Why when you vent your wastegate into the open atmosphere is it bad? I know this is a stupid newb question but hey...i dont have turbo.

Performance wise, no.
Emissions wise, yes.

Another aspect to keep in mind: an open discharge is a 1500 degree, six PSI or more blowtorch at wide open throttle. If you run an open discharge, keep all flammable items out of the path of its wrath!

Due to engine compartment fires, many of the racing organizations have enacted rules against open discharges. They require that a wastegate discharge be routed back into the main exhaust. As this is a reasonable and quite sane rule, I suspect it will only become more widespread with time.

Boost It!
Bill Hahn Jr.

It is safe as long as you have a dump tube which routes the exhaust and flames down to the pavement. Yes, flames }> Looks pretty cool, and REALLY loud.

>Due to engine compartment fires, many of the racing
>organizations have enacted rules against open discharges.
>They require that a wastegate discharge be routed back into
>the main exhaust>

Must not have reach professional import racing. Nearly every FWD I've seen has a side or rear exit open dump tube right along side the main exhuast (routed outside the engine compartment but still not into the main exhaust).

Unless I'm an idiot the same rules that apply to the main exhaust more than likely will apply to the wastegate exhaust.

Hey Twistie, don't you live in KC? You can take a peek at my turbo charged RS. It might clear up any questions you have if you see it in person. I'm home usually on the weekends.

>Must not have reach professional import racing. Nearly every
>FWD I've seen has a side or rear exit open dump tube right
>along side the main exhuast (routed outside the engine
>compartment but still not into the main exhaust).
>
>Unless I'm an idiot the same rules that apply to the main
>exhaust more than likely will apply to the wastegate
>exhaust.

The example you provide would likely pass the intentions and criteria of the organizations that have enacted this rule (NMRA, NMCA, NHRA, among others). The intention of this rule is to keep open wastegate exhausts from simply venting under the hood and igniting nearby components. They've seen the fires, so they reacted. As you mentioned, the Pro cars that use a separate wastegate exhaust still vent it to the outside of the vehicle, which is the safe thing to do. It's those wastegates with no dump tube at all, or dump tubes that do not carry the discharge out and away from the engine compartment, that are potentially dangerous, especially on a street car that typically has a more tightly packed, less well ventilated engine compartment that is also likely to see higher temps and longer operation than pure race cars.

yea erik...i live in KC...i might take up that offer sometime...thanx man.