Bonnet Vents

Massive

Torque Master
Points
72
Location
Weir
Car
Clio 172 Cup
ok a few questions ive found some vents i like, also ive found a few bonnets with vents already on them!

but how easy are vents to fit, without showing the lines where you have cut, is it a pro job?

also im lookin at a carbon fibre bonnet, yes its expensive :s but would look good in my opinion with the colour of the car, but can you put vents into carbon firbre bonnets, or would they look stupid if they were not carbon as well?
 
so if i get a a carbon firbre bonnet i would be best to get carbon fibre vents, think i might look for a carbon bonnet with vents already in, or if not see what a body shop can do for me *gulp*
 
In my mind it's not the cutting that would be the hard part, it would be the positioning of the vents making sure they are straight & symmetrical. I think buying a bonnet with the vents in would be bestist :amuse:

Lets have some pic's then Massive, what's on your shopping list :bigsmile::bigsmile::bigsmile:

**If you do get a carbon bonnet & you plan to fit the vents yourself, make sure you wear a breathing mask when cutting. Some Carbon fibre parts contain 'Carbon Nano-tubes' which add to the strength of the part, but may (it's not 100% certain yet) damage lungs in much the same way as asbestos if breathed in.**
 
dont think ill be doin any cutting ill probably make a mess of it, sorry ill have to get some pics up been busy, my rover cost me 600 quid :s has had a full engine rebuild after the head gasket

it needs the mot now, needs 3 new tyres and rear susp bushes :s
 
I've actually been considering bonnet vents to funnel some air down the back of the engine bay to where the turbo is (hidden away, out of the air stream!!)

What's the likely cost to get this done professionally?
 
Do not try cutting into carbon fibre. If you ruin it, you cannot repair it! I've got a bonnet with the vents already in. That cost me £500.
 
I've been thinking of cuttin some holes for vents in my bonnet as my engine runs very hot. But my question is. What about the water that it lets through? What happens to it? Would I need to place a tray under the vent all the way to the front?
 
im sure unless you drive through a river you would be ok lol i mean im no expert but you would need some pretty intense rain to flood your engine.
 
I was just worried bout the air filter an the electrics? Would I need to put vents in or could I cut the holes and put mesh behind it? Would that let too much water through? What about when the car is stood an it's raining?
 
err i would imagin unless the angle your filter is at ie facing down or level it should be ok i mean if you had a vent on the bonnet the filter would no normally sit right in it normally behind it. so its all about position but i would put a strong grille if its larger like a scooby vent or evo vent but i would put some mesh if its just small
 
I was thinkin of having 3. 1 between the radiator and the engine. It would be about the manifold. And 1 either side around where the airfilter sits. It's a mod that will have to wait cause if I do, do it then I want to make sure it looks right...
 
ok so the radiator one i would imagin to be a hole like an evo and the other two aswell im sure cold water on the radiator would not be a prob plus the manifold will sort that out because of the heat where does the air filter sit do you have a pic of your bonnet
 
it will take time but mostly common sense lol its shouldnt be too difficult why even see ive there is already bonnents for your car and see where they are positioned
 
it will take time but mostly common sense lol its shouldnt be too difficult why even see ive there is already bonnents for your car and see where they are positioned

I had thought about this but if I do it I want it to be individual and of my own thought. It will take a lot of time and thought to do this mod I think.
 
ok a few questions ive found some vents i like, also ive found a few bonnets with vents already on them!

but how easy are vents to fit, without showing the lines where you have cut, is it a pro job?

also im lookin at a carbon fibre bonnet, yes its expensive :s but would look good in my opinion with the colour of the car, but can you put vents into carbon firbre bonnets, or would they look stupid if they were not carbon as well?

What are you trying to achieve; air in, air out or just posing?
 
haha posing i think he wants air in because he is talking about it near the air intake but also by the radiator and manifold so maybe both
 
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What sort of duct are you thinking of HDI, something like a NACA duct?

I don't know, that's the problem. All I want to do is scoop some air down the back of the engine compartment without making the car look silly or become noisy. There's a lot of control gear at the back of the engine bay - all the turbo control vacuum valves are located there so space is very tight.

The car already has an oil/water heat exchanger as standard so perhaps an additional oil cooler mounted at the front would be better that vents. Same problem though - where the heck do I put it?

I'm open to suggestions on this one
 
I want air in/ out so I can cool the engine abit...

Air flowing over the engine will do BA in the cooling department, that is what the radiator is for. If the engine is overheating (and timing etc is correct) you need to improve the efficiency of the heat exchanger. This can be done in various ways.

Make sure that ALL of the air entering the intakes is channelled through the radiator (ie none of it escapes around the edges).

Make sure that there sufficient pressure differential between the two faces of the radiator in order to achieve an efficient flow through it. If the air can't get out once it has passed though the radiator it will severely restrict flow and therefore heat removal. There is no point in putting more intake scoops on if the extra air can't get out! You may well find that the fitting of an air OUTLET has more effect than in inlet as it allows the existing radiator to work more efficiently.

Look into fitting a more efficient radiator. Even one the same size can be better if a more efficient core is utilised.

Positioning of intakes and outlets is VERY important if they are to perform properly. Intakes need to be located in areas of high pressure (relative to where the air is going) and outlets in low-pressure areas, otherwise you are wasting your time and money. A scoop placed at the front of the bonnet will not flow more air into the engine bay if the pressure under the bonnet is higher than that outside, no matter how fast you are going.

If you are only interested in aesthetics, then ignore the above :) Bear in mind, however, that a badly placed scoop could actually impair your cooling by messing up pressure differentials.
 
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Thanks for the tips mate. The main idea is just to release some heat from the engine bay. When I open the bonnet after a good drive I get a massive wave of hot air thats been stuck under the bonnet I just wanna relieve that Tbh..... There will be a lot of thought going in to this before I decide where i'm gonna start cuttin with the grinder....:D
 
Look into fitting a more efficient radiator. Even one the same size can be better if a more efficient core is utilised.

A good article that Old-git :D

Am I right in thinking that a cheap(ish) route is to fit a radiator from an equivalent diesel model?

Here's a pic' of the bonnet that's on my car, the vent is positioned right over the exhaust manifold. **Edited this is my car!!!**

loz-albums-my-marmite-car-picture1897-vent-fibreglass-bonnet-allows-heat-out-manifold.jpg
 
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A good article that Old-git :D

Am I right in thinking that a cheap(ish) route is to fit a radiator from an equivalent diesel model?

Here's a pic' of the bonnet that's on my car, the vent is positioned right over the exhaust manifold. **Edited this is my car!!!**

Thank you, I try my best :)

I know nothing about diesel rads, perhaps HDi can help.

The vents by the windscreen are in an area that is usually a high pressure zone (that's why heater intakes are placed there) so air will tend to flow into engine bay. The front scoop is in an area of low pressure on cars with a relatively streamlined front end, so air may will try to flow out.

However, it is easy to check this. Attach a few short lengths (50mm) of string or wool to the bonnet just in front of the scoop (as close to the opening as possible but parallel to it) and on top of the rear grills. Go for a drive following a couple of friends in another car. The passenger will be able to ascertain whether air is flowing in or out of the scoop and vents (photos will help).
 
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Thank you, I try my best :)

I know nothing about diesel rads, perhaps HDi can help.

The vents by the windscreen are in an area that is usually a high pressure zone (that's why heater intakes are placed there) so air will tend to flow into engine bay. The front scoop is in an area of low pressure on cars with a relatively streamlined front end, so air may will try to flow out.

However, it is easy to check this. Attach a few short lengths (50mm) of string or wool to the bonnet just in front of the scoop (as close to the opening as possible but parallel to it) and on top of the rear grills. Go for a drive following a couple of friends in another car. The passenger will be able to ascertain whether air is flowing in or out of the scoop and vents (photos will help).

Or buy a wind tunnel :D
 

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