &n's going with the flow i suppose.

[hmsports]

...going with the flow i suppose.

pun intended? :classic:

[morfirst]

I just installed a set of foam filters on my SU's that I salvaged from a 71 Z. I definitely like they way they improve the looks of the carburetors. I haven't been able to drive the car in a couple of weeks because the seats are at the upholsterer. I hope it will make a little bit of difference. As far as the filtering is concerned, if you normally drive the z, and regularly check the filters, I don't see this as a major issue. I certainly don't plan to race my 72 on any dirt track. Could somebody give me some insight on how to "oil" the foam filters and where to find replacements?

[AxtellZ]

Victoria British sells replacement foam filters for the Weiand/ramflow type, for around $6each. I use a light oil, just put on a rubber glove, pour some on & squish it around like the sponge that it is..pretty low-tech.

As far as the foam decomposing- yep it does. I have an old Yamaha 80cc scooter for zipping around the village- last month a chunk of foam broke loose & sucked into the carb:cry: . That shut it down very quickly!

The good news is that carb cleaner dissolved it real quick, guess i should have changed that filter in the last 7 years:stupid: :stupid: ! (The Z's get MUCH better care)

[AxtellZ]

I forgot to ask- i need the little filter to attach to the valve cover, since i pulled the original style filter.. Does anyone have a source or part #, either K&N, or otherwise?

[morfirst]

Am I wrong, or aren't the fumes from the valve cover supposed to be directed to the carburetors air intake?

[hmsports]

Racer Parts Wholesale has K&N crankcase vents - they are $13.99 and come in sizes to fit 3/8", 1/2", 5/8", 3/4" and 1" vents. Call them at 800-397-7815. They are 2" O.D., 1-1/2" High.

And yes, the fumes are supposed to go into the air filter box -- for emission control purposes.

[Zvoiture]

Wait a minute! A few posts ago someone mentioned 'foam filters' and K&N in the same sentence and insinuated they wouldn't recommend K&N because of the problems with foam filters. Are K&N filters foam on carb setups? My K&N is a big paper cone (FI). I have seen cones covered with foam but I assumed they were 'Brand X'! MAybe K&N makes more than one kind? All I know is I have a K&N and it's paper/wire mesh.

steve77

[Cuong Nguyen]

Hi all,

Regarding the comment by Mr Camouflage and the back to back dyno power runs to test air filters on a Turbo Nissan Silvia (200SX in Australia and 240SX in the US).

That show that you’re referring to is called Racescar and is shown on channel 31 in Western Australia. The results do not hold true on all cars, the reason that the Silvia lost power when using no air filter was because it is equipped with an “air flow meter”. When the dyno cooling fan is blowing huge amounts of air into the air flow meter with no filter attached, it is sending “strange” signals to the ECU, which then reacts to “save” the engine by altering engine tune parameters.

If you were to do the same with a non “air flow meter” equipped car, you’ll find the results will be different.

[morfirst]

I don't know alot about K&N filters, but the filters that I salvaged from a 71 z are round foam filters with a wire mesh retainer held on to a backplate by front spring clips. I funneled the valve cover fumes to both carburetors by installing a 1/2" plastic Tee at the end of the hose and then branched off with 3/8" hose to both carburetors. I drove my 72 z last night after reinstalling the drivers seat, and it seems that it has a "smoother" carburetor response. Plus, the foam filters opens up the engine area. I think I'll stay with the foam.