I think you're a little lost on that one. It DOES NOT go back out through the air filter. There is a reason that the air is recirculated on AFM and MAF cars. That air is already accounted for, so it can't just be dumped or a rich condition ensues. It must be reintroduced to the intake tract AFTER the AFM/MAF so it can be reintroduced back through the meter without being reaccounted for. If the point was for it to go back out the filter then it would be vented before the air meter and not after it. So in case you dont really know, it doesn't go right back out the intake. And there are manufacturers such as Porsche who have used recirculation to actually keep turbo wheels speeds constant by recirculating the air in such a way that its directed right through the compressor inlet with special plumbing. Now answer me this: If this was such a waste of money and so useless why would companies be putting these things on there vehicles. I'm sure Porsche has better things to do with it's money then add useless parts to their highly touted machinary.

And as for proper WOT shifting: It has no place on a street car. It's going to do one (or both) of two things: Either you're going to engage the clutch too hard and shock the driveline which will eventually lead to fatigue. Or you're going to ease the clutch in, waste time, and burn off excess disc material. A car built for the track can handle this abuse and is usually torn down to have parts replaced. Since we're on the topic of wasting money, I'd consider clutch abuse a waste of money. Cause no matter how high you keep the engine revving, the transmission speed is going to drop between shifts. So unless you shift REALLY slow, there is no need to power shift on anything less than a race track. And even then it's not always the best idea. Especially on the stock driveline.

And surge has just as much effect on the thrust bearing as it does on the vains. If not more so. What do think cause thrust bearing failure? Excessive loading. Where does that load come from? From the air surging back against the impeller from the closed throttle. The impeller is already being pushed in one direction, then that surge air hits it and forces it back in the other direction. That constant rocking back and forth is what wears the thrust bearing out. That is another part of where the BOV comes into play.

Call it rice all you want. It's an important part of the turbo system. Again, do you NEED one? NO. But it's a good investment. Not a waste of money.

 

How can pressurized air stay in the intake when there is an open hole for it to escape from? Not all of it, but some of it will go back out the intake. And now, since air isn't coming in, it's got to go out. There's the problem with BOVs and MAFs. They register air travelling by the wire. But they don't know what direction it's going.
I can't. I didn't realize Porsche uses BOVs on their cars. But you're talking about a 3.6L flat-6 that makes 400+hp from the factory.

 

Hey guys sorry to start this all off my bad....

Thanks to some for helping and im glad he got the information he wanted. It took a little spark to get the gas ignited though! Glad to see you guys do know what your talking about though.

Turbo cars are not knew to me. It was my bro's conquest so i worked on it alot and I put a turbo on bmw 325is also so i know a little bit! But thanks for crushing the noob.

Keep up the good work guys