Gurney Flap Across the Bonnet/Hood

[260DET]

On the 280ZX I have fixed flaps about 25mm/1" high across in front of the two OE vents, plus have blocked off the OE NASA duct, in order to improve air extraction. Air hits the flap and is deflected up over the vent creating a low pressure area behind the flap. Then I realised such flaps would provide some downforce which led me to think that a long flap right across the bonnet/hood, say 150mm/6" back from the front, would provide more downforce. It would also create turbulence in that area which would further reduce lift.

 

Can't remember ever seeing this done, perhaps the extra drag may be considered as too much of a penalty. But my motto is, 'more power will fix most things' so.........

[JMortensen]

I think there is a reason you don't see this. Turbulence is still not high pressure, it's low pressure. It's just not efficient low pressure. It's drag. So you'd probably create a bunch of drag and very little downforce. The reason it's worthwhile on the hood vents is because the pressure change on top of the vent reduces the pressure under the entire surface of the hood, and a slight pressure change under the hood multiplied out by the surface area of the hood can have a very large effect on overall downforce.

 

I'd put a bigger splitter on or bigger vents in the hood, etc before trying to put a spoiler on the hood (which it seems is basically what you're talking about doing).