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      09-07-2010, 12:41 PM   #89
madfast
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Originally Posted by sparoz View Post
Imagine you are spinning the spool with your left hand and right hand. You do it once with your left and twice with your right - it works (I know it is over simplistic).

The way I see it is that having two pulse on one scroll is definitely better that three on one scroll. If you look at firing sequence 1 2 3 4 5 6 (not cylinders), where Turbo A connects to 1 3 5 and Turbo B connects to 2 4 6; Scroll A1 connects to 1, 5, and A2 connects to 3, Scroll B1 connects to 2, 6 and B2 connects to 4. The volume and pulses feed to the charger is the same - 3 by volume of air, and they would be evenly spaced out regardless of the uneven scrolls as the two scrolls feeds to one charger. The continuous feeding of the charger should create the back pressure require on the two scrolls, while the separation of the two cylinders on one scroll and the isolation of the one cylinder on the other should reduce interference. Timing, as far as I know is done by the size and length of the runners in the manifold - CCM is the latest BMW technology. As the key to this set up is in the manifold, I believe BMW, who is renowned for this would be able to come up with a solution.

I am no engineer but that's why I can't see why it is a problem, and of course due to my limited knowledge and understanding. However, I think I am guilty of getting this OT. Let's go back to the N54.
yes, but if you spin once with your left and twice with your right, you can run into interference on the right side. for instance lets say you spin the wheel at a constant speed. with the left hand, you spin it once and the whole spin is completed. with the right hand however, as soon as you finish the first spin, you must spin it again. that's where interference comes into play. the faster you spin (more rpm) the first spin with your right hand may not have finished when you begin the second spin. this would then defeat the whole purpose of twin scroll to begin with, because there is interference from 2 pulses into 1 scroll too close together.

if you look at your example, the spacing between 1 and 5 is fine, but the spacing between 5 and 1 isnt. they're too close together.

is 2 twin scroll possible? yes of course. is it worth it? i dont think so...
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      09-07-2010, 01:45 PM   #90
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It seems possible to have a twin scroll setup on a 3 cylinders engine (cf url)

http://www.bimmerfile.com/2010/05/12...linder-driven/

But i would rather than BMW will not spend money and add weight on the car.

They will add there CCM + the Turbo from the N55 for a weight gain of 20-25kg.

Maybe carry over the injectors and HPP from the N55.

The rest will be carry over from the N54 (maybe a change in the cam timing aswell)

And then that sound like a new S54 engine for me

PS : Or at least i hope so ...

edit : another example use by audi for the twin scroll on uneven number of cylinder (aka TT RS) => Twin-scroll turbos are ideal for inline fours but the odd number of cylinders precludes it here. Instead, the engineers designed the manifold so that the feed from cylinder number three is kept apart from the others until it enters the turbine housing volute.
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      09-07-2010, 06:01 PM   #91
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Ok so why wouldn't the exhaust manifold have a trick flap that is controlled by a solenoid that is connected to the cams and ecu to alternate the 3rd pulse back and forth between firing cycles? I am mechanically and engineerically challenged but wouldn't that be an option? Wouldn't fill the trick manifold as well? or maybe ^ all that but for the intake side? Just wondering?
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      09-07-2010, 07:10 PM   #92
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A fascinating discussion on multi scroll turbine housings.
We're so fortunate that BMW has given M Division carte-blanche to go ahead and come up with the most technologically advanced inline turbo six yet, years ahead of the current status-quo, time and researchdollars no object, and we eagerly await the fruits of those developments!!!!!
Such a tour-de-force piece of machinery will surely completely shame the 330hp the N54 is currently tuned to in it's Z4 version. Surely we're talking the first 550hp production 3 liter!


Oooops, I think I just woke up......
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      09-07-2010, 07:55 PM   #93
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Originally Posted by Future M1 owner View Post
A fascinating discussion on multi scroll turbine housings.
We're so fortunate that BMW has given M Division carte-blanche to go ahead and come up with the most technologically advanced inline turbo six yet, years ahead of the current status-quo, time and researchdollars no object, and we eagerly await the fruits of those developments!!!!!
Such a tour-de-force piece of machinery will surely completely shame the 330hp the N54 is currently tuned to in it's Z4 version. Surely we're talking the first 550hp production 3 liter!


Oooops, I think I just woke up......
Haha.. that hurts! While reading I was praying you were some sort of bmw insider laying it out for us!
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      09-07-2010, 09:37 PM   #94
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Quote:
Originally Posted by madfast View Post
yes, but if you spin once with your left and twice with your right, you can run into interference on the right side. for instance lets say you spin the wheel at a constant speed. with the left hand, you spin it once and the whole spin is completed. with the right hand however, as soon as you finish the first spin, you must spin it again. that's where interference comes into play. the faster you spin (more rpm) the first spin with your right hand may not have finished when you begin the second spin. this would then defeat the whole purpose of twin scroll to begin with, because there is interference from 2 pulses into 1 scroll too close together.

if you look at your example, the spacing between 1 and 5 is fine, but the spacing between 5 and 1 isnt. they're too close together.

is 2 twin scroll possible? yes of course. is it worth it? i dont think so...
Not sure if it's worth it, but at the moment - you have to spin it three times on each scroll. 5-1 will have the same sort of interference as the current 5-1 situation.

Quote:
Originally Posted by emos325 View Post
Ok so why wouldn't the exhaust manifold have a trick flap that is controlled by a solenoid that is connected to the cams and ecu to alternate the 3rd pulse back and forth between firing cycles? I am mechanically and engineerically challenged but wouldn't that be an option? Wouldn't fill the trick manifold as well? or maybe ^ all that but for the intake side? Just wondering?
I guess that's possible but that means that each inlet has to had a valve like that... isn't that a bit complex?
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      09-08-2010, 12:37 AM   #95
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Quote:
Originally Posted by madfast View Post
yes, but if you spin once with your left and twice with your right, you can run into interference on the right side. for instance lets say you spin the wheel at a constant speed. with the left hand, you spin it once and the whole spin is completed. with the right hand however, as soon as you finish the first spin, you must spin it again. that's where interference comes into play. the faster you spin (more rpm) the first spin with your right hand may not have finished when you begin the second spin. this would then defeat the whole purpose of twin scroll to begin with, because there is interference from 2 pulses into 1 scroll too close together.

if you look at your example, the spacing between 1 and 5 is fine, but the spacing between 5 and 1 isnt. they're too close together.

is 2 twin scroll possible? yes of course. is it worth it? i dont think so...
5 and 1 never use the same turbo.
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      09-08-2010, 03:07 PM   #96
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I was talking with the guys at my local BMW dealership. Their comments were that the 1M Coupe, will come in at 340 HP, and that the gearing (presumably the gearbox and rear end) will be tuned to maximize performance characteristics. With what is already known, about the engine, and car only having a manual transmission, this would not be a surprise to me.

I think people that are looking for a 360+ HP car may well be disappointed. I have a feeling this will still be an exciting car to drive.
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