AlexGJ248

A Cosworth air filter has been purchased

MB

You seem quite sure, so I have to ask how you know for a fact there is no power gain? Also what does 'tranparent' to 300 bhp mean and how do you know it's this exact figure.

Genuinely interested.

richmc

Oh yes it does!, but it's the pollen filter for the cabin air, sits under the plastic panel neaxt to the wipers, usually full of sh1te.

s2k4tony

FWIW I think you get more gains from FI, even that is perhaps 5-10bhp for a car giving out say, 250hp (like an S3 perhaps). I've always guessed that with our car, the increase is less than 5hp. So barely noticeable for fast road use.
Good shout on the pads, I need some Ferrodo's for mine at some point.

tailhappy

By transparent I mean the stock air filter does not restrict the air flow required by the engine in stock tune. The 300 bhp is an approximate (the figure is probably higher). On my last car (MR2 rev 3 turbo) the stock OEM filter did not cause any restriction until above 350 bhp. This was a "panel" type filter. As you say the S2K has a fancier tapered cone filter. But for the sake of the non believers on here lets say 300 bhp. So the point is you gain no more power.

s2k4tony

That would make sense... you would need to re-tune the ECU to tell it that more air is coming in with a free flowing filter, thus telling the ECU "more fuel please".. I'm no expert on that kinda thing, but without the ECU fettle, you may as well swim your arms out the windows to go faster if you "uprate" your air filter. Even if you did, whats the expected bhp increase in reality... 3-5hp?

MB

It sounds like the video link in my signature

Tony, not quite correct on the mapping. The standard ECU can compensate for the reduced resistance / higher airflow through a different filter. Essentially though, the fuelling gets leaned out by a fraction, which is where extra power comes from. Where it cant cope is with full intake and exahust mods, as the engine loses all backpressure intake and exit, and that's when you get a fair bit more power, as the ECU runs out of room to compensate. It's leaning the mixture out. Alas this isn't healthy for the engigne in an extreme case, as combustion temps go up.

Tailhappy, I will accept that adding a different cone filter to a standard S2000 airbox will yield little difference. A different intake can and will add power though, if chosen correctly. It's purely based on DP over the cone. Small numbers in isolation, but combined with other breathing mods it can be worth it.

MIP

The other good thing about filters that people don't seem to think about is filtration. OEM filters do tend to stop alot of crap going through your engine, I don't know how other brands perform, I've read that K&N arn't great (servicable filters are a waste of time if you ask me). Google it.

MB

K&N are very good at filtering... what bugs me is that most aftermarket filters don't actually tell you the micron level of filtration. But as a rule, for the same size surface area, if you get better flow the DP is lower, and it's therefore likely to not be filtering as well. Which isn't a big deal imo. We are talking about microns.

tailhappy

So true. I've also been told by specialists they've seen the foam ones break down over the years and the engine literally start to ingest them