Nope. Very little enters. Open your window on the freeway, not much comes in. Now imagine your car is hotter, you're in a helmet and safety gear, and you're working fairly hard to muscle your car around track. It all ads up to not enough air without vents.

it seems like the exact opposite, like the inside air gets pulled out. Ive never used these naca ducts but several track friends said they are very affective. personally the heat has never bothered me much inside the car
from experienceexecpt sitting in the paddock which kinda sucks.

I think psrenyol is right, the windows open at high speeds great a vacuum pulling the air out of the car. Plus it's so damn loud. The NACA ducts work great. I have seen scoops that offer even more airflow from the NACA ducts

I have the snap out flap kind in one car and the NACA duct in the Spec. The NACA ducts pull in significantly more air. I could definitely see them sucking in flying track debris and directing it at your face. The airflow feels good though.

Bob

You could put wire mesh in it if you're really worried about debris. I have a couple NACA ducts laying around that have it riveted in.

I find those NACA tube ones obtrusive. The NACA ducts you use for headlight NACA ducts seem better in terms of being less obtrusive

Thanks for the comparison. I am going to put a set of these NACA vent ducts in my track car. As far as the track debris, I could see that happening LOL. Freaking rubber bits flying everywhere sometimes. A piece of coarse wire mesh over the exit end of the duct would help with that.

Keep in mind for those reading this thread whether or not your racing and/or HPDE organization allows you to have the windows up. NASA, where I race, requires the front windows to be completely rolled down. Mine is actually removed from the car completely. So a venting solution that uses the rollup window will not work in my case. But the NACA vent windows will.

double post

do they leak?

they probably won't if you put some sort of plug in them.

iirc, levnubhin had some in his red car (dd in s. florida, where it rains often)

Bob u so dirty.

The Weekend Racer NACA duct version looks huge. The ducts do not need to be that big to work.

There is a smaller clear lexan version available. I have one of these in place of each of the front quarter windows. They work awesome. The NACA duct is pop rivited to a piece of clear lexan, and installed like a normal quarter window. The NACA is installed at the base of the window, perfectly parallel with the bottom edge (and not tilted up as shown in the Weekend Racer photo).

The outlet points right toward my chest and feels GREAT at speed. As other said, it really does move a lot of air. I use caps from Rustoleum spray paint cans to seal off the duct when I'm towing the car. The caps also work great for track use to keep the rain or cold air out on wet / cold days. I push the caps in from the outside and have never lost one in transit or on-track. I have lost them around the garage or pits though, but luckily, they are cheap to replace. :)

I wouldn't want them on a street car, but love 'em on the track car.

I see it in your sig pic

do you do anything to direct the pass. side airflow?

So, what's the consensus on these for a street car? I like the idea, and now that i'm driving my car a ton it seems like a great idea for my non-ac car on those 80+deg days.

Nope. As a track-day instructor, I have the passenger side vent for...passengers. The driver side puts out plenty of air for me. I sometimes run with it plugged on track (don't bother or forget to remove the plug). Either way, I've never noticed a difference in airflow from where I'm sitting.

On a street car, I wouldn't run them. Perhaps look into the "cool breeze scoop"? At one point they were making them to clip onto the side windows. A friend of mine was beta testing for them a year or so ago.

I've done a lot of time with mine on the streets, the paint cap works great. If it's truly cold (less than 40) and I need to drive it on the streets for some reason, painters tape seals up the paint can cap rather well.

It's good enough for me that it keeps the rest of the cockpit cool, just moving cool air in and pushing hot air out the window. Or at least that's the goal.

I have the snap vent style ones in my street/track beast with no AC they flip out and you can close them and they are also adjustable some what for flow direction and volume so they are pretty cool. Lot less blasting your ear drums with the window down on a long freeway trip in the hot sun and you still have good flow. I would recommend them for a street car with no AC. Just don’t ever assume locking your doors does anything they snap out easily and you can reach the inside door lock with your arm through the hole. The NACA style ones simply flow a lot more air into the cockpit and you should have eye protection if you have them.

Bob

I love mine on the street, as I wrote previously. Great for putting some air on your face in an AC-less car.

https://www.miataturbo.net/attachmen...7&d=1339114392

I know. That's why I did this. Used a wilwood cotterpin to keep them sort of locked in place when the car is parked.