Quote:
Originally Posted by speedracing944
Why it is true the AFR stays the same (I am not debating that) the pumping efficiency decreases. This in turn decreases the thermodynamic efficiency which in turn decreases the efficiency of the engine (mass flow being equal for "dirty" filter vs. "clean" filter)
Take a garden hose and suck on one end of it while the other end is free of obstruction. Then take your sock, coat it with dirt and mud, tie it on the end of the garden hose and suck on the free end. You will have to "work" harder sucking on the garden hose in scenario II to get the same amount of mass flow. The increased "work" or energy exerted for the same effect will reduce your "sucking" efficiency.
Oh boy this is getting too detailed 
Speedy |
If the filter is causing restriction at a given throttle position the throttle plate simply opens and negates it. This of course can't happen at WOT which is why maximum potential IS affected.
Take your garden hose example, you error is in assuming there is only one restriction (the sock). The reality is that there would be another valve right by your mouth. Without the sock on the other end you may be able to suck Xcuft of air per second with the mouth valve open 10%. But...with the sock on the other end you need to open the mouth valve to 30% to have the same restriction free flow of Xcuft per second.
Make sense?