I invite you to the Bernulli Principle web site.
http://home.earthlink.net/~mmc1919/venturi.html I
did some shapes to play with in the attachment.
Leave the
reverse cone at the right end to replicate the port into the chamber. Note a
little yellow sign pop on when flow slows too fast and separates.
This would be at the bowl shape where the flow makes the 180
turn into the chamber. This area is too big volume wise and costs power. Some
racers fill this in slightly to eliminate this problem. The lack of this
feature in the periphery port engine makes a huge difference, in that velocity
is carried right into the chamber, rather than slowing.
Although
not practical the ideal shape is probably a long tapered runner. So velocity
rate of increase is a constant value.
Imagine that the mixture
is a sausage, and you want the biggest piece of sausage cut off by each rotor
face.
The highest possible velocity is important for that. However the
high velocity creates the highest drag over a long distance.
Two
44MM chokes in a Weber is enough for 310 HP at 10,300 RPM from a 12A. The TB
size need not be the runner size. My engine with a bridgeport gets 250 HP
at 9,400 RPM from two 38MM chokes.
Short runners for high RPM. Long runners for low RPM.
Big runners slow velocity and ruin low speed performance with big
thin pieces of sausage. Small runners give crisp low speed performance
with smaller, longer pieces of sausage.
Now you won't sleep
tonight either.
Lynn E. Hanover