[WardL]

I think there is enough flow through the side vents to prevent any "air pressure" from building under the hood. If the hood lifted with speed, I would speculate it could be the result of low pressure on top of the hood pulling up in combo with the scoop channeling air down through the engine out to the side vents. If your hood flew off because you forgot to lock it down, I expect you won't do that again! Seems like the side vents would let more air out than would flow through the radiator. I'm sure the front cowling will allow a lot more air into the radiator than the radiator will allow to flow through. That is one of the reasons the Cobra has such a high drag coefficient and referred to as an aerodynamic brick.