K&N panel filters worth buying or not

[ben g]

I have a simota filter on mine and apart from the noise, there isn't much difference, if any, in power.

Same would most likely apply to a k&n panel filter. No real point.

The paper filters are cheap and very simple to replace. You could change it every 6 months if you wished and after a few years, it'd cost the same as one k&n panel filter.

 

[Lee Young]

I was watching Top Gear this morning and the monster engine in the Rolls used in the next Jonny English film, had 2 cone K&N filters. Looked good and imagine they must have been compared to OEM and many others. Seems to make sense to me that more air going in means some gain in power. Moreover, you only have to buy it once.

 

[Ewazix]

I was watching Top Gear this morning and the monster engine in the Rolls used in the next Jonny English film, had 2 cone K&N filters. Looked good and imagine they must have been compared to OEM and many others. Seems to make sense to me that more air going in means some gain in power. Moreover, you only have to buy it once.

Ideal for Jonny English and the principle of more air (denser if possible) in = more potential power is right...... but as said before by several contributors on a stock set-up and engine that is ecu controlled it can't and won't use the extra air, what it actually does if it's excessively more than it expected is retard things to prevent over-lean running and reduce power! There are plenty of disappointed user write-ups with dyno figures to back this up. Old tech non-ecu engines give a few bhp extra with a trumpet or K&N and re-jetted carbs but it won't work on a modern unmodified ecu engine/map.

Stock air boxes have about 20% excess air capacity above max running volumes to account for filter deterioration and atmospherics so there is no restriction preventing more power being developed on a stock engine/map. The BMW intake system is one of the most advanced out there and sets up pulses and swirl to harmonise with the cylinders which actually require a degree of restriction, removing the intake system for totally free flow will reduce, not improve power. If a simple (and cheap to make) free-flow power cone trumpet or dry-oiled pancakes worked better BMW wouldn't invest millions on RD intake technologies. A cold air system and re-map is probably the only worthwhile intake mod on the Z4 but I haven't see any dyno numbers.

As has been mentioned many times there is actually very little if anything to be squeezed out of these engines without radical mod's, forget Jonny English, you need to call Jonny Essex! :wink: