wastegating facts

JWT said:
I am not trying to criticize any of you or suggest that I am smarter. I am just trying to pass on some of my knowledge that I have obtained in 47 years working with Turbochargers, and with some of the leading turbocharger companies.
I am getting a little older now and it gives me a great deal of pleasure to see how popular the turbocharger has become, at my age I am as enthusiastic about turbo charging as I was in my twenties. Keep up the good work guys.

John Todd
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:poke: ;)
 
JWT said:
Think about this the exhaust gasses drive the compressor wheel, the compressor boost is controlled by opening the wastegate. The wastegate is not opened to lower the exhaust pressure; it is opened to stabilize the boost pressure.
Opening the wastegate bypasses a portion of the exhaust gasses around the turbine wheel that is driving the compressor, the remaining exhaust gas pressure must rise to maintain the compressor horse power demand, and as engine RPMs increase the diminishing exhaust volume caused by opening the wastegate must increase pressure to maintain the desired boost level, eventually rising to a higher pressure than the compressor boost.
Opening the wastegate on a duel passage turbocharger with a single passage wastegate will lower the pressure on the wastegated side; but increase the pressure on the none wastegated side; if this did not happen the boost pressure would drop with the exhaust pressure,
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I found this to be true also, confused me greatly as I expected the drive pressure to nose dive when the wg opened. This was measuring drive pressure from 1 2 3 on a stock HX35.

Jim
 
Because a turbine extracts energy as a result of a difference in pressure. For some reason I came up with the idea that when the wastegate opened it also raised the turbine back pressure. In that process lowering the differential pressure across the turbine and lowering its efficientcy.

Any fact in that theory when you are talking turbochargers?

Jim
 
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Signature600 said:
I could have swore I read it at the bottom of one of his posts...sorry Dave:kick:

Pretty easy to put the username with the name though...apparently John's not too creative:hehe:

I liked the discussion!
Chris
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:hehe: Yes it was not too hard to figure it out huh?

I do not think he was trying really hard to hide is identity but he did not want to come out wearing the bright yellow boxing gloves with BD trunks. I think it worked out perfect, it was a great thread, we laughed, we cried, we learned :hehe:
 
Diesel Freak said:
That is why I am a consultant!!!
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Hmmm...


consulting.jpg


http://www.despair.com/consulting.html
 
It's terrible and true! Management didn't really like when that month showed up on my despair calendar. They didn't like 'Nepotism' month either.
 
Here's something interesting. Did some drive pressure testing this weekend. Wastegate is set to open at 48-50psi. At 40psi I was seeing 55psi of drive pressure. At 45psi I was seeing 50psi of drive pressure. Only thing I can think of is that at 40psi the wastegate's weren't open at all and at 45psi they were just starting to crack.
 
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