Vlad,

 I was throwing out some old books in the hangar and I ran across this
 Holley book published in 1976. Nothing new under the sun.

 Paul Lamar

 "Independent-runner Manifolds-"

 "Independent- or isolated-runner (IR) manifolds
 are race-only devices with one carburetor throat and one manifold runner
 per cylinder-head inlet port."

 "Carburetors used in IR systems must be much larger than for other
 manifold types because each cylinder is fed by just one carburetor
 throat or barrel. Another reason for needing a larger carburetor is
 the severe pulsing in such systems reduces carburetor flow capacity
 in the RPM range where standoff becomes severe. In any IR system,
 some method of standoff containment should be used."

 "Plenum-ram Manifold-"

 "This "almost-IR" manifold uses a plenum chamber between the carburetor
 base and manifold runners.  This chamber helps to dissipate the strong
 pulsing
 so less of it enters the carburetor to disrupt flow. Just as important, it
 allows the cylinders to share carburetor flow capacity. In the typical
 dual-quad
 plenum manifold, three or four cylinders are simultaneously drawing mixture
 from
 a plenum being fed by eight carburetor bores.  The sharing of carburetor
 capacity
 allows the plenum-ram approach to manifolding to be "very forgiving" in
 terms of
 carburetor capacity so long as the carburetors are not too large for the
 RPM range to be used."

 -----------------------------------------------------------------------
 Another interesting chart from the book.
 This is based on 12.5:1 mixture and a BSFC of .6 which is still pretty
 valid
 for todays engines at full power. I added the stuff in red. The 160 cubic
 inch 13B is rated at 200 cubic inches in p-port form because the VE is
 %120.
 The 13B fuel burn will go down to about .47 BSFC when leaned to 18:1
 at cruise around 6000 RPM.

 Paul Lamar

Learn something new everyday. If I understand those exerts correctly,a
"plenum ram" manifold would be more beneficial for our application than a
"IR" manifold. Guess I'll try to make some renderings of a "plenum ram"
manifold when I'm finished being lazy. Thanks for the rotary and Holley
files, I'll work on making the Holley more "realistic" when I've overcome my
laziness.
Vlad


Last time I am going to send you any solid models you lazy sot :)
OK I did it myself. I also enlarged the plenum on a couple
of Holley manifolds to see if I had room for it. Any intake
system you do needs to fit under the cowl.

Paul Lamar