[JeffR116]

I was watching rally TV the other day and talking with my friend. He's really into the WRC and I observed a distinct sound coming from some of the cars. He said it was the turbo wastegate dumping to the atmosphere. It definitely had a unique sound. Would not dumping it to the downpipe offer some serious advantages? I would think so. Someone shed some more light on this subject please.

 

[sakura-iro]

what advantages do you speak of?

most serious off road cars (dragsters and rally cars) run a "divorced" wastegate that goes to the atmosphere. there are two pipes coming off the turbo, one runs into the normal exhaust, and one runs directly from the wastegate of the turbo to the atmosphere. what you get is less turbulance in the exhaust. you might want to check out howstuffworks for questions like this.

 

[CloNeGTS]

As said above, there are absolutely no advantages to ever running the wastegate into the exhaust stream, but since the EPA says we must, we try to do it in the least intrusive manner. All it does is mess with the exhaust flow on the backside of the turbo, slowing the flow down and raising the pressure. That rise in pressure lowers the pressure gradient across the turbo, lowering boost.