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Discussion Starter #1
It was in Roundel BMWCC magazine. It will be 300HP but SINGLE TURBO instead of twin.What are pros and cons?

Will it will trickle in all 35 engines including 135 in Spring?
 

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Freedom isn't free!!
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It's a twin-scroll single turbo that's in the pipeline.
 

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driving a D around RTP
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googled "twin scroll turbo"...am I correct to assume that a twin scroll single turbo is a less advanced design than a variable-vane turbo?

This sounds like it could be close to a drop-in replacement for the twin turbo. E.g., twin scroll still requires a waste gate. (according to "the sources" found by google)
 

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'Fest Advisor
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...or is twin-scroll orthogonal to variable-vane?

E.g., see the quote inside post #1 here
http://www.legacygt.com/forums/showthread.php?t=7590
A twin scroll turbine housing uses dual side by side passages into the housing. When coupled with a pulse converter manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy. The twin scroll is based off the same reasoning a tri-Y header uses: keep spent exhaust gases out of an adjacent cylinder drawing in fresh air. At high rpm on a turbo car, exhaust backpressure is usually significantly higher than atmospheric pressure, and often higher than intake manifold pressure as well. A divider between each of the two volutes allows the cylinders to expel the exhaust gases without it interfering with the fresh air for combustion. Since there are two openings, each a smaller overall volume than a single scroll design, the exhaust velocity of each pulse can be maintained. This also spins the impeller more easily because lag is a function of the scroll area. A single turbine housing opening isn't as efficient since cylinders on the exhaust stroke of the 4 stroke cycle contaminate the cylinders that are on overlap with exhaust gas. A conventional turbine housing is not as effective in using exhaust pulse energy to help spin the turbine up to speed as it does not exploit the energy contained in the pulses as well.

You actually understand that??!!
 

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Freedom isn't free!!
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A twin scroll turbine housing uses dual side by side passages into the housing. When coupled with a pulse converter manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy. The twin scroll is based off the same reasoning a tri-Y header uses: keep spent exhaust gases out of an adjacent cylinder drawing in fresh air. At high rpm on a turbo car, exhaust backpressure is usually significantly higher than atmospheric pressure, and often higher than intake manifold pressure as well. A divider between each of the two volutes allows the cylinders to expel the exhaust gases without it interfering with the fresh air for combustion. Since there are two openings, each a smaller overall volume than a single scroll design, the exhaust velocity of each pulse can be maintained. This also spins the impeller more easily because lag is a function of the scroll area. A single turbine housing opening isn't as efficient since cylinders on the exhaust stroke of the 4 stroke cycle contaminate the cylinders that are on overlap with exhaust gas. A conventional turbine housing is not as effective in using exhaust pulse energy to help spin the turbine up to speed as it does not exploit the energy contained in the pulses as well.

You actually understand that??!!
Hey, he used the word "orthogonal"! :) I like to think I have a pretty good vocabulary, but I had to look up that one.

just a little side note: I have an engineer friend who can explain how gravity bends light and slows time.
 

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Hey, he used the word "orthogonal"! :) I like to think I have a pretty good vocabulary, but I had to look up that one.

just a little side note: I have an engineer friend who can explain how gravity bends light and slows time.
The gravity effect I completely understand, but orthogonal and pulse converter manifolds, over my head. But I'm working on it and will try to have it figured out soon:thumbup:
 

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Discussion Starter #9
so, changing face lifted 335 coupe this spring to 300bhp single turbo motor will it yield better dynamics or decrease weight better fuel economy..pls advise
 

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Screw the differences in the twin turbo or single turbo theory. The difference is moot with the crappy HPFP design which they refuse to correct properly other than extending the warranty
 

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Discussion Starter #11
Screw the differences in the twin turbo or single turbo theory. The difference is moot with the crappy HPFP design which they refuse to correct properly other than extending the warranty
hmmm! so it does not save them money or help compete the competetors, nor do help drivers or customers! then why?
 

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Flying monkey herder
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the twin scroll single turbo engine is not just an updated turbo N54, its a new design, N55. hopefully they didnt take the hpfp from the n54 for this one...
 

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So, if the title of this thread is a valid one, would the epidemic of 335i coupe HPFP failures indicate a mid-life crisis?

Inquiring minds would like to know.
 

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I'd be surprised if BMW throws in the N55 in a facelift. BMW historically will only do one set of engine refreshes with a 3 series chassis. Since the E9x already has had an engine refresh (328/335 from the 325/330 engines), I expect the N54 to continue until the F30 is released.
 

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It was in Roundel BMWCC magazine. It will be 300HP but SINGLE TURBO instead of twin.What are pros and cons?

Will it will trickle in all 35 engines including 135 in Spring?
I just ordered at 2010 335i. I wasnt told of it being a single turbo?
 

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the single turbo was done purely from an emissions standpoint. this is from automobile magazine (this month's issue).

I wouldn't be surpised if this n55 engine wasn't as "great" as the n54.... esp from a power and lag perspective.
 

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Didn't Roundel say that it "might" get the single turbo for lci? By the way, when does everybody think we'll see official March 2010 ordering data and LCI pictures for the coupe? Maybe in Jan?
 

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energetik9
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Screw the differences in the twin turbo or single turbo theory. The difference is moot with the crappy HPFP design which they refuse to correct properly other than extending the warranty
Somebody had to go there......
 
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