What are peoples thoughts on the variable fresh air duct (VFAD) on the high power renesis? I saw it for the first time the other day while the bumper was off installing my Hymee grill. In the picture below, it is the intake with the rectangular opening.

Below 7250 rpm, the VFAD is closed. Above 7250rpm with WOT, the VFAD opens up to introduce additional ram air to the air cleaner.

My question is - if more air will allow the engine to breathe better - what's the point of the VFAD? Wouldn't you get better performance at low rpm if it was open the entire time? And if that is the case, is there an easy way to make it stay open all the time, or better yet, remove all that crap forward of the air filter all together?

I thought it might have something to do with pressure wave tuning for the SDIAS etc etc, but I'm pretty sure all of this is done downstream of the filter.

Thoughts?

 

This answer question?
https://www.rx8club.com/rx-8-discussion-3/new-renesis-utilizes-helmholtz-tuning-5710/

 

Ouch! My head hurts after reading all that. Lots of good info there about intake tuning. Hats off to the guys with the 50 pound brains.

To quote rotarygod, here is the answer to my original question:

"If the 2nd intake port was always open then what I suspect would happen is that a little low and midrange power would be lost. Probably not much but we want all we can get. Alot of the 2nd gen RX-7 guys somehow think that leaving the auxillary engine ports open all the time gives them more power when all it does is to lose them some low/mid power and gas mileage. It's there for a reason and I wouldn't change its operation as long as it remains stock. If you change the entire air intake system to something else that is a different story."

 

****.. no more links like that please..

++dez;