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K & N filters

Does anybody use them?

Some years ago I bought a K&N for my TB20. It was/is covered by an STC which turned out to be bogus in that the filter would have fitted a TB10 and would have needed modifications for the TB20.

I did not bother with it.

Supposedly there are two benefits:

  • better filtering, and
  • less loss of MP

The whole existing filter loses only about 1/3" of MP (evident by opening up the alternate air door) so it is impossible for any filter to improve on that.

The improvement in filtering would need to be tested over time using oil analysis (the silicon figure). Has anybody done this?

How do they work when soaked in water or flying in icing conditions? On the TB the filter is right at the front and very exposed.

Administrator
Shoreham EGKA, United Kingdom

K&N filters are covered with a special oil, to make them ‘water proof’.
Their filters have a higher throuput, but I doubt that this materialises in much change of your MP.

Just get a turbo to get rid of the drop. lol

United Kingdom

Somehow I think that all those claims by K&N about their “high performance” filters are nothing but marketing.

Mainz (EDFZ) & Egelsbach (EDFE), Germany

I think Michael C is removing a Brackett and installing a paper filter. He is of the opinion that he should gain some MP. If he would chime in with his experience it would be helpful.

KHTO, LHTL

I have seen a demo rig that shows clearly that the K & N is less restrictive, most of the Motorsport fraternity would agree with this but I have seen no performance changes in the two C152’s I own.

What is remarkable is the amount of rubbish that comes out of the filter during cleaning during the summer, lots of dust, grit and insects. Over winter months as you would expect the number of insects drops but all the other types of dirt drop too.

One thing is clear, not having air filtration will increase the rubbish traveling through your engine and that won’t be good.

In auto circles, K&N are known for making really good filters that maximise airflow. No idea about their aircraft filters.

EGTK Oxford

not having air filtration will increase the rubbish traveling through your engine and that won’t be good.

Maybe the difference is that the Brackett-type foam filter hides the rubbish inside it and then gets chucked away, whereas in the K&N you can see it.

I have seen a demo rig that shows clearly that the K & N is less restrictive

One could always set up such a demo, either by using a high air flow rate, or by having the MP measurement not based on zero so that small changes look really big

Administrator
Shoreham EGKA, United Kingdom

Peter

I have no doubt that the bracket filter removes a lot of dirt from the air and as it is disposable you simply don’t see the dirt, one interesting point was during the volcanic ash shutdown I was flying between Northern Ireland and the UK.

The CAA has asked piston engine operators ( who could fly ) to regularly check the filters for contamination……. I found none !

As to the demo rig , I can’t remember much about it but it did look like a good trade show demo !

K&Ns typically have low(er) pressure drop at the expense of poor filtration. Some claim you can see light through them, and through big enough holes to let particles through. There is a lot of stuff to sift through on the net. Foam filters have a long history too and filter well but compared to K&N increase the risk of fire in the event of a back fire. It doesn’t bother me in general, the risk is low.

I think paper filters are probably best overall but they’re not washable… Then again neither are Brackett foamies within the manufacturers guidance.

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