Are car air filters really necessary?

Question

A friend of mine has been running his 350Z with no air filter since it was new. It has over 70,000 miles on it and still runs great.

Answer 1

Internally the motor will have damage to it. None filtered air has small dirt particles that will scratch cylinder walls and reduce cylinder compression and or increase oil consumption.
A low restrictive air filter is the best way to go like a K&N or similar.

Answer 2

If auto manufactures thought for one minute air filters were not necessary they wouldn't have been installing them as an OEM part since the first motor car ever hit the road.
Of course they're necessary. Fine dust and dirt particles clear down to the 25 micron size will eventually abrade piston rings and cylinder walls. Proper compression seal will be lost waisting fuel and motor oil. Air filters also keep throttle bodies and carburetors clean. If a minute dirt particle loges in a tiny feel injector or carburetor air bleed, power valve, accelerator pump nozzle or jet things go south fast.
I'm sure other answers to your question will convince you that your "buddy" doesn't give a hoot or understand motor maintenance.

If every race car series in the world didn't think air filtration was necessary why do they use some type of air filtration?

Answer 3

Let me ask you this: Have you seen the air filter housing on your friend's car? Do you know with absolute certainty that your friend has been running no air filter for every single one of th 70,000 miles? I will tell you that I seriously doubt that anyone can drive a car for 70,000 miles without an air filter without suffering ill effects within the engine, even if it "appears" to run great. Very few internal combustion engines operate without some kind of air filter. And very few people will tell you that it is not needed. The ones that do are ignoring over 100 years of internal combustion engineering development and real-world data that unquestionably blows their "let's see if we can run this motor without an air filter and see no ill effects" idea well off the road and deep into the weeds.