Air Filters - HKS or K&N? And what needs oiling?!

[Hopkins]

I am thinking about buying either the HKS or K&N performance air filter. One obvious difference between the two is that the K&N filter requires oiling (albeit fairly infrequently). I don't really understand where the oil would go or what it does!

Can anyone enlighten me, and perhaps offer some general advice? Improving the flow through the air filter (while not compromising the quality of filtration) seems like a fairly sensible thing to do. Are there any others worth considering?

[PeteH]

Erm Mazda... Seriously, it will probably flow as much as the aftermarket stuff, and filter better.

The K&N oil is a very light dusting of oil on the 'sponge'. It is there to trap the smaller bits of dust that would otherwise work their way through the sponge. It is required because the K&N design has larger 'holes' in it than paper elements, so its dry filtration properties are worse. The oil doesn't 'go' anywhere (in theory), because it is such a small dusting of oil. In reality some oil inevitably gets drawn through the filter, and will be deposited onto your MAF sensor. How much, and whether this is a problem, depends on how much oil you use, and how often.

I use a K&N, in my REVi, and I used the minimum possible amount of oil. But #racecar.

[V8 Power]

K&N filters are supplied pre oiled so you haven’t got to worry about cleaning and re oiling for some time.
The HKS hybrid panel filter looks good with its bright green filter medium, don’t know how good they are though? One thing is that they do not have a perimeter rubber seal so rely on plastic to plastic contact which does not seem very good.
I personally use Cosworth panel filters. Because the Cosworth name and they use a dry synthetic filter medium which seems to do the job well and the Cosworth name
However as Pete said none of them are probably any better than the standard paper filter.

[Honkytonk]

I went with a Mann paper filter when I did mine last, as it works and the car was designed with paper filters in mind. I think general consensus is as long as you buy 'proper' paper ones from a reliable source, you're not risking some kind of filter disintegration and intake. I do now have a K&N filter I picked up, so I will switch that over when I next change, but tbh it's down to personal preference as long as you're buying a decent one and not over-oiling it so it's coating the MAF. I don't really think there's as much of a difference between 'street' filters as advertising people may like you to think, as the MAF sensor is there to calculate whatever air/fuel ratio is given to the engine. I would be very surprised if the same car on different (legitimate) filters makes a difference in the average case.

InB4 Warpcoil links it, but similar has been discussed recently.

[Hopkins]

Ah, I see, it is there to make it sticky! Presumably, to oil it one must use some sort of mister to attempt to deposit as fine a layer of oil as possible?

Interesting to read about potential fakes via the link.

[PaulAV]

Normally you purchase a kit (k&n do thier own fire about £20) this contains cleaner and oil in spray form, you an get at least 2 or 3 cleans from the kit and more oils (so you'll need to clean it with a detergent like washing up liquid)

[AndyBrad]

Ive got a pic with the mazda one, hks and cosworth one out of my car. The mazda one is the best fitment wise. the cosworth a very close second (what im currently running) i binned the hks as it was very poor imo.

[GreySilver Beast]

I know my GT86 is completely different from your RX-8, but for the past 6yrs have had a Pipercross Air Filter under the Bonnet and had no issues from this being fitted to the car

[Hopkins]

Thanks for all the info!

[acegeezer]

Stick with Mazda, for fitment and performance there is absolutely no need to swap it.. cheap enough too
My question is .. why do you want to change what is already a perfectly fine filter?

[Hopkins]

Stick with Mazda, for fitment and performance there is absolutely no need to swap it.. cheap enough too
My question is .. why do you want to change what is already a perfectly fine filter?

I have to admit, it was this Engineering Explained video:



In it, he notes a measurable difference in his test case. Admittedly, this is not to say that there would be a difference on the RX-8. And I concede that, even if there were, it may not be immediately noticeable. However, since I care about my car I am interested in small, incremental improvements. That said, I am entirely open to arguments as to why I shouldn't!

[acegeezer]

I ran my R3 for just short of 6 years with the oem filter and she was faultless, that's all I can add

[350matt]

I think the RX 8 intake system is one of the best I've ever seen for an OEM road car
the air filter area is large and its all well flow optimised so there's little to be had by replacing the filter element with something more free flowing as the air flow capacity is already large
that said I run a Cosworth air filter on mine

[V8 Power]

Even though I know there is little or no improvement to the standard paper element it is something I have always done on every car I have owned going back to my teens. (Long, long time) I always put a so called performance filter in/on.