Engineering types..math / Venturi Q

Can anyone turn me on to the info of how to design a venturi with a ****erfly in it?
Do Hillborn units have venturies or are they just straight through?

 

It's the less-than-atmospheric pressure created below a venturi that draws the fuel out of the carburetor float bowl. It ****s, in other words.

A Hilborn blows the fuel under pressure through a sized nozzle to the port so no venturi is needed. It's a straight through bore. The throttle plates only determine the amount of air allowed into the engine.

 

Shouldn't be too difficult.

Just knock out a longer than normal venturi and stick a ****erfly & shaft in the straight section.

Although . . . I don't see the advantage here.
A ****erfly below the venturi works fine.

It may be interesting for you to take a look at a CV (Constant Velocity) carb.
They have a diaphragm controlled by differential air pressure that lifts the slide.
Downstream from the slide is a ****erfly connected to the throttle pedal/grip.

Pretty much impossible to over-carburate with a CV carb.
Crack the throttle ****erflies open at idle, the slide opens a touch and as air flow increases the slide opens further.


I thought you were going to ask about venturi area which was the way multi-carb setups were rated back in the day.
The CFM flow figures we use today are far better because they reflect the actual air flow involved.

JohnnyFasts answer is a good one although the fuel is "****ed" within the venturi's low pressure area and not below.
Which I'm pretty sure he knows.

 

Thanks, C9....but I didn't know.

I ran Hilborns on all my race cars over the years....carbs are new to me.

 

Okay, so the only reason for a venturi in a fuel injection system would be if you needed a pressure drop to measure flow?

So, I'm guessing then that the newer throttle bodies that have what looks like a venturi is really just a smooth way to transition from the larger air intake hose down to the throttle bore?

I'm just having this little flash back about convergent/divergent nozzles and laminar flow from a 'fluid flow' course I took about 22 years ago.

Maybe I need to dig through my old notebooks and do some homework.

Thanks guys.

 

stop! stop! the flashbacks! little bugs crawling all over me! stop!

 

Although slightly o/t this is a good read about CFM Ratings on Carbs:
http://hotroddersauctions.com/cgi-bin/racing_forums/ikonboard.cgi?act=ST;f=7;t=1

 

You just made Cheerios come out my nose you *******.

 

hey, I sat thru fluid mechanics in the early 80s too....