Stupid cone air filters!

Am I the only one who is annoyed by the stupid cone air filters that every custom car builder seems to just slap on the air intake these days? They spend months and tens of thousands of dollars building a custom car and then just slap a stupid pink cone filter on the end of a tube! I watched car show this morning that put twin turbos on a Lamborghini and sure enough, stupid pink cone filters!

Why spend so much time an money on a car and then punt on the last 0.5% of designing a proper intake system and proper air filter?

But hey man, they sound cool! And the manufacturer said they'd add ______ power! :lol:

Yeah, I see customer cars with them installed. They're almost always disgusting. Packed with dirt, bugs and all kinds of other crap. Sure, they're cleanable, but that doesn't mean they get cleaned.

Ivan (motoYam82) has just posted a video on his channel on this and of course Paul did an excellent video of problems on a Chevy van with damaged stock airfilter housing causing a lean condition.

The main cause of the problem in both videos appears to be changes to the inlet altered the velocity characteristics of the flow at the MAF sensor. Normally at low air flow rates in a large duct or pipe the air is much faster in the centre of the duct, the very fine mesh screen before a MAF sensor is intended to make the air speed (velocity) more even across the whole bore of the duct.


Without a screen the MAF sensor is reading a point on a velocity profile similar to (1) but was calibrated for a velocity profile similar to (2).


What worked for a speed-density MAP injection system just won't wash on a MAF based system.
MAP system are very tolerant of changes to the engine or intake but MAF's are sensitive beasts.

The other problem with K&N style oil wetted air filters is contamination of the sensor.
When MG-Rover introduced the BMW diesel engined Rover 75 after a year or so it became apparent that the MAF sensors were failing prematurely due to dirt contamination but the problem wasn't found in same design sensor used in BMW and Land-Rover models. The cause was the postion of the air filter air intake which was positioned to draw cold air directly from the front of the vehicle and was exposed to road spray. They cured the problem by simply fitting an aluminium plate to shield the intake from direct road spray.

Back when K&N filters first hit the market engines ran carbs and there was little or no choice of air cleaners to fit modified engines. Often you would see a modified 4 cylinder engine running on a hot cam with a pair of Weber DCOE's with ram tubes and no air filters (to this I must plead guilty !) While these engines sounded and looked great just adding any air filter to contain the stand off back spray at the mouth of the carbs would often added a few horse power.
In those days stock carb engines particularly from the late 1960's early 1970s when air fuel ratios were made leaner to reduce emmisions were generally used the exhaust manifold to pre-heat the intake air and were very sensitive to air intake temperature. Any fault or modification to the air filter inlet on these engines to the inlet could cause a lean condition.

Ivan (motoYam82) has just posted a video on his channel on this

Yep! Saw it too... I'll post it for everyone who's interested: