I've just bought a 2006 Scion xB, and I've been looking at all the FI kits, home-built and other wise. And I just have one question. In the pursuit of higher performance what is the deal with the trend of using an archaic BOV set-up instead of a bypass valve. Now I know that if you had a carbureted set-up the BOV would be necessary due to that fact that any air flow past or around the carb would also cause fuel flow (venturi effect). On a Fuel injected car when the butterfly is closed and the car is coasting the computer shuts of fuel flow, making the bypass valve the way to go. Not only do you waste all of that pressurized air you cause you system to run rich and bog as a result. The air you are dumping out of your blow off valve has already been measured by your computer via your MASS so your computer is expecting that air and adds the fuel required. Unless I'm wrong and as soon as the butterfly snaps shut the computer stops fuel. I know this thread will most likely be attacked, but before you flame the bejesus out of me bear in mind that most of my forced induction experience is based on research, theory and a bad experience with a '98 New Beetle 1.8T (don't ask).

 

a lot... a lot of people just like the sound.