Airbox flap

[rs4head]

a lot is said about the 5500 rpm "kick". is this as a result of the flap opening in the airbox and allowing the engine to breathe more freely? and can this be disconnected the same as the exhaust valves to improve performance/induction noise?

NEW OWNER - RS4 PHANTOM BLACK SALOON

[R7ANO]

The flap has nothing to do with the kick at 55 it's the throttle opening 100%,
which it doesn't do untill then even if your foot is on the floor!
If you open it all the time you will draw warm air into the airbox which is not good.
Leave it alone if it works!

[P_G]

It's a combination of airbox lap and 100% open throttle /restrictor switching of at 5500rpm.

[rs4head]

cheers guys. can't believe engine won't allow full throttle until 5500rpm - esp in a 4wd car!

[aidanjaye]

cheers guys. can't believe engine won't allow full throttle until 5500rpm - esp in a 4wd car!

Could be wrong, but think its limited in 1st and 2nd gear only- hence why the kick is more pronounced in 3rd.

[PetrolDave]

cheers guys. can't believe engine won't allow full throttle until 5500rpm - esp in a 4wd car!

It's not to do with 4WD or not, it's to avoid the torque in the lower gears exceeding the capacity of the gearbox.

[RS4POWER]

The tq limiter engages in 1-3 gear. You feel the kick because the throttle valve angle goes from 66% to 100% at 5.5k rpm. The air box flap opens at 5250rpms to provide the additional air necessary.

Most after market flashes remove this limiter and you do not feel a kick anymore. The that is because the throttle valve is open 100% way before 5.5k (not sure where each set it). In the winter I would think that removing the flap will help especially if the tq limiter is removed. If the flash can also decrease knock sensitivity due to high iat's then you have a winner. Perhaps MRC has done this and can chime in with thoughts?

[neckarsulm]

If the flash can also decrease knock sensitivity due to high iat's then you have a winner.

Isn't that safety measure there for a reason?