Woah . . . sorry Bruce . . that was a direct (Copy Paste) from a post by "Richard Schubert" . . . must be another Long EZ builder . . here's the whole quote (Italics).
======================Cookedinlh===============================================================
Richard Schubert said:
Well, dynamic pressure is equal to 1/2 * the density of the fluid * the velocity squared.
Lets say 150 mph(thats indicated) 150*5280/3600= 220fps
Density of air = 0.002377 lbs/cuft (approx.:) )
so (0.002337)(220)(220)= 113lbs/sqft of pressure
divide by 144 for sqin =0.786 lbs/sqin
atmospheric pressure = 29.92 in mercury or 14.7lbs/sqin
2.03 in mercury/1psi
0.786*2.03= 1.6" max theoretical pressure gain
YMMV
"Just finished a fluids course and I couldn't resist":D
Thats a lot of numbers. On my IO360, 1.2 is about what I see on the manifold gauge when I switch from the filter to the direct ram air. Numbers aside the difference between the two on a sea level take off is worth every bit of the little drag of the scoop. the difference starts at about 150 mph and makes about a 500 ft./ min increase in climb rate. As to the drag issue, the air has to get to the engine somehow. even if it comes in with the cooling air into the cowling it is still creating drag. if some of the air goes for engine intake then that is air not used for cooling. the total of intake and cooling drag is the same weather it is in one scoop or two. why would you not take advantage of the higher pressure air and pipe it directly to the intake.
COWL AND WINGLET MODS: Finally got to check my cowl mods. The two exit scoops look very promising. You will notice that I have a fairly tight opening around the prop hub; I did this because I do not believe there is good exit flow around the hub of a pusher based on oil flow I have seen inside the cowl and other indications. Originally (2nd pic) , I believed I would get good exit flow from large openings around the exhaust pipes at the edges of the cowl but that did not seem to pan out.
The new exits allow air to blast out of the cylinders and return to freestream by the most direct route with the minimum turns and turbulence, I think. (pics 3,4). In addition I think I've added a few sq. inches of exit area.
Before, I was only getting about 4 to 4.5" of water differential across the cylinders. I am now seeing about 6" and 330 deg. at moderate cruise speeds. I will have to wait for a hot day for a full test. Manometer setup, pic 5. I added an adjustable door on the oil cooler. At current temps--about 55F--I have the door cracked a bit to get 180 degree oil temp. This oil cooler duct system is not the easiest to install but it seems to work well. (pic 6)