Hood Vents?

[TrickSTer]

I've been following Siestarider's thread on cooling mods:

http://www.fiestastforum.com/forum/threads/7265-Aero-mods-and-cooling

and looking at wspec's new hood vents

View attachment 9089

and I am reminded of a display I saw at a Ford dealer:



No one could tell me what it was; I since figured it out to be a Mustang side window vent cover.

Hmmm, maybe these could be used to induce cool air into the rear of the engine compartment, to be extracted underneath.

 

[TyphoonFiST]

Two words.....Naca ducts.....enough with this louvered crap...

 

[vegaspyder]

Two words.....Naca ducts.....enough with this louvered crap...

The idea is extracting. He is not trying to feed fresh air into an intake or over a cooler.....

 

[Wimp Lo]

The hood is a high pressure zone except for the sides where the WRC ducts are placed as a place for air to flow out of the engine bay.

Even if you could create a scoop that directs air in to the engine bay, under the car is a bad place to exhaust it.

Auto aerodynamics can seem a bit like voodoo but there are good books out there. The best thourough introduction is probably Race Car Vehicle Dynamics published by SAE press.

 

[Dustys318]

These work great

 

[Siestarider]

I am so happy that Dusty proved these vents work. Improved aero too based on his coast down experience. Just so cool, look great, no more guessing required.

 

[TyphoonFiST]

The idea is extracting. He is not trying to feed fresh air into an intake or over a cooler.....

Naca ducts do both ....feed and let air out depending on the style of duct.

 

[shouldbeasy]

Naca ducts do both ....feed and let air out depending on the style of duct.

Just to drag this back from the dead - you've mentioned NACA ducts multiple times in these aero threads but never provided a source for them (especially the ones which REMOVE air).

The only NACA ducts I've seen are air inlets.

 

[TyphoonFiST]

Just to drag this back from the dead - you've mentioned NACA ducts multiple times in these aero threads but never provided a source for them (especially the ones which REMOVE air).

The only NACA ducts I've seen are air inlets.

I've seen them as raised outlets and flush inlets before. The raised can be used as both an inlet and an outlet...Raised type achieve a better ramming effect but create more drag where as a a flush inlet has lower drag and fits flush.....as seen here

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[jeffreylyon]

Just to drag this back from the dead - you've mentioned NACA ducts multiple times in these aero threads but never provided a source for them (especially the ones which REMOVE air).

The only NACA ducts I've seen are air inlets.

NACA ducts, as the term is commonly used, are always inlets. NACA designed all sorts of stuff (airfoils, ducts, etc.) but when we talk about a NACA ducts we're talking about a low drag inlet. Take a look at a modern hi-aero car like a DTM or LPM - NACA ducts are used on inlet ports and louvered vents on exhaust ports.

 

[jeffreylyon]

I've seen them as raised outlets and flush inlets before. The raised can be used as both an inlet and an outlet...they achieve a better ramming effect but create more drag where as a a flush inlet has lower drag and fits flush.....as seen here

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Do you have any engineered examples of a NACA duct used for a vent? Anyone can buy a pre-formed NACA duct from Jegs and chop a hole into their car but I've never seen a pro race team with real aero guys use a NACA to exhaust. It's counter intuitive for me that something that works as an inlet can also work as an exhaust.

 

[TyphoonFiST]

Yeah if you wanna buy mediocre Vents get them from jegs... I bought mine from a Calloway Corvette parts vendor in carbon fiber....rather tasty I might add....I've seen naca exhaust outlet ducts used on people's jet boats on the Mississippi river....no pics though....I'm usually drunk and screaming huge Rooster tail....rooster tail! I'm not near any boats as you can see though....I'll get one soon enough and find you!

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[jeffreylyon]

Yeah if you wanna buy mediocre Vents get them from jegs... I bought mine from a Calloway Corvette parts vendor in carbon fiber....rather tasty I might add....I've seen naca exhaust outlet ducts used on people's jet boats on the Mississippi river....no pics though....I'm usually drunk and screaming huge Rooster tail....rooster tail! I'm not near any boats as you can see though....I'll get one soon enough and find you!

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I just spent some time reading up - Google is my friend. There are plenty of articles with FEA backup showing that NACA ducts aren't as effective as scoops at flowing air but do so with less drag. For performance, you would have been better off using a scoop on your Typhoon than a NACA (bling is subjective). Nothing I read said anything about carbon fiber flowing more than polycarbonate (the "mediocre" ducts from Jegs). Take a look at engineered examples like on pro-team race cars - nobody is using a NACA duct for an exhaust. If there was a .01% improvement with a NACA duct you can bet they'd be using one.

That people are running NACA ducts to vent exhaust on the jet boats that they run on the Mississippi doesn't really counter the high-dollar pro-team aero design, roster tail or not.

 

[TyphoonFiST]

I just spent some time reading up - Google is my friend. There are plenty of articles with FEA backup showing that NACA ducts aren't as effective as scoops at flowing air but do so with less drag. For performance, you would have been better off using a scoop on your Typhoon than a NACA (bling is subjective). Nothing I read said anything about carbon fiber flowing more than polycarbonate (the "mediocre" ducts from Jegs). Take a look at engineered examples like on pro-team race cars - nobody is using a NACA duct for an exhaust. If there was a .01% improvement with a NACA duct you can bet they'd be using one.

That people are running NACA ducts to vent exhaust on the jet boats that they run on the Mississippi doesn't really counter the high-dollar pro-team aero design, roster tail or not.

I used a Naca vent due to its Aerodynamics/less drag and its purpose of letting cooler air into my custom airbox I made. It worked great for my purpose. Besides its purpose I haven't seen one used on a Typhoon and I wanted to be different....I always go by "To go nowhere ....follow the crowd!" Its the same with my Turbo setup and all the stuff I'm about to incorporate into my car soon when I do a mass exodus of my stock parts coming up. Keep an eye out for any of that stuff so you can patronize me more!

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[jeffreylyon]

These work great

Are these still available? I'm about to pull the trigger on a set of Verus Engineering vents but I think that the consensus is that these are better placed.

 

[cxwrench]

I've only ever seen them used as intakes. By their definition they are an intake. They are a low-drag inlet/scoop that takes advantage of positive surface pressure. Not as effective/efficient as a protruding scoop but more aerodynamic. Just because some bubba uses one as an exhaust outlet doesn't mean that's part of their intended purpose.

 

[shouldbeasy]

Are these still available? I'm about to pull the trigger on a set of Verus Engineering vents but I think that the consensus is that these are better placed.

The placement is key - any vent would work in THIS location as it's a low pressure area which should draw air out of the engine bay if it were vented.

 

[jeffreylyon]

The placement is key - any vent would work in THIS location as it's a low pressure area which should draw air out of the engine bay if it were vented.

I guess I should have asked if vents that fit in this location are still available. In the meantime I found some at Sico:

https://www.sico-developments.co.uk...vents-for-fiesta-mk7-st?variant=6833405067330

... but that's a pair of big ass holes!

 

[M-Sport fan]

I am so happy that Dusty proved these vents work. Improved aero too based on his coast down experience. Just so cool, look great, no more guessing required.

Yeah, I want a carbon fiber hood with those already incorporated, so that I don't have to hack up my factory hood,
Sadly, NO ONE (unless you can convince M-Sport to sell you one for BIG $$$$$) is doing those yet,

 

[flip314]

I know this thread is a bit old, but I found these.

https://cmcomposites.co.uk/shop/ford/fiesta-parts/fiesta-wrc-bonnet-vents

I'm digging the location and they're not as visually obtrusive as the Sico/Airtec ones.