Bonnet vents

[dest]

I doubt it would affect the grill much, if anything just reduce the gap at the bottom very slightly

[Rusty]

Yeah, it's about 20mm height difference in 1m so that's 0.1degrees Don't think you'll notice that... It's just getting the bracket offset so that it fits and clears everything, easy to do but having not really looked at it I can't tell for now.

[anton]

ah right, if your getting hot then yes good plan and i suppose when getting air out you'd probably wont effect the rest of the air flow so could give good results. the reason the wing vent is a problem is because a hole perpendicular to air flow causes a vacuume and would lead to air being sucked from the intake, ideally you want high pressure, cold static air, something you can only get with a cold air feed into an airbox, and i mean airbox in its literal term, not necissarily a standard item, i had one on my gold and fould it to give much more noise but no effect on power, possibly even detrimental.

Ant

[twoqu]

I don't know what he is saying but there are some pics to look at!

http://www.audis2fast.de/haube.htm

[dest]

They wont do a thing in that position! Vents have to be at the front to do any good.
They are from a 4x4 Sapphire Cosworth if anyone is wondering

[Rusty]

ah right, if your getting hot then yes good plan and i suppose when getting air out you'd probably wont effect the rest of the air flow so could give good results. the reason the wing vent is a problem is because a hole perpendicular to air flow causes a vacuume and would lead to air being sucked from the intake, ideally you want high pressure, cold static air, something you can only get with a cold air feed into an airbox, and i mean airbox in its literal term, not necissarily a standard item, i had one on my gold and fould it to give much more noise but no effect on power, possibly even detrimental.

Ant

As I suspected, you get low pressure at the front of the airbox. I was toying with a NACA duct at the front of the bonnet but I don't think there's enough room there. A NACA duct on the side would work well or a scoop but that'd look poor. Best bet is to get a reverse inlet and then you can run a pipe to the grille nice and easily

Cheers Robin, looks like he's grafted some Cossie vents (as Dest poseted) into the bonnet, they look pretty good but are too rounded for me, I want some sport quattro rectangular ones.

They're somewhere near the right place IMO as you have to remember how far forward the engine sits in the old S2s and we're not talking of ducting air under the bonnet, we're talking about using the flow over the bonnet ( and thus an area of low pressure) to draw air out from under the bonnet and hence increase the pressure differential across the radiator and allow more heat to be removed from the turbo side via through flow. Those vents are pretty close to where I plan to do my cut'n'shut effort. Final design will be determined by the bonnet brace although I might be able to work around this for easthetics if I'm careful, clever and skilled...

[dest]

Its got nothing to do with where the engine is, its to do with how air goes over the car.
Have a read of the thread I linked earlier from Passionford, it is explained well on there

[Rusty]

My plans are to vent over and to the rear of the turbo and to the rear of the radiator.

[Rusty]

Should have a bonnet sorted from All Audi, need to get down there when I have the time and energy. It's going to get a coat of satin black so doesn't need to be in that good condition. Also going to have a look at the front strut on the rear idea that I've had in my head for a while... (better ARB pickups, cheaper replacement parts).

[Jamo]

Get anywhere with this Rusty? I have my own spare bonnet and wondering if I can get the duct thats pictured on the S1 turbo side?

[Rusty]

Nah, gave up as I wasn't well enough to do anything with it. I think that some vents after the radiator would be a good idea and some at the back by the scuttle pannel on the driver's side, help with cooling. Another option is some bonnet spacers like the Ford boys do, lift the rear of the bonnet up 20mm or so...

[fish]

http://www.blocket.se/halland/Audi_s...2.htm?ca=5&w=3 http://www.garaget.org/?car=134708 http://www.garaget.org/?car=18083 Here are a few ideas...

[Prophet_dlx]

I can show you the way it shouldn't be done:

previous oner drilled some holes into the bonnet and now I'll have to find a sollution to make it look better

[Jamo]

Cheers Fish



Anybody know where I can get this vent?

[Dobby84]

I am thinking about making some kind of bonnet vent above the air filter to allow more cold air into that area.
Maybe something like an S1 vent or similar cosworth style vent. Maybe just a slots cut with a mesh.

My concern is that in wet weather will water go through the vent, onto the filter and then into the engine?