Turbo/Waste gate question

[Crunch]

I know how turbochargers work, but am not real familiar with the waste gate operation. How does it engage the compressor? I read the following:



How does a turbocharger and supercharger work?

"Note that although the turbine is spun by the exhaust gases, it is only when the waste gate opens that the compressor spins. The waste gate may be controlled by an electronic boost controller. "



But what is the mechanical function that actually causes the compressor to spin?

 

[rbattelle]

The compressor is mounted on a common shaft with the turbine. The turbine expands the exhaust from the engine and extracts energy from it to provide power to the compressor (all turbines work this way).



As I understand it, the waste gate is used to prevent overspeeding your turbo. There are certain conditions where there is too much energy in the exhaust flow (such as at high RPM, when the flow rate is high). When that happens, the waste gate opens up and dumps some of the engine exhaust overboard to keep the turbine and compressor from flying apart.

 

[Crunch]

Originally posted by rbattelle

As I understand it, the waste gate is used to prevent overspeeding your turbo. There are certain conditions where there is too much energy in the exhaust flow (such as at high RPM, when the flow rate is high). When that happens, the waste gate opens up and dumps some of the engine exhaust overboard to keep the turbine and compressor from flying apart.

And that's what I thought it meant, hence the term "waste gate". But the paragraph from the Zhaust site indicated that the waste gate is what causes the compressor to engage, which led me to believe there is some kind of a clutch inside. Is the turbocharger constantly compressing and using some amount of air, or is the turbine spinning by itself at times?

 

[dieselpilot1969]

Originally posted by Crunch

And that's what I thought it meant, hence the term "waste gate". But the paragraph from the Zhaust site indicated that the waste gate is what causes the compressor to engage, which led me to believe there is some kind of a clutch inside. Is the turbocharger constantly compressing and using some amount of air, or is the turbine spinning by itself at times?

So here I guess is part two of that question:

If one were to tweek the wastegate to get a little more boost do you have to have more fuel to get extra power even with say 5 or 8 more pounds of boost or would I just be whizzing in the wind

 

[JHardwick]

Whoever wrote the info in that link was a little confused I think.



The biggest problem with a turbo was always the lag. So, a more efficient turbo that spooled quicker was the answer. Supposedly the wastegate kept the turbo from spooling out of orbit.

 

[rbattelle]

There's a solid shaft between the turbine and compressor... whoever wrote the article was confused. As long as the engine is running, the turbo is spinning. Modifying the waste gate to essentially overspeed the compressor will get you more mass flow and more pressure, but without extra fuel you won't see much (if any) performance benefit.

 

[Crunch]

Originally posted by rbattelle

There's a solid shaft between the turbine and compressor... whoever wrote the article was confused. As long as the engine is running, the turbo is spinning. Modifying the waste gate to essentially overspeed the compressor will get you more mass flow and more pressure, but without extra fuel you won't see much (if any) performance benefit.

That makes sense, and leads me to believe that if it is always spinning it is always pushing air, though it may be at levels of natural aspiration until you get your foot on it a bit. At that point more air is being forced through the system and is compressed before it passes into the manifold. Is that correct?

 

[Metalaram]

tubro

yes that is the way it works!... . the edge ez and some others come with a replacement brass elbow that has a much smaller hole in it so it takes more pressure to open the waste gate witch allows more boost to be built up before being dumped.