If, as many of the posts here posit, the V12 can be considered two 6 cylinders joined at a common crank; what is the purpose of the balance pipe at the rear of the engine?

Given the small but real differences in ignition firing and fuel injection timing between the banks, what good does it do to share a vacuum between the two intake plenums?

 

I would have said it was to allow the far bank to idle when cold (Auxiliary air valve sharing)

May be other reasons too?

 

Correct. Also to ensure in the event of a throttle or intake air problem on one side, the engine remains equally supplied with air. It also provides two vacuum sources for the brake servo and the ECU.

 

Both of those make sense. I guess I would have expected something more along the lines of a plenum as I have on my S600 Mercedes.

 

I've seen it in some multiple carburetor equipped machines. OEM or after market.

A means of balancing the intake pulses... Smoother running engines.

Carl