Imidazole

VFAD (Variable Fresh Air Duct)

I heard that our 6-speed 8's have this. All I know is it allows more air at higher rpms. Could it be a good performance mod to enable this at lower rpms? Where is this? Does anyone have any details on this? Does this explain the sudden kick in the last 2k-3k rpms?

robertdot

Read RotaryGod's Post in this post and you'll see that the VFAD is tuned specifically for our intake system. If you want to tune the VFAD differently, you need to change the entire intake system to get good gains.

olddragger

iTrader: (3)

Guys,
That is what Racing Beat is doing with their new airbox (when it comes out). The major change from stock is enlarging that intake area. Ive done a lot of work on my stock system and in my opion it has turned out better than any aftermarket one. Do a search on custom airboxs.
olddragger

rotarygod

By just opening the VFAD duct full time, you aren't gaining any low end. I drove brillo's car around this way for a while and it feels a little slower. Removing it entirely and redoing this with a new one could give more power. Just opening the duct earlier won't do it though.

robertdot

I saw their box. I couldn't remember if it had a replacement tube from the intake manifold or if it was just the box replacement. And, I wasn't sure if the fact that they didn't modify the intake manifold would, in the end, have changed that much on the tuning (i.e. not the entire pipe is bigger, just the first part of it) or the HP (it apparently only adds about +3, so...).

Last I heard, RB wasn't replacing or removing the VFAD... they replaced the airbox (and apparently the tube to the manifold). If they finally decided to, I stand corrected.

rx8wannahave

Ditto, is RB doing this? That would be great...you got to give it to RB, they are the rotary experts out in the rotary world. I hope to be a customer becaue I like how they do things over there, cept for the price on some stuff.

If they modified the airbox/VFAD system and gained some significant HP per $, I would be at their door the next day...LOL

Mr M

You can have the VFAD permanently open by disconnecting the VFAD solenoid connector. The VFAD solenoid is the one attached to the aircleaner box.

(The solenoid provides vacuum to the valve at low rpm, to keep it closed. When the solenoid comes on atmospheric pressure is fed to the valve, allowing it to open)

MyRxBad

iTrader: (1)

The intake is the perfect length and is engineered to take advantage of the HemHoltz (sp?) effect of supercharging. Do a search on Hemholtz here or on the net.

Charles R. Hill

iTrader: (7)

Helmholtz resonance.

CRH

MyRxBad

iTrader: (1)

Thx for the corretion.

Charles R. Hill

iTrader: (7)

correction. LOL.

CRH