On the subject of Legacy Induction, here's my swing at it and why.  I don't see how the Ram Tube can add manifold pressure when the K & N Filter is vented to cowl pressure between the Ram Air Inlet and Engine Intake.  The manifold pressure increase when the butterfly is open to ram air would seem to be due to the small K & N Filter causing a restriction when alternate air is selected. 

 

The K & N I used has several times larger area than K & N's formula requires.  If pressure in the upper cowl is uniform (based on piccolo tube tests an engineer friend ran on his RV Plenum I believe it is) then I should get close to the same manifold pressure as Lancair's ram air with my design, maybe better.

Potential problems?  I do not have an alternate air provision but the proximity of the back of the K & N to the cylinder should cause radiant heat to keep that part of the filter free of ice or snow (neither of which I intend to fly in longer than it takes to reverse course).  I plan to put a temp probe on both sides of the filter to check.  Ok, if I have enough heat to prevent ice, will that heat induction air enough to significantly reduce MP?  Tests will tell the story.  Modifications may change the design completely.  Stay tuned for results, the plane is in the Paint Shop.

 

 

 

Steve Colwell   Legacy N15SC