Does the 'go fast' bonnet bulge acually do anything?

[GabrielKnight]

I thought this bulge was to let more air in to the air filter for a better mix but this seems to be clipped closed? And the bulge is on the other side to the air filter. container

Am I arse over tit as usual or is the bulge just for show?

[vkosho]

The vent lets air in to cool the exhaust manifold, thats why it has the duct underneath to force air down.

As for the bulge it might be needed for clearance over the engine but ive never checked.

[Matty86]

scoop draws air in (it's a naca duct, not a vent)

standard bonnet would foul the inlet

[robi1000]

I don't think it draws air in. It does up to about 40 km/h, but then low pressure over the bonnet sucks out hot air from exhaust manifold.

[DaneC]

I don't think it draws air in. It does up to about 40 km/h, but then low pressure over the bonnet sucks out hot air from exhaust manifold.

+1

[Justin..]

http://en.wikipedia.org/wiki/NACA_duct

[GabrielKnight]

Cool, thanks for the link.

[col]

Yes that makes sense,............but do stripes over the bonnet really make the car go faster,or do i really want to see my windscreen washers lit up at night, or are neon lights really there to let cats an small voles have a disco under your motor ???...........................why do nummys do this,is there any meaning to life? :lol:

[busterhymes]

course you need all that stuff col :wink:

[col]

Cheers Buster,i thought i was loosin it............now where did i leave those furry dice, an wheel spinners :)

[busterhymes]

now ur getting the hang of it col :wink:

[Carole Anne]

Yes that makes sense,............but do stripes over the bonnet really make the car go faster,or do i really want to see my windscreen washers lit up at night, or are neon lights really there to let cats an small voles have a disco under your motor ???...........................why do nummys do this,is there any meaning to life? :lol:

Bet you have a furry steering wheel cover and a princess on board badge to :lol:

[Purple]

Is it be possible to run a 16V with standard bonnet?

Would there be clearance over the inlet manifold? Or would the engine bay get too hot?

That bonnet change with normal rims would make stealthy-looking hot hatch.

[16v_paddy]

Is it be possible to run a 16V with standard bonnet?

Would there be clearance over the inlet manifold? Or would the engine bay get too hot?

That bonnet change with normal rims would make stealthy-looking hot hatch.

I've seen it done, on prilliams iirc, just have to get busy with a grinder to resolve the clearance issues

[Laine_16v]

Hahaha we all love this argument, especially matteh ;)

How can it possibly suck in air when travveling?! THe air rushing over the bonnet is clearly faster than the air surrounding the engine under the bonnet. Therefore the air will always be sucked out of the vent!

[Laine_16v]

SOrry meant to say the air rusing over the bonnet and is travveling significantly faster than the turbulent air in the engine bay, this must mean the air over the bonnet is of a lower pressure and therefore drawing the air out.

Bring back the edit button!

[Laine_16v]

[quote="vkosho"]The vent lets air in to cool the exhaust manifold, thats why it has the duct underneath to force air down.[quote]

Oh you mean the raincatcher thats there to catch rain? :wink:

[robi1000]

Guys it's just plain physics. The faster the air speed over given surface, the lower the pressure. This is how carbs (well, venturis in the carbs), venturis on the back of sports cars and ClioIIIRS works, this is why wind can lift your roof off the house even tho it weighs few tonnes, this is the reason why race cars are sealed and straight underneath, this is why aeroplanes fly...

NACA duct is there because of it's design feature which is LOW DRAG compared to other types of protruding air scoops (like say Impreza WRX one). And the thing under the vent is a rain catcher like Laine said.

[MAXIBOY]

SOrry meant to say the air rusing over the bonnet and is travveling significantly faster than the turbulent air in the engine bay, this must mean the air over the bonnet is of a lower pressure and therefore drawing the air out.

Bring back the edit button!

yeah that why there used to duct air in on many applications... :?

[Matty86]

lol @ Laine

he's still under Strombas thumb and thinks it's a vent

you're hung up on the pressure thing (if its even true? ;)) - it doesn't 'suck', so pressure doesn't have much to do with it..

it 'scoops' air...

it's a low drag version of what impreza turbos etc.. have on their bonnet - only how it works is less immediately obvious

[Laine_16v]

lol @ Laine

he's still under Strombas thumb and thinks it's a vent

you're hung up on the pressure thing (if its even true? ;)) - it doesn't 'suck', so pressure doesn't have much to do with it..

it 'scoops' air...

it's a low drag version of what impreza turbos etc.. have on their bonnet - only how it works is less immediately obvious

ARGH!! This is nout to do with stromba, this is definately my own belief on the subject!

IT does "suck" hypothetically.

How does air pressure have nothing to do with it?!!!!! The whole principle of ducts and vents surround physics and air pressure :evil:


Ok so the your clio 16v is travveling at 100mph and the air travveling over the bonnet is 100mph...

Theres not a hope in chance the air at the back of the engine near the manifold is travvelling at 100mph, more like its swirling all over the place turbulently at a much lower speed.

2 different speeds, gosh a pressure difference, the rest is history how can you quesiton it, its basic physics?

Leave your bonnet uncatched and drive at 100mph, it rises, surprise surprise, because of the pressure difference.

[robi1000]

We should call myth busters!!! :lol: Or maybe just try it with a temperature sensor near rain catcher.

[Matty86]

oh laine :lol:

missed the mark so very much

[MAXIBOY]

IT does "suck" hypothetically.

How does air pressure have nothing to do with it?!!!!! The whole principle of ducts and vents surround physics and air pressure :evil:


Ok so the your clio 16v is travveling at 100mph and the air travveling over the bonnet is 100mph...

Theres not a hope in chance the air at the back of the engine near the manifold is travvelling at 100mph, more like its swirling all over the place turbulently at a much lower speed.

2 different speeds, gosh a pressure difference, the rest is history how can you quesiton it, its basic physics?

Leave your bonnet uncatched and drive at 100mph, it rises, surprise surprise, because of the pressure difference.

but its also travelling at 100mph under the vehicle causing the hot air to be drawn away from the manifold area creating a vacuum ..it creates a high pressure area which is why the air filter etc on works cars was put in roughly the same place to draw air in..

anyway believe what you will... :lol:

[Purple]

Just tie a piece of string at the vent/duct/scoop/hole with most of it inside the bonnet, and go for a fast drive. If string stays in, air is being pushed in. If string comes out, air is being sucked out.

[Matty86]

This seems a pretty clued up thread

http://www.f1technical.net/forum/viewtopic.php?f=6&t=7160

[robbox]

vkosho - spot on, cools manifold etc

[Wobba]

All I know is when I am sat in traffic for hours I see a hell of a lot of heat coming up from the vent...lot less with wrapped manifold though ;)

[MAXIBOY]

yeah wont work when stationary though.. :lol:

[caddy1210]

laine 16v, ive driven my clio 16v at fast passed speeds without the bonnet being locked for ages and still am and it never rises

[schakal]

:lol:

[Justin..]

Mine rises at about 60 if not locked down.

[Tommo]

Who cares if it does anything, it looks cool... 8)