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Thread: GM Twin Turbo Tweak

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    Senior Member fatbillybob's Avatar
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    Doesn't bmw already have that? Dual phase turbo that acts like a small turbo for no lag then attributes of a big turbo to generate horsepower.

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    BMW Master bawareca's Avatar
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    Quote Originally Posted by fatbillybob View Post
    Doesn't bmw already have that? Dual phase turbo that acts like a small turbo for no lag then attributes of a big turbo to generate horsepower.
    On the diesels they have tripple turbo too, and there are rumors for 4.
    On the GM diagram i see only 1 turbo, so it could be a supercharger+turbocharger. Actually number 340 looks like electric supercharger so this may be it. Also appears that the blow-off valve is blowing into the exhaust before the turbo.

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    Senior Member Johnny_Se7en's Avatar
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    Quote Originally Posted by bawareca View Post
    ...I see only 1 turbo, so it could be a supercharger+turbocharger. Actually number 340 looks like electric supercharger so this may be it. Also appears that the blow-off valve is blowing into the exhaust before the turbo.
    The turbo set up is in block 900 Fig. 3 sheet 2 of 3 of the patent application.
    bawareca likes this.
    If nothing happens and there is no one around why did it not happen?

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    BMW Master bawareca's Avatar
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    Quote Originally Posted by Johnny_Se7en View Post
    The turbo set up is in block 900 Fig. 3 sheet 2 of 3 of the patent application.
    Got it, thanks. Good idea, except that the durability/reliability of a long shaft with 2 throttles in the exhaust stream is questionable at best. It has to work at 100 degree and at 1700 degree, to be air tight, to not stick and to withstand millions of actuations and not cost a million dollars.

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    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    Got it, thanks. Good idea, except that the durability/reliability of a long shaft with 2 throttles in the exhaust stream is questionable at best. It has to work at 100 degree and at 1700 degree, to be air tight, to not stick and to withstand millions of actuations and not cost a million dollars.
    Does it need to be air tight or is "most air going that way" good enough?

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    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Does it need to be air tight or is "most air going that way" good enough?
    "Most air" is good enough. What I meant is that the shaft must be protruding from one or both sides and it must not leak exhaust gasses from there. The backpressure could be twice as the boost on an engine like this, so we are talking about 40-60 psi. And this shaft will be a subject to a harsh temperature changes, not only when you start the engine and turn it off. When you are cruising the temp in the exhaust can drop down to 500-600F and if you step on it hard it may go over 1200F in a matter of just a few seconds.

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    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    "Most air" is good enough. What I meant is that the shaft must be protruding from one or both sides and it must not leak exhaust gasses from there. The backpressure could be twice as the boost on an engine like this, so we are talking about 40-60 psi. And this shaft will be a subject to a harsh temperature changes, not only when you start the engine and turn it off. When you are cruising the temp in the exhaust can drop down to 500-600F and if you step on it hard it may go over 1200F in a matter of just a few seconds.
    Oof. yeah that's right.

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