Acoustic valve

Contrary to what everyone on here thinks it’ll actually hurt performance. The valve is there for a very good reason.

in gears 1,2,3 the ecu will enable the solenoid so the valve can open, this is to maximise airflow going into the airbox. In the gears above that it remains shut to use the ram-air effect for maximum filling at higher speeds.
  • Like
Reactions: Dutch_197


Paid Member
Does anyone know what position this should be in at idle when in gear? I've put the standard air box back and connected all the hoses but it stays open. :think:


Paid Member
Sorry to bring an old thread back :oops:

I have a 200 but the tube to the throttle body is blanked off with a rubber bung from the car having had a KTR induction kit, and the acoustic valve has the tube that connects between them missing. What parts are required to connect this up as the tube appears to have a non return valve or similar but I can't find it on parts breakdowns of the 200 that are online?
Does this have any real effect on the way the car runs such as the 2-2.5k flat spot or when warming up from cold start when it can kangaroo?


Paid Member
Correct, in lower gears or RPM the engine benefits from longer intake trajectory to get better torque.
Honda had this on B18c4 engine like found in the 1.8 VTi but then used in the intake manifold itself.