Originally Posted by yyz
This really confuses me, the necessity to open up the air box. I have a 2011 Ford F150 with a 5.0 liter V8. The engine breathes thru a tiny 3 inch plastic pipe. If that motor could run fine with such a small opening, why would a 250 cc engine need almost as much air flow?
Maybe I am missing something.
A single cylinder sucks in a glob of air ever other revolution of the engine...in other words the flow stops and starts repeatedly. The more cylinders you get, the closer the flow gets to steady flow. When you get closer to steady flow, the resistance to flow drops because you have established a flow pattern....and you don't have to waste time and energy reestablishing the flow pattern (scientists call it a "flow field") over and over again.