I was having a look at the air intake and took the outer case off and wondered what the flap is for (as shown in picture below)?

The cold air going under the flap just goes out the back of the case into the engine bay and is not directed into the pipe going into the air box. Presumeably there is a reason for this flap? Is it to prevent water going in? What happens if you remove it (other than more air going into the air box)?

Water deflector.

The opening is still the same size so you wont get more air in, maybe slightly less turbulance but thats it.

Hi Jonno,

I think it is an interesting and very clever piece of design that means the OE intake will always take in 'cold' air from outside the engine bay BUT without providing any ram effect and allowing for filtration of debris and water.

I have left this bit in situ but blanked off the 'exit' into the engine bay, meaning that all air, with ram effect at speed, will go into the U shaped tube that, having removed the OE air box (as you are fitting an induction kit), provides 'cold' air in the vicinity of the induction kit's filter.

Here is a pic to illustrate what I am saying with the exit of the U tube seen by the top left corner of the filter;-

I assumed that it was something like that.

If you were to remove it and seal up the gap at the back surely that would force more air into the airbox? Obviously you risk getting water in too though so probably not a great idea.

The reason for the 'vent' is if for whatever reason the grill should be submerged or covered in water it wont be sucked into the engine and cause damage.

Think of it like a vacuum cleaner with a hole the pipe. Stick the end in the water and it wont suck it up.

Hi Jonno,

I think it is an interesting and very clever piece of design that means the OE intake will always take in 'cold' air from outside the engine bay BUT without providing any ram effect and allowing for filtration of debris and water.

I have left this bit in situ but blanked off the 'exit' into the engine bay, meaning that all air, with ram effect at speed, will go into the U shaped tube that, having removed the OE air box (as you are fitting an induction kit), provides 'cold' air in the vicinity of the induction kit's filter.

Here is a pic to illustrate what I am saying with the exit of the U tube seen by the top left corner of the filter;-

Wouldn't you get more air into the cone if you were to remove the intake and just left the gap straight through? Can't remember where the end of the pipe is situated in relation to where your cone is.

If you were to remove it and seal up the gap at the back surely that would force more air into the airbox? Obviously you risk getting water in too though so probably not a great idea.

Correct; depends of course if you are keeping or removing the OE airbox.

Wouldn't you get more air into the cone if you were to remove the intake and just left the gap straight through? Can't remember where the end of the pipe is situated in relation to where your cone is.

Yes; you would likely get more air in but you'd also get water spray when its raining. By keeping the U shaped tube and blocking the back of the intake it means that any water will exit the tube at the base of the void around the intake filter. Gravity then does the rest and keeps the water (spray) away from the filter.

I have also got a load of DIY heat shielding the base section of which stops water coming up to the filter from below when, for example, splashing through puddles.

Seen here, exit of the U tube is hidden (in this photo) by the top left corner of the intake filter;-

Did you get a Blue Peter badge for that craftwork?

That looks hideous

If you drive it with the bonnet closed you won't notice it.

That looks hideous

maybe but it works!

But looks like a fire risk to me.

Did you get a Blue Peter badge for that craftwork?

Nope! Gold medal from the University of Heath Robinson.

18 months later, all still in situ and working well; even with the really wet weather we have had recently, although not looking quite as clean

But looks like a fire risk to me.

... but if you get an under bonnet fire, your royally stuffed anyway! :eek:

The reason for the 'vent' is if for whatever reason the grill should be submerged or covered in water it wont be sucked into the engine and cause damage.

Think of it like a vacuum cleaner with a hole the pipe. Stick the end in the water and it wont suck it up.

I can understand that however if the grill becomes submerged and the water reaches the level of the intake then it's likely to also cover the intake pipe going off to the airbox anyway hence the vent is useless?

The vent pipe is facing the other way.

Now im not saying its a snorkel but if you hit a big puddle or a ford for example the bow wave would only be coming from the front up the grill.

That looks hideous

Here, here...thats awful!

Once you're happy it works, I'd probably spend a bit of time fabricating a bracket, what you have now looks a bit experimental - worth making it look right IMHO.

The stock airbox is actually pretty good though

The reason for the 'vent' is if for whatever reason the grill should be submerged or covered in water it wont be sucked into the engine and cause damage.

Think of it like a vacuum cleaner with a hole the pipe. Stick the end in the water and it wont suck it up.

Sounds like a cracking bit of design to me then

Here, here...thats awful!

It's supposed to be functional and serve a purpose. It doesn't matter if it doesn't look pretty.

my fsi engine air comes into the same part behind the grill as the picture above then goes towards the offside, down towards the floor and then back up and round to the air box (ill have to put a pic up at some point). i did wonder and did mention it at jkm about going straight from the air intake behind the grill and do a more direct route to the air box and wondered of this would help response, economy and maybe increase bhp by a few (as opposed to losing any).

You'd be going in the top half of the airbox then and be bypassing the filter. The reason the intake takes the route it does is to come in at the bottom of the airbox.