I suppose this is really aimed at Stuart Firstly is it a realistic possiblity to make a bond in panel for the bonnet to achive this Then the big question would you consider it (where IS the begging icon )

If i ask the other other Tim very very nicely maybe he will post the relavent part of the picture which would explain more than i could in a thousand words

This should be a piece of p*ss.

There will be somewhere on t'internet the relative dims for a naca duct. Carve the buck out of pearl board. paint it. Put it on a piece of glass and grp over it. Dead easy.

How big do you want it? I have templates for 6", 8", 10" and 12" wide Naca ducts.

It would need to be more of an escape for the air from the radiator, because the air struggles to get out of the bonnet.

I could drag a picture out, but it's like what you have on an elise.

Its not to hard to do, but you could always cut the front section with a "U" shape, push inwards on the lower part of the "U" on the front section, template the side (triangular voids) allowing for clearence of the fuel tank ect. Use a triagular section to hold in the cut "U" section   thus creating a exit duct to your own size and shape 

Maybe that's what they were for!

In the boot of my Coupe when I collected it were a pair of Astra GTE bonnet vents. These are very similar to the NACA duct but designed to fasten into a suitable size hole. I'll have to have a closer look and see if I want to use them or not.

I've also got a pair of Metro (Rover) GTi bonnet vents that are designed to do similar - fasten into a hole in a panel that is. If anyone wants them they are welcome to come and get them.

Iain

IIRC Naca ducts were developed to produce minimal air turbulece while still allowing passage of air thru the aperture. Useful on the front bonnet, but doubtful on the engine cover. Raised vents would be better on the rear cover to stop water getting through onto the engine.

What Pantera says! NACA ducts really only work well in a clean air flow. I don't think they would do much good venting air from inside an enclosed and disturbed space.

I thought that's what the two Tims were talking about - a vent in the bonnet to get rid of the air that has passed through the radiator.

Iain

Definitely what I was taking about I'd was what the other Tim was on about too. I think it would be one of the better mods on the body work to help with air flow through the radiator. It would be good to have a mould that you could use to adapt existing bonnets.

I've got a simpler fix for this.

If you were to chop out and change a portion of the bulkhead just below the windscreen - obviously either side of the wiper, you could get it venting yet hardly be seen.

I'll firtle a piccy when I get chance.

As Tim Rowe said that's what i hope to achieve, not just let the air escape but help draw it through as i,ll have 2 rads to contend with A bond in panel would be brill The outlet needs to be between the rads and the fuel tank.

Is my idea of no use to you Tim ? ?

Only potential problem is the exit is next to the screen which will be at a higher pressure than an exit on the top of the bonnet and suspect will have a large boundary layer built up there due to the change in direction so will not be quite as efficient. As air likes to flow from high to low pressure zones,

Suarts idea is very simple and could easily be implemented.

WEST

What you need is something like was on the Davrian bonnets, as Stuart said.

Will look for a pic and add later.