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View Full Version : a question about the bonnet vent...



titcharoony
15-07-2007, 15:50
has anyone heard any info on to how much (if any) the bonnet vent aids cooling? from what I can see it feeds air to the exhaust manifold? Is it purely cosmetic aka fiesta rs turbo, or does it do a significant amount. My friend claims most benefits are found after turning engine off as heat from engine bay can seep out quicker. Thoughts facts and opinions people...?

clio_rsi_turbo
15-07-2007, 16:16
i think its there to just help keep temps down, produced from the manifold.

BRUN
15-07-2007, 16:17
as far as im aware it doesnt work like a cooling 'hole'

as the air comes across it as you drive, the hot air is sucked out

very basic description but thats how i understand it works

drsmith1979
15-07-2007, 16:58
surely that would only work if the vent was perpendicular to the air flow? i.e. mounted sideways on the bonnet instead of head on?

it appears its simply to channel cold air into the exhaust manifold area indirectly due to its rain catcher style design.

big hp
15-07-2007, 18:03
as far as im aware it doesnt work like a cooling 'hole'

as the air comes across it as you drive, the hot air is sucked out

very basic description but thats how i understand it works


As brun says it draws hot air out of the engine. Hence when the engines hot you can see the heat rising.

jwarren2k2
17-07-2007, 21:04
it lets hot air out when it rises, but cold air doesn't go in it as such.

Next time it rains, jump on the motorway and watch the pockets of water collect on the 'bulge', none of it goes into the vent, which in turn, should show that the air isn't channelled into the vent.

Thats my opinion anyway! lol

Clio_GTT
17-07-2007, 22:18
as brun says it almost creates a vacuum effect at the back of the vent and draws hot air out. plus the bulge is there to cover the inlet manifold

Purple
18-07-2007, 01:13
It works similar to the venturi exhaust vents on the back of motorcycle helmets. The big hump on the leading edge of the bonnet creates a low pressure over the vents and hot air get sucked out the faster you drive. If you have the misfortune of driving on flooded roads, you will see a wall of water vapour exiting the vents, not recommended but pretty cool when that happens :)

BRUN
18-07-2007, 18:30
woo i was right lol