Ram Air intakes
Cold air intakes or ram intakes
One of the very first mods to do on a performance car.
When you buy a performance car you want to hear it right?
Manufactures design and build intakes to fit snugly, packaged neatly and to support the intended power levels and noise levels. Most are just put together from parts in the vehicle range, with the small alteration here and there to acomodate sensors or what ever.
Take the Fiesta range, you will see the same airbox on most of these cars, being 1.0 Eco boost 1.4 N/A and even the ST. Focus Range is the same. Take the MK2 RS, its got the same box as the 1.6 Focus with a small pipe added. Then it reappear in the ST250 range.
Now enough about that.
Why do you need an Intake? short answer is, FLOW!
The intake of a car opens to atmospheric pressure. at sea level it will be 14.6 psi positive pressure. Now if the flow into the engine is constricted it might loose some of that free pressure. So in fact you are loosing free power.
Even worse on an turbo car that will suck twice as much . More flow more loss due to pressure drop.
So we see that even on an Intake there can be pressure drop due to Irregular shapes and flow constrictions and filter materials. So the coal is to make it flow better