Air filter - when to replace?

[ArthurH 7]

Just wondering if there was any good advice out there about when to change an air filter element.  My son is running a K&N element in a (mandated) standard housing in his race 1.6 8v.  The filter is a little discolored, but has probably only done a few hundred miles from new.  As he is on a tight budget, he understandably doesn't want to waste money changing anything unnecessarily, but also can't afford to give away any BHP.

 

Any thoughts?  Advice?

[Tom Fenton 1,542]

Buy the cleaning kit!!! Job sorted.

[ArthurH 7]

Turns out there's a cleaning kit ! Who knew....?  Thanks Tom.

[jackherer 543]

K&N sell a device that tells you when the filter becomes restrictive and needs cleaning, they're not cheap though - https://www.ebay.co.uk/itm/381956189037

 

But you can get exactly the same thing without the K&N logo for much less - https://www.ebay.co.uk/itm/223307984145

[Tom Fenton 1,542]

As it’s a race car clean it every meeting. I’d also consider not oiling it after you’ve cleaned it. Every little helps!

[ArthurH 7]

As they say; 'great minds think alike' .  I was worrying about how much the self applied oil would reduce the flow.  I'm guessing that a cleaned filter would never flow quite as well as a brand new one, but it would be quite acceptable for a road car.

[xstian 12]

Even a new filter should be oiled, that's what catches the dirt. Surly, if you don't oil it you may as well not bother having it or just use a thin mesh. 

[Tom Fenton 1,542]

Yes the filter "should" be oiled, but in a closely fought race series, what is more important to you, possible slight power advantage, or ensuring good filtration for an engine that may only do a season or 2? So like I say, if it was me, I wouldn't oil it. I'm assuming the regs say that a filter of some sort must be in place in the standard air box.

[ArthurH 7]

Your assumption about the regs is correct Tom.  And yes, the greatest risk to the engine is probably sand/dust from a gravel trap 'incident'.

11 hours ago, jackherer said:

K&N sell a device that tells you when the filter becomes restrictive and needs cleaning, they're not cheap though - https://www.ebay.co.uk/itm/381956189037

 

But you can get exactly the same thing without the K&N logo for much less - https://www.ebay.co.uk/itm/223307984145

That is quite some mark up for obviously the same item!  Thanks Kieran.

[welshpug 1,661]

original fit filter was an oiled foam item much like pipercross used to be