Pressure isn't "built up" You have a stagnant pressure zone at the hood and windshield. Even a simplified understanding of Bernoulli would tell you that the air pressure of the air moving under the car is lower than that sitting at the cowl, drawing air into the engine compartment.
Here my proof, on a 1970 Chevelle with cowl induction there is a latch that opens when there is enough pressure at the cowl to allow more air to flow in professor.
It isn't velocity pressure genious....it's stagnant pressure..... and it works entirely different than the idea of "Ram Air". I'd hardly call that "proof". Have you ever stuck your hand out the window on the highway? You do realise that the force pulling your hand back is almost entirely drag right?
Yet the air in the bag is stagnant....except for vortexs formed at the mouth...which is why it remains inflated as the air around it passes. There's a reason most vehicle intakes are off to the side behind the headlamps or directly on top of the engine. The air is very close to stagnant in those places....although warmer. If you measure the pressure inside the bag, you would find it is identical to stagnant air pressure say, inside your house. It's why Pitot tubes are innacurate at very low velocities. Like I said....you don't understand the fluid dynamics involved. If you want to do that experiment correctly, put some small holes in the rear of the bag, then measure the wind velocity in an uneffected region....and the wind velocity streaming from the holes in the bag. You would find they are identical.
The mechanics behind Fluid dynamics is far from opinion. I'm not the Catholic church....I'm Galileo.....
That is the most retarded thing I have ever heard. This is why you are in shop class as opposed to physics class.
People are silly and never listen. Put a hole at the end of the bag and air flows through. An engine is not a closed system. Air is being drawn in and the ram air just means that the engine doesn;t have to work as hard to draw the air in, that is it, plain and simple. Why can people not get that.
No ive taken physics, but shop is just to get experience about how diesel engines work, and it cant hurt now can it? Dont make fun of someone taking a shop class. thats is the most obsurd thing ive heard. And If I take welding are u gonna laugh at me as well??
High school physics wouldn't help much in this situation. For one, its much to oversimplified. and two, this is mostly a fluid dynamics issue. Which is a portion of physics, but isn't taught in any detail in high school.