Hobo Hybrid Airbox Part 2

Alrighty...since I wrote the original 'hybrid airbox for a tenner (ish)' how to guide most of the comments/questions/feedback have been about the absence of a secondary air feed. The weather finally cleared up a bit today so I thought i'd have a bash at sorting something out. The cost of adding the additional feed is ....wait for it.....£1.49. The only part you need is another one of the roundline downpipe connectors you bought from Wickes to make the original filter mount.

First chop off all of the fattest section just turn it every so often as you're cutting and all will be well



Firstly I've decided to mod the bottom half of the airbox for a number of reasons;
1) that's where the original secondary feed comes in
2) the back of the airbox base is pretty much flat and runs parallel to the firewall. This makes cutting and aligning of holes significantly easier.
3) if you were fitting any other hybrid filter all these bits would have to come out anyway so its no extra hassle
4) if you decide to revert back to a stock airbox lid you still have a nice secondary feed, either that or you could use this mod on its own with a K&N panel filter. There's nothing really stopping you doing this if you already have a Dave F fitted as well

Remove your existing airbox lid and put it to one side as you can see here the original conversion is still going strong



Next remove the airbox lower section (there are numerous threads about this dotted around the net)
This next pic shows the section of pipe connector offered up ready for marking up. Pencil is fine for this.



This pic illustrates pretty well the increase in feed size you're going to get. Its exactly the same size as the primary feed.




Now its just a case of removing the area you've marked out. It's pretty thick plastic but if you drill a series of holes round the inside edge of the circle you've drawn on you can just knock out the section and smooth it out. If you can get your hands on a Dremel it would prove useful in this and the next step. I had to rely on a black and decker.



Take your time and keep checking as you go. I smoothed mine out with a stanley knife (carefully) then used some rough sandpaper wrapped round an old half-round file which made short work the initial shaping then a finer grade for the final shaping. You want it to be a tight fit as this well avoid the need for sealant. Fit the bit of shortened pipe from the inside like this...as long as you haven't over cut the hole it'll be wedged in very tight. You can seal it if you like but don't do this till you've measured up for the scuttle hole





apologies for the crap iphone pics by the way. This is one to show how much space there is for air to flow into the box



Trial fit it in place and mark up for the corresponding hole in the scuttle which you can then remove and cut using the same technique off the car (it's thinner and easier). It should look like this when the scuttle is refitted





You now have a nice big air feed



Give everything a clean, reassemble, job done! :thumbup: