V6 Inlet Manifold- Vis Valves - How Does This Work?
 

Hi all,
I have been reading this from the Rave CD-

http://i744.photobucket.com/albums/x...ps6a9a0a5d.jpg

http://i744.photobucket.com/albums/x...ps142ab377.jpg

You can see from the above how the vis system is layed out.
Intake air enters into 2 plenum chambers after the throttle body, at the end of each plenum there is a balance valve to either join the two plenums together or seal the plenums independently so each plenum feeds 3 cylinders each. There is six inlet pipes which feed from plenums to cylinders, these each have a valve which is opened by the power vis motor. These open into a apparently sealed 3rd plenum with no apparent in or out other than the power valves.

So at low speed each cylinder pulls through a long tract and plenum.
At mid speed each cylinder pulls through a long tract and both main plenums.
High speed- all power valves open so each cylinder pulls through the short tract plenum but as the power valves open into a sealed plenum the air must be being pulled through the other open power valves/ long tracts and main plenums.

Can someone explain this- the power valves open into the 'short tract' sealed plenum which gets its air from the long tracts/ main plenum so how can it be shorter??

I have racked my brains over how this works

Note the words "tuned to resonate", must be like a musical instrument when it all comes together. Read Wikipedia "Inlet manifold" and Helmholtz effect

It's always a good idea to find out how things work! ;) Unfortunately, MG Rover's technical description is unreliable. Take the very first sentence:

"At low speed the balance valve and power valves are closed"

Errr ... actually the balance valve is open. If you don't believe this, ask Stocktake.

So Simon, don't torture yourself. Unless you know someone highly qualified in the fluid dynamics of internal combustion engine intake systems, it's best to just make sure that the system is working as designed. :D

Simon

Hi Simon,
I think reading the description on how it works confused me more.

If both actuators are working, the inlet is working as it should. It's a bit of a grey area to describe what actually happens, but Rave seem to have their own idea on the subject.