Cold air feeds (standard airbox)

[Alex]

Just thinking aloud here. I'm curious.

I still have the original airbox on my car. Somewhere I even have the snorkel and the cold air box which goes behind the headlight.

I've taken this off as it appears to be restrictive once you've ported the charger and taken the restriction out of the airbox outlet. Which is a shame as it's a really neat solution.

With no charcoal canister, I've run a cold air feed into the airbox from the inside of the wing, drawing air from behind the fog light. It's been like that for years. But it's occurred to me that it's probably not doing much once it dips inside the wing. Because there's no forward-facing duct, it's just sucking static air out of the wing (with a little airflow around the fog light).

So with this in mind, do I really need the pipe to go any further into the wing than just inside the hole for the charcoal canister?  That would still be doing the same thing, sucking air out of the  space under the headight, but if the pipe is pointing down then there's literally no airflow into it from the front of the car. Does this actually matter, as long as it's getting cold air?

Or realistically am I better either:
- putting the original snorkel and cold air box back on, as the restriction is offset by the good flow of cold air
- just leaving the airbox without a cold air feed, as it's pretty well placed anyway

[Jezza-7]

I always wonder this, as my filter is down there.

But i did look at something like this once:

https://www.merlinmotorsport.co.uk/p/naca-duct-small-naca-9-bk

mounting it just below the front bumper and cutting away some plastic so that some airflow would go into the wing area, but thought it might look a bit chavy. Its only 34mm deep and 150mm wide, so its not that big. But it might be noticeable. Only £16.

[Alex]

For now I've just dropped a short piece of hose into the wing. I figure it's at least pulling air from the right place. I know when I had the snorkel on the airbox it had quite a strong suction force through the inlet.

A bit of fag packet calculations, based on rough measurements, shows the snorkel is only restrictive going into the airbox. The inlet of the snorkel, open ends of the two inlets and outlet of the airbox and charger pipe are all about the same. The thickness of the plastic bits of the snorkel cause a restriction going into the airbox. I wonder if that's why there's a restriction on the outlet on a standard car?

From what I understand, there's no point drilling loads of holes in the bottom of the airbox if the outlet can't flow the extra air into the charger. So the only way to utilise the standard cold air feed is to ditch the snorkel, and run a piece of hose from the box behind the headlight straight to the airbox inlets.

I assume that's correct?

I'm not convinced it'd be much/any better than my current setup. 

[scully]

If you want to know how good the air is behind the wing, you should mount a pressure gauge and a temperature gauge there and go driving. If the pressure stays atmospheric, 1 bar, and the temperature is close to ambient, the place is perfect.