What is the purpose of this system on honda engines?
This is also associated with the secondary runners in some intake manifolds... what is its fuction and do you need it?

I suspect it's for midrange torque... but still doesn't make sense why.

 

Its purpose is to vary the length of the intake runners. If the runners are short they will benefit the high end more. Long ones are good for low end torque. Look at a toyota truck's intake manifold. The runners are about 4 feet long before the damn engine. Torque is the reason, its a truck. The same goes for these Honda engines that are revving to hell and beyond. Its Hondas way of matching the intake to the cam.

 

ahhh thanks very much!