I'll bet that this has been tried before (hard to come up
with truly original ideas), but has anyone heard of using a
'plug' in the end of the intake bellmouth as a throttle?
What I'm seeing is something shaped like an oven baster,
with the pointy end into the bellmouth. If it has an inside
radius which follows the bellmouth shape of the intake,
couldn't you have throttle action without the turbulence of
a butterfly valve (or slide at part-throttle)? I can see a
few design issues, like complexity, having enough force
available to overcome the vacuum as you try to 'open' the
throttle, & designing for 'fail open' instead of 'fail
closed,' but for the moment I'm just interested in the air
flow issue. I'm also assuming that throttle response & idle
characteristics won't be problems due to using electronic
injection.

Somebody shoot this full of holes. I can take it.

Charlie England

I can see it working in several areas. There are two problems that might be helped with this lashup. One would be the limit space above an air horn inside an air cleaner housing. If the bell shaped horn it too close to a flat surface, say less than one diameter of the intake runner, then when the cylinder pulls on that runner a lot of energy is installed by spinning the inlet air. This tends to choke off the inlet and make it flow as though it is smaller in diameter. When measuring velocities away from the walls of the inlet, I find that the very best flow is straight down the center of the inlet. I think, and may be able to prove that such a device might improve flow when fixed on the cover of a filter housing across from each inlet horn. This same shape then could be forced into the horn by a tiny hydraulic cylinder connected to the throttle with a stiff spring inside the cylinder to drive it open. Where along the bell it touches (what diameter) determines the loading. Or, if you
take that another step, make the horn and a bit of the runner slide up against the cover, to close the throttle. I suspect that in many applications there should be a set of thin sheet blades inside the inlet horn to prevent this unwanted rotation. Another job for Mr. flow bench.
Lynn E. Hanover

 
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