Why is this part here? 3bii air intake

[shansen]

Trying figure out what the function on this part is, Planning on adding a turbo in the next few months to my 1990 BJ75, 3bii engine. Recently when installing rebuilt injectors, I had the air intake elbow off and now I'm curious what function this flap serves.

From what I can see when throttle is pulled, the cable turns both a lever that opens up the air intake; further down the mechanical assembly it pulls a lever that calls for more fuel from the injection pump. I've highlighted in yellow along side the mechanical parts that move together when the throttle cable is pulled.

What purpose does the flap in the air intake serve? It opens airflow as the throttle is opened, but why restrict airflow? When a turbo is added, will the flap need to be removed?

 

[AirheadNut]

The 2L-TE has a butterfly valve also, it’s for the EGR system. Unless I’m mistaken the 3B doesn’t have an EGR system, so my guess is that it would be an anti-shudder flap for shutdown. I see no reason it couldn’t be removed, you’ll see a definite increase in off the line torque. The best way would be to take off the intake riser, drill out the two screws (they’re peened over on the backside) and pull the plate out.

 

[Tonito]

I am also running a 3B II and removed the "disc" part of the butterfly valve and it did not affect the engine at all. I kept the shaft to keep the housing airtight.