wastegate?

[graysta]

would someone please educate me as to the function of a wategate on a turbo

[hraney]

Wastegate acts as a "safety" on a turbo'ed motor. At a preset PSI of boost, the wastegate will open and dump the boost to keep from overboosting the motor and doing things like forcing pistons through the oilpan.

[graysta]

so if you put two in series and increased the preset boost threshold then the additional turbo wouldnt need a wastegate the one would suffice correct?

[hraney]

To be honest I don't know how dual turbo systems are set up in regards to wastegates. But the wastegate dumps the boost into the exhaust so wouldn't the exhaust pressure increase in the second turbo and "pull" more air through the first turbo? Bear in mind I am just thinking out loud here.
Make a long story short, I don't know.

[sixnickel]

The turbocharger on the 6.5 supply's to much boost at high RPM WOT conditions.It will damage the engine.They use this size turbo because it works much better at lower RPM and less throttle. To keep from over boosting, the waste gate is a valve in the exhaust side of the unit that opens and bi passes the exhaust from the turbine wheel to the down pipe. This controls the speed of the compressor side of the turbo and the boost out put. The waste gate on a gas engine dumps boost on the compressor side because when you close the throttle the air flow is shut off and the boost needs to go somewhere. Remember in a diesel fuel flow controls power and a gas engine air flow controls power, there is no throttle plate in a diesel. Hope this makes sense to you.

[Violator]

I have to look again but on my new Peterbilt w/ the twin turbos the waste gate is controlled by pressure from the first one. There is only one wastegate and is located after the 2nd turbo.

[rww930]

what if the wastegate is held inthe open position while driving? what effect will it have/

[hraney]

No power, lots of black smoke.
If the wastegate is always open you basically might as well not have a turbo. All the boost will get dumped into the exhaust therefore not forcing the air charge into the motor.
Think of the waste gate as a safety. When the boost reaches a maximum, unsafe (for the motor) level, it dumps the extra (waste) boost to save the motor.