Cold Air Feed

[JonLeeper]

Now I am aware that the subject of aftermarket filters has been done to death but I have a slight variance on the theme and was wondering about the perceived wisdom of the masses! 

I need to do some work on the air intake on the 8v, as I think that is where the oil was getting into the intake on my day at Brands, and remove the breather and fit a catch tank.  So I noticed another Mk2 on the day who had a bonnet vent fitted and was getting a direct cold air feed from that.  Thinking about this it makes great sense, but I was talking to a number of very knowledgeable people who said that a NACA duct would be a better fit.  It would not upset the airflow over the car and could be placed further towards the front of the bonnet and thus in a high pressure area.  The idea would be to create a fibreglass (?) box in the engine bay to isolate the filter and feed this from the front edge via a 3“ NACA duct towards the front of the bonnet.  This then leads me onto the argument about best / least restrictive filter arrangement.  Now IN THIS INSTANCE with a proper box to control the airflow and any excessive noise would it make sense to fit some form of cone filter or just box round the existing box?

Over to you all.  Many thanks,

Jon

[Diamond Hell]

I don't think you need some sort of 'ram air' system of getting air into the intake.

If you look at research on this sort of thing you'll find that the torque and power curves were plumped up the best using a good quality panel filter and an appropriately sized velocity stack coming in to the lower part of the airbox.

If you ram too much air in there you're going to throw the ECU miles across it's tables where it's expecting to be, so things will potentially start running lean/rich and you may dig up all sorts of weird running issues.

Try and remember that however much air you get in the bottom of the box it's still got to go through that stupid flappy swinging AFM, so until you've lost that out of the system and got some proper management on it you're pretty much p*ssing in the wind trying to maximise power output from the engine.

HTHs

[adamhhr]

if its a big bumper model look on swg they do a air intake from the splitter