Been trying to find a way to direct fresh cold air into my intake system. Since my front end is pretty much all sealed up, I found another way is to get fresh air from the high pressure zone under the windshield like Randall Cowl Intake. Here is my design 3D printed in PETG. Please let me know if you have any idea to improve my design.

 

I'm not sure the temperature range for PETG, but assuming you don't have a problem there then it looks like a sweet swetup. How much difference is there in induction sound?

 

This is awesome. Following.

 

Looks great, you selling these?

 

Hot damn! This is sweet!!

 

We had NACA ducts and fender vents printed outta PLA and are holding up fine, I used PETG cus I it’s more chemical resistant and can hold up to 135C. My car is kinda loud I don’t hear much from the front

 

ya, I’d sell this too if anyone like the design. The inlet duct on firewall should fit all NA/NB, but the outlet is made to fit my Flyin’ Miata intake box. unless u have something similar with a flat mounting surface.

 

any way you can prove that it works? Like, air speed sensor in pipe. Or just do a run and log IAT with and without?

 

airflow from that high pressure zone is proven, I sticked wool around the openings on the firewall (on both passenger and driver) and saw them got sucked in. I was having engine overheating issue on track. Talked to super Miata and flyin Miata crew at Laguna Seca 2 yrs ago(they’re super helpful), decided to block them because the air flowing in from there created higher under hood pressure and countered the airflow from the front so it affected my radiator cooling. after blocking them with duct tape, coolant temp dropped 5-7C so I kept them blocked with an ABS panel (u can see on my passenger side). Many intake systems get air from the cowl ( including the one you can buy from Flyin Miata) and even the stock interior fan blower is getting fresh air from that channel, so I started this design. Although the theory is solid but I do plan to test it with an anemometer to see IAT and CFM improvement. But due to the current pandemic track events are all cancelled. So will test it later

 

Your FM cold air box was already getting air from beneath your headlight. So the question becomes which inlet is better: below the headlight or the cowl. To find out you would need to block one while you test the other, as I see it.
DNM

 

I want the cowl inlet. What diameter hose is that? I hope 3in so it doesn't restrict flow more than the inlet of the turbo itself.

 

Great logic, checked and didn’t have much coming in from the front. Put some wool strings there and try taking video with GoPro, they didn’t move at all. In comparison to the wool sticked on the firewall opening, they floated right in. Else I won’t waste time on this.

 

2-5” hose. 3” won’t fit there under the hood, but 2-5” tuck right in.

 

Well, I've already got some 2.5in high temp brake ducting left over so I'd be honored if you would print one for me.

 

Awesome, thanks for explaining the high pressure area. I wasn't aware that it was that strong. It explains the long black foam gasket running along the hood. I always wondered what that was for.

If you can make the files available so we can print them, that would be great!

 

Thanks for your interest, pm me if you wanna get a set.

 

Im a bit of a ricer.. I wonder if one could be designed to route the tube through the fender for a really clean look in engine bay..

edit: I doubt it.. this really looks awesome.