Zspeed Undertray and Brake Ducting
 

Casually reading through some threads about brake cooling and noticed that an issue popped up was how to install brake ducts for bumpers other than the ones Stillen is pre-made for ('09-12 factory bumper + Stillen facia) or Nismo (RC or copy thereof from Synergy or Finite)

I have a 2015+ Nismo. There's no off-the-shelf solution for hooking up brake ducts without hacking up the bumper for some universal ducts.

For a race car, no problem:
https://live.staticflickr.com/65535/...ca30040b_b.jpg

Doesn't look half bad

But is there a solution without hacking?

Then I found this thread:
http://www.the370z.com/brakes-suspen...t-install.html

Basically, this dude mounted some NACA ducts on his Zspeed undertray. Wicked solution

However, when i see the 2015+ nismo zspeed tray, it has this dip in the middle:

https://uploads.tapatalk-cdn.com/201...ff1e5a59f6.jpg

So i was thinking?

Why not cut a couple holes as pictures here:
https://live.staticflickr.com/65535/...9d261871_b.jpg

Rivet on these:
https://static.summitracing.com/glob....jpg?rep=False

Connect the hoses, and viola?

Could even put some mesh in between the opening and the flange to block rocks

conceptually . . . would that spot pick up enough air to be worthwhile?

It likely would. The Zspeed shroud for my '14 Nismo has a 6 inch slot cut in that slant to allow airflow over the bottom of the oil pan. Don't think they'd put it there if it wouldn't work...

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Yeah, that thread that the guy installed NACA ducts into his undertray was a great idea. I don't see why couldn't do what you are thinking. The only question would be airflow, are you going to have enough.

Yup, thats what i was worried about

Alternatively, i could try to just mount the naca duct on the flat side like that guy, it's just a matter of whether theres enough space to do it. The Nismo v1 has massive surface area

i dont have any components in hand to measure anything, i'm just spit balling based on what i can find diagrams of

I have 2 of those duct pieces for 3" hose if you want them. $10 for both plus shipping. PM me.

After studying more pix, my concern is that the holes i put on the diagram will be right near the oilpan

Anyone know how much clearance there is behind that sloped part of the undertray?

The oil pan is there. I don't know what the dimension is right there. You might not have enough to use a 2" hose without ovaling it.

Sub’d

Just do this

He’s got one that looks like this; unsure surface area on these :ugh2:

Go right under the drl’s.

If I had that version of the nismo it would be that simple

I'd rather not cut up a 2015+ nismo atm

If it came to it, I'd put a NACA duct as you described right under the dyrl

Only real way to see if they work if to buy a heat gun and test before and after

Before going through the custom duct work, maybe cut the hole where indicated, and mount a small handheld anemometer there to see what kind of wind speed you get in that opening?

Also, I would think having fender vents (like the Nismo GTR ones, or the FE Design ones) may help with drawing air from under? After all, reducing air pressure in the wheel well makes it easier for fresh air to enter. Just a speculation.

Just keep in mind a big driver of airflow in this case is the pressure difference between the inlet and outlet, not just the air velocity aimed at the inlet. I doubt very much that the pressure at that point [on the undertray] is anywhere near as high as the front surface of the fascia. I mean I could be wrong but...