Hi
Found this, and it looks as if I remebered correctly about the theory!. Not sure about photos, it might be very difficult to get anyway near it... I will have a look soon.
Intake manifold
General
The intake manifold is used to distribute air to each cylinder. Mounted on the intake manifold is the throttle body, EGR valve, swirl valve and actuator motor for the swirl valve.
The intake manifold comprises a plenum chamber and eight inlet passages to the cylinder head, two for each cylinder. The inlet passages are designed to guide the air from the plenum chamber in the cylinder head inlet ducts. The cylinder head ducts are designed to provide a good filling factor and good swirl and tumble formation. A strong swirl motion is especially advantageous under light engine loads to attain a good mixture of air and injected fuel. One of the inlet ducts to each cylinder is designed to give the air a spiral motion as it passes into the cylinder. The shape of the other duct means the air enters at a steeper angle and with less spiral, called tumble. In order to obtain this form of tumble for every possible operating condition, the engine intake manifold has a throttle valve in each tumble duct operated by an actuator motor.
Function for light load, low to medium rpm
For driving under light loads, a strong turbulence is aspired to during the induction stroke in order to ensure a good mixture of air and fuel. This is difficult to achieve, however, as the mass air flow through the engine at this stage is only moderate. The solution is to increase the swirl action through external influence. By allowing the air to flow in only through the inlet duct giving the strongest swirl and blocking the other, a strong turbulence can be achieved also in this case. The tumble inlet duct is now blocked by the valve. Somewhat misleadingly, these valves are called "swirl valves" despite being situated in the tumble duct.
Function for high load, medium to high rpm
When driving with high output, the restriction of intake air would be too great if only one inlet duct was open. Therefore, the swirl valve will open so that the cylinder is supplied with air from both inlet ducts. The result is a considerable increase in fill factor of the cylinder so that the ECM can add more fuel without increasing emissions. The swirl throttle can be opened continuously so that the balance of tumble and swirl can also be controlled continuously. This is to obtain as good a mixture of fuel and air as possible.
Fergy