NACA ducts, can they be used as engine air intakes?

[Christian_C]

I've been having a bit of a think about these little ducts and about the applications they are/could be used for. For anyone who doesn't know what one of these is: http://en.wikipedia.org/wiki/NACA_duct

Now, these things are quite often used on race cars for cooling purposes of things like brake discs and engine cooling but they are never used as a form of air intake for the engine.

I've looked around a bit to try and find out why but I haven't found anything as of yet that gives me an answer as to why they aren't used as intakes. The only thing I could really find was that using a scoop for an air intake is more effective than a NACA duct.

The question I'm really trying to ask is could a NACA duct be used as an air intake for an engine if the possibility of a scoop was unavailable? or is there a critical reason why NACA ducts aren't used as engine air intakes that I haven't found out yet?

Many thanks to anyone that can provide me with information

 

[Bottoz]

Yes. It's a hole that air flows through.

http://revlimiter.net/mods/duct.php

http://sports.racer.net/tech_info/aero/naca_profile_calculator.xls

 

[benzoboy]

The Lancer Evolution 4/5/6 used a NACA duct as standard I believe

 

[Christian_C]

Yes. It's a hole that air flows through.

http://revlimiter.net/mods/duct.php

http://sports.racer.net/tech_info/aero/naca_profile_calculator.xls

Thank you That top link is exactly the idea I was thinking of (I have a '90 Miata and was thinking of that exact idea but wanted to check to see if it would work first )

Thanks for the link, I have a feeling it will prove invaluable when I get round to doing it

 

[motortrend]

I remember reading somewhere that the NACA duct on the RUF CTR "Yellowbird" had a negative effect and that is why they where removed on the later cars, but that may be a metter of placing: