Thread: Vents
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Old 08-11-2018, 01:44 PM   #2 (permalink)
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Originally Posted by Taylor95 View Post
Hi everyone,
I'm a new member and can't find much information here on this topic. I want to add hood vents to my vehicle solely for aerodynamic purposes. I know that by doing so, it will help decrease some lift in the front of my vehicle. Where would the best place to put hood vents be? For styling purposes, I am wanting to place them towards the back. I drive a 97 Keep Cherokee if that helps.

If anyone knows much about the effectiveness of venting the wheel wells as well, that information would be welcome.
*technically,you'd have to do either a professional CFD,or wind tunnel pressure profile analysis of the JEEP to locate the ideal extractor sites.
*and according to the experts,at normal, legal highway speeds,lift would never be an issue.
*The proximity of the radiator,cooling fan,and shroud to the engine,are going to make it very difficult to come up with enough clearance to create truly low-drag extractor ducting,either below, above,or to the sides of the radiator.
*The hood's underside reinforcement webbing will dictate where you could make a penetration without ruining the structural integrity of the panel.If you cut through the wrong place,the hood will 'fold' on you.
*For a 'guess',attach a bunch of woolen tufts to the hood,drive it above 20-mph,and photograph the pattern they make on a calm day.
*Where the tufts are squeezed the closest together,is where the air is moving the fastest,and pressure the lowest,making for the best extraction.
*Mark that area on top,then open the hood and see if there's a space below there,where there isn't bracing.If so,make your penetration there.
*Bear in mind that 'weather' is going to enter your new opening.You don't want water to flood electronics under there,so check that out.
*If you have clearance,you can attach ducting to the underside of the hood penetrations which will protect under-hood areas from unwanted wetness.
*And the ducting needs to be radius'd such that the air escaping the engine bay blends into the over-hood airflow otherwise you'll create separation and turbulence right there.
I had to do this on my truck.It took over 1-week for the fabrication.
*You might look at the 1978 Pininfarina CNR 'banana' car for it's cooling outlets.
*Also,the 1957 MG EX 181 land speed record car.
*Also,SAE/Shell Eco-Marathon racers.
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