Intake "flapper"

[ZachPDX]

I was searching for something else and came across this post at AW

"Airbox modification - 2005 model. Sounds better!"

I have a 05 and never heard about this before, is this pretty common? to keep the flapper open all the time and block the resonator?

[ChronicTeutonic]

That flap opens above 5000 rpm or speeds higher than 200 kph (~100mph) to let more air into the filter box. Audi calls it the Power Flap...

[V8S4Fun]

Nice diagram, I see the flap that they are talking about keeping open, but where is the resonator that they are blocking?

[EssPhore]

Has anybody tried this? If so, is it a worthy mod?


Sean

[Stormin]

It would seem (to a psychology major, with no background in mechanical engineering) that the flapper going away would be a good thing at all times. A bit louder, but hey, nobody here should be the type to fuss about "a bit louder."

[Fermiumhalo]

This is the same sorta thing the Vtec Integra GSR engines have. There is a Secondary Butterfly setup in the actual Intake manifold. I wanna say the theory for this has to do with air velocity. I'm sure Audi didnt really care about noise when drawing the S4's airway. Regardless this would be a great mod to test while on a Dyno being as it seems fast enough to do. Anyone getting dyno'd soon wanna try this and report back? I wanna say you may loose power... then again it may end up allowing cooler air in from that front vent. Now I'm curious :)

[Stormin]

LOL. VTEC engines engage an entirely different cam profile using secondary lobes actuated by oil pressure...

I may be a psych major, but I went through school driving a 2001 Prelude that had been modded for track days.

[Fermiumhalo]

LOL. VTEC engines engage an entirely different cam profile using secondary lobes actuated by oil pressure...

I may be a psych major, but I went through school driving a 2001 Prelude that had been modded for track days.

Yes I know that Vtec activates that way but the OBDII GSR engines use a secondary flapper system in the Air intakes. basically uses only half the manifold and then at 5300 RPM the butterfly opens the bottom intake runners allowing more air into the cylinders.

[Stormin]

Ah...

A feature not present on the Prelude, which had just the regular 4 runners. (Though my factory intake manifold lasted all of 14 days before being pulled when the new one arrived, so it would not have mattered.) That had to be an emissions/fuel economy issue?

[GFRRS3]

So did any one do this yet and is there any difference in sound or throttle response????

[WinterRunner]

What about the exhaust flapper? I'm curious to know about that too....

[S-Fore]

I took mine out when I installed my Carbonino, and when I went back to the stock air box I just left it out. Cant say that I really noticed anything. Would there really be anything to notice?? except a bit of noise.

[Justincredible]

I did this the first few weeks I owned the car. I posted this on A/W
http://forums.audiworld.com/s4b6/msgs/434430.phtml The A/Wers don't seem to be as mod friendly thinking out side of the box some times. The post had mixed reviews.

I did test this with Vag Com the result was more a higher MAF value across the board. Was there a difference in power...not really I think the MAF value is good to show the car is getting in more air. But with a stock chip the car is only going to do so much with the extra air.

ChronicTeutonic chimed in and as in this thread was super helpful. Stating that the car " Audi Training Manual states that the flap opens around 5k rpm on the RS4 to increase airflow " I found this to be true as I Vac tested the line.

My 02. on this
We have seen from several people that the stock air box dose quite well for the B6. Audi seems to think that above 5k the box might need some help. So there might be some benefit in having it open all the time. But most likely the benefit will come in above 4k when you are almost out of the Tq range as it is.

[ChronicTeutonic]

Justincredible thanks for doing the tests and letting us know your findings. I forgot to reply back to you on the Audi Factory stuff. It's all available through Robert Bentley's (makers of the Bentley Manuals for a bunch cars) website. I use the eBahn service which includes TSBs and campaign information plus the regular repair materials.

[Justincredible]

Justincredible thanks for doing the tests and letting us know your findings. I forgot to reply back to you on the Audi Factory stuff. It's all available through Robert Bentley's (makers of the Bentley Manuals for a bunch cars) website. I use the eBahn service which includes TSBs and campaign information plus the regular repair materials.

Thanks you always have such good info on this. I wanted to ask you again but didn't want to be a pest. Thanks for the info I'm going to order the stuff tonight