K&N Air Cleaners

[Sean O'Donnell]

My car is running Webers and has K&N air cleaners. I was thinking about swapping them to Knecht air cleaners. I was hoping to get some opinions. I included a pic of the current setup.

[Mike Wilson]

There are adapter plates available to use the Knecht mesh air filters.

Mike

[Phil Planck]

Available from Precision Matters

[Mike Wilson]

Correct, Phil, and I believe a different configuration for the jet stack.

Mike

[Sean O'Donnell]

Thanks guys. I was talking more about fire risk and if swapping would be worth it?

[Brian R Adams]

Thanks guys. I was talking more about fire risk and if swapping would be worth it.

Yes swapping would be worth it. K&Ns are a real fire hazard on the 356. And they don't filter better than OEM types. And they don't improve breathing or induce more power.
-

[C J Murray]

Thanks guys. I was talking more about fire risk and if swapping would be worth it.

Yes swapping would be worth it. K&Ns are a real fire hazard on the 356. And they don't filter better than OEM types. And they don't improve breathing or induce more power.
-

Once again, I disagree. K&N or similar filters are not a fire hazard. Excessively rich jetting is a fire hazard. Cloth and paper filters only burn when they are saturated with fuel and that only happens if you have large amounts of fuel mist standoff which condenses on the inside of the filter assembly. Proof: there are about a zillion cars and motorcycles using K&N air filters and they aren't all sitting on the side of the road burning. I have used them on many vehicles and sold many for motorcycles.

If your jetting is crazy rich and your engine backfires regularly you are at risk of a fire. Lift the top off your K&Ns and look for wetness where the filter rests. That is dangerous. The Solex Knecht filters won't burn but they don't filter either and they stain when the jetting is overly rich.

[Brian R Adams]

If your jetting is crazy rich and your engine backfires regularly you are at risk of a fire.

That may be a true. But, my Weber jetting was not rich at all, and the engine never backfired. I started running out of gas storming up a long hill, and switched immediately to reserve fuel pickup. While it was taking up the renewed fuel flow the engine bucked a bit and coughed softly, one time. Then the bowls filled and I was again under power. However the engine soon started losing power, running rough, and smoke trailed the car.

Is a K&N fire proof of crazy rich mixture? Must my engine have been backfiring regularly but I somehow never noticed?
-

[C J Murray]

Was it too rich? Yes. Then it only took the no fuel backfire to ignite the gas soaked filter. If you try to light an oiled k&n it will not be easy.

[C J Murray]

If my car catches fire tomorrow I am going to be really upset!

[Sean O'Donnell]

Thanks everyone. CJ, hopefully we didn't jinx you

[Juha Vane]

My 356 has Weber 40IDF carbs and K&N filters. They are quite old and I was thinking to replace them.
Would there be some old fashion oval paper filters suitable to replace the K&N filter units?

I recommend to check this youtube where Best Rest motorcycle stuff supplier tested the various air filter
types. Not a 100% scientific test, but give you an idea about various filters and their filtering capacity.

https://www.youtube.com/watch?v=JgZPkggKNiI

Don't pull the tar & feathers out, but as I'm getting older, I've been thinking more critically also about stuff
that is targeted to car aficionados. I believed the advertisement and one of the first things I did to my
'85 911 was to change the air filter to K&N. Why, because I believed the ad that it's better than the original.
I really don't think so anymore. In a Calvin and Hobbes comic strip, Calvin state something like this "3 minutes
ago, I did not know that I can not live without this product". Successful marketing.

[Harlan Halsey]

Thanks guys. I was talking more about fire risk and if swapping would be worth it.

Yes swapping would be worth it. K&Ns are a real fire hazard on the 356. And they don't filter better than OEM types. And they don't improve breathing or induce more power.
-

Once again, I disagree. K&N or similar filters are not a fire hazard. Excessively rich jetting is a fire hazard. Cloth and paper filters only burn when they are saturated with fuel and that only happens if you have large amounts of fuel mist standoff which condenses on the inside of the filter assembly. Proof: there are about a zillion cars and motorcycles using K&N air filters and they aren't all sitting on the side of the road burning. I have used them on many vehicles and sold many for motorcycles.

If your jetting is crazy rich and your engine backfires regularly you are at risk of a fire. Lift the top off your K&Ns and look for wetness where the filter rests. That is dangerous. The Solex Knecht filters won't burn but they don't filter either and they stain when the jetting is overly rich.

+1 I've had K &N s on my SC for about 30 years. Because they filter much better than the original rock sifters.

[Juha Vane]

Agree, the original Porsche filters are very coarse, but my K&N start to be
worn out and need to be replaced with something.
I have >10miles gravel road before getting on tarmac, need good fiters.

[C J Murray]

There is nothing wrong with paper air filters when there is one for the application. They filter smaller particles and you just replace them on schedule or when obviously dirty. I only use K&Ns for applications where there is no original paper filter available or for high performance or for racing. Dyno testing proves that K&Ns make as much power as having no filters. I think modern vehicles have well designed non-restrictive paper filters but years ago, maybe now, dyno tests showed that some were too restrictive. I cleaned the K&Ns on the race car this week after little use and the amount of dirt going down the drain was considerable. I'm glad that didn't go through my engine.

Juha, if your filters are genuine K&N the elements will have a part number molded into the rubber seal area and you can buy the elements separately.