[speedracing944]

Originally Posted by lendaddy

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?

You know I thought about that as I was driving in to school this morning. The dirty filter is just another "valve" like the throttle plate.

The dirty filter would hinder the WOT max HP unless the filter area is so large that even with having it packed with crap it still is able to flow enough air to satisfy the requirements of the engine.

There is also the issue of once a filter is loaded up and the pressure differential increases across the surface there can be damage to the medium which would pull dirt through the filter which would otherwise not be able to travel through if the filter was clean.

IMO a dirty filter will NOT increase fuel mileage except to limit WOT max HP. It is better to run a clean filter and just place a block of wood behind the accelerator pedal for the same effect.

Speedy