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Message: <blockquote data-quote="ReplicaR" data-source="post: 902748" data-attributes="member: 9209">I've never said that you need to push the air through the front of the car to make the heat extractor work. What I've said, is that the most efficient way to channel the air through the radiator is to have it in a sealed tunnel. It will pick up air in front, pass it through the radiator, and then dispose of it somewhere in a nice open space, preferably over the car. Another thing I did not say is that the opening does not expel the heat. I've said that at speed, it will suck the air in because it's a high pressure zone. When you are standing still, there are no pressure, because there is no air moving over the car. This way any hole will expel heat. Hell, no hood at all will be the best way to expel heat, right?It is very hard to point to one simple fact, and say that this is what's mainly causing the effect. Just like anything else automotive, proper cooling is a combination of things, such as air flow, heat exchange efficiency, pressure zones. You have referred to Venturi effect, which if I remember correctly has to so with speed of air and amount of pressure it will generate. I may have not referred to it as such, but I've talked about pressure zones for a very long while now. I will explain it again, using visual aid this time.<img src="http://www.tenlinks.com/news/PR/intelligent_light/gfx/092109_fieldview122.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />Above is a picture of pressures generated by wind tunnel testing on a C6R. As you can see the bits of the car which face the most against air are the ones which generate the highest pressure. The highest ones are on the very front of the vehicle and the cowl section, where the flow angle changes dramatically. The green parts are the ones with the lower pressure. Now, according to the Venturi effect that you have brought up, higher pressure will push the air into the zones with lower pressure. What this means is that at speed the air that hits the cowl will be in a high pressure zone. The raised part of the hood would generate a low pressure right behind it. Air will go anywhere and everywhere it could possibly fill. So, you've got high pressure zone right at the cowl, and a low pressure zone right behind the opening of the hood. Guess where some of that airflow is going to go?I'm not going to bother trying to explain this any further. There are tons of online articles which explain how the aero works, and why the heat extractors are place where they are. If you don't want to believe me, you are free to do whatever you want. It's a free country, so you can go ahead cut up the hood in the back, or run with no hood at all, because more is better right?</blockquote>