When I slapped the turbo on my car, I was trying to save dollars everywhere I could. That led me to the questionable decision of buying a $10ish air filter, which instead of being oiled cotton was basically just knockoff Scotch Brite tucked inside cheap plastic. It was starting to melt, and the plastic retainer was cracking. Oh yeah, and the whole thing was coming unglued from where it mounts.
Not learning my lesson, I bought the cheapest K&N filter, which cost a whopping $30 on eBay, plus a ludicrously cheap tube assembly with a ready-made hole for my valve cover vent. I had to relocate the power steering resevoir a couple inches and angle it slightly to shoehorn it in.

Before:
https://cimg0.ibsrv.net/gimg/www.mia...e224edcb8d.jpg

Power steering reservoir relocate:
https://cimg3.ibsrv.net/gimg/www.mia...a6ac76a162.jpg

After:
https://cimg4.ibsrv.net/gimg/www.mia...95031b854a.jpg

Note also the beautiful wrinkle black and flat grey lettering. I feel pretty damn good about that. Now people know for sure it's a Mazda, and that it has 16 valves.

I'll probably toss an oil separator on the hot side valve cover vent because it's kicking off a solid bit of oil... leaky valves maybe?

That valve cover looks amazing. I wanna do that to mine, the wrinkle with grey lettering looks really nice.

Thanks! I wanted something that looked good but wasn't really in-your-face. I used Testor's paint with a blunt-nosed syringe to fill in the letters.

I think I'll want to box in the intake. I saw your post from 2009 and it looks like you did a great job. What material did you use for the box (assuming aluminum, but what thickness) and how has it held up over the years?

When I built it, I used sheet metal, really thin stuff from Lowes. It was flimsy but otherwise worked well. If I made it again, I'd use a thicker metal for rigidity, and probably use aluminum as it's easier to work with. It held up great, never had a problem.

I picked up some thin aluminum sheet at Home Depot Racing, which I think I'll be able to cut with tin snips. If not, I'll at least be able to blast through it with a multi purpose cutting bit on the dremel instead of having to use cutting wheels.
I'm thinking about where the cold air will come from. There is a bit of a gap where air could come from the wheel well, but I don't think that's a high-pressure area. The hole behind the headlight is filled to almost a perfect seal with my IC piping, and the NB2 doesn't have anywhere to cut a big enough hole to pull air from the cowl area (which was my plan A).
Has anyone done an over the radiator duct to bring in high-pressure cold air? The opening a the front of the car is obviously too big for efficient IC and radiator-only air flow, which is why all the race cars block much of that area off. what if I did something like this to pull air over the top into the cold air box?
https://cimg9.ibsrv.net/gimg/www.mia...fec1be4c46.jpg

You can cut the whole behind the headlight a lot bigger, or put another one, and pull air from there, or even duct air to that area from the bumper opening.

Pat is chocked full of great ideas. I find that the headlight areas get some decent cold pressure around the radiator, just a little ducting.

Thanks Pat, I think that's a great idea. I just need to make 50cm^2 worth of holes in that area and I'll be good to go. I've got the Dremel charged up, so I'll have at 'er this week!

Wheel wells are high pressure, fwiw. Thus the upper fenderwell louvers on cars in classes that allow them.

https://cimg6.ibsrv.net/gimg/www.mia...0b9969d842.png

+1 for a tops looking valve cover :-)

I had the thought of routing the intake pipe into the bumper directly to sit on top of my sealed off ducting. I have a NA with the artech efr manifold that places the front plane of the turbo almost in line with the headlight motor.

That would be sweet, but my intercooler piping is already taking up the obvious route to in front of the radiator.

I threw together a little air box this morning. I think it came out pretty well. I didn't bother doing any extra ducting because there are already 3 places cold air is coming into that spot - around the radiator, through the wheel well, and the cracks around the IC piping. I think the area of those spaces combined is greater than the cross section of a 3 inch pipe, plus they are high pressure zones.

https://cimg5.ibsrv.net/gimg/www.mia...b9dfa81988.jpgRough shape. All the pieces taped up together are because I subscribe to the don't measure and just keep cutting school of fab work.

https://cimg9.ibsrv.net/gimg/www.mia...38bd3a4972.jpgYeah, pretty janky.

https://cimg0.ibsrv.net/gimg/www.mia...d6a1022adc.jpgTraced out to fresh cardboard, and I grabbed the shape of the hood using the skewer method. I saw this in a post on this forum from like 2007. I wish I had made note of the poster so I could give credit for the idea.

https://cimg3.ibsrv.net/gimg/www.mia...45e89aeabf.jpgTraced out to aluminum. I had pulled out two skewers before taking this picture. Top tip - do one more step and trace from skewers onto fresh cardboard. I spent way too much time trimming the aluminum to fit.

https://cimg4.ibsrv.net/gimg/www.mia...778b1280c4.jpgI threw some edging all the way around, and used aluminum tape to seal off a couple spots.

https://cimg6.ibsrv.net/gimg/www.mia...69503b8f48.jpgFinal product. I think it turned out pretty well. I didn't bolt it in at all, just press fit, and then the filter, IC piping, and hood will keep it from moving around too much.

The biggest flaw in this design (if you can call it that) is that there is a pretty big gap at the front edge by the radiator. I didn't want to put a front wall because I want the high-pressure cold air that gets around the side of the radiator, but I don't want it open a the top to the hot air from the engine. I had to trim back the front much more than I wanted to so that I could put down the hood prop rod, but I could have done a lot better. ¯\_(ツ)_/¯

Looks good! Should give you pretty good air temps.

The "skewer method" can be properly attributed to Hornetball.

What did you use for edging?

Thanks, and thanks for the idea @hornetball!

This stuff:
https://cimg8.ibsrv.net/gimg/www.mia...c7f5f1bfb3.jpg

I thought it was kind of crappy because it doesn't stay on. Then I realized that you need to squeeze it with pliers once it's in place and then it stays on really well. It's got metal inside. I got a couple projects out of it, and it only cost me $9!

I meant to route the intake for the turbo over the radiator like some people do intercooler pipes; shrouding like a box (like you see on Andrew's Rover but with a stock bumper) up to the radiator to allow room for the intake on top. Hoping to go through with it after I have an intercooler, post some photos in case anybody pulls ideas from it.

That's a really interesting idea. Even if there isn't really enough room, a 3-inch silicone tube could be squished a bit and still provide a lot of volume. I love what ThePass did, sticking the air filter right out in front of the well ducted radiator in a high pressure zone. I'm looking forward to seeing what you come up with!

I just ordered new wheels and tires. I'm sticking with 17s both because I'm a stance bro at heart, and because I really liked the first ones. I just got the exact same wheels (TR FF10) but an inch wider at 17x8. They are flow formed and tip the scales at 17.1lbs in the wider format, which is really not too bad. I'm going with the Falken RT615K+. Wider and stickier, I can't wait!
https://cimg6.ibsrv.net/gimg/www.mia...1721e63850.jpg
Some of that real sticky icky icky. Ooh wee!