BMW announces next generation engine families will share up to 60% of their parts between motors, same blocks

[fundahl]

I dont see an issue, 3 cylinders go to one turbine housing inlet. The inlet is split, so what? Its not like 3 cylinders have to merge to 2 then to one. Twin scroll doesnt mean anything except that the housing is partitioned, it still has one inlet flange or in the case of the N55 and N54 with welded manifolds; one inlet.

The n54 twin turbo setup would not work well with twin-scrolls because it's hard to balance exhaust flow when you split a runner in half and merge it with two full sized runners.

have you seen a twin scroll flange? it doesnt have one inlet....

[Sticky]

have you seen a twin scroll flange? it doesnt have one inlet....

He said it doesn't have on inlet. He is saying you can still merge more than just 2 cylinders into it.

[fundahl]

lol all i'm trying to say is it's not practical to merge half an exhaust runner to each side of the twin-scroll flange. therefor a twin-scroll usually wouldnt be used with a 3 cylinder, or two twin scrolls with a 6 cylinder.

[Sticky]

lol all i'm trying to say is it's not practical to merge half an exhaust runner to each side of the twin-scroll flange. therefor a twin-scroll usually wouldnt be used with a 3 cylinder, or two twin scrolls with a 6 cylinder.

It isn't practical but it could be done.

[DBFIU]

It would be a hell of a lot easier to swap turbos from common pedigree engines than waiting 5 years for a basic single turbo kit.

[fundahl]

I'm just surprised there is so little custom fabrication for N54s/N55s. We shouldn't need to swap anything, we can build it. I think it's a combo of expense of these new cars and difficulty in tuning/tricking BMW's DME.

A GTX3582 is all the N54 needs compressor-wise to hit 600+whp.

[lughed]

This is nothing new. The s14, m30, s38 in all variations are practically the same block. Same goes for all the e36 chassy engines, e46, the v8's and so on. Nothing new.

[Sticky]

This is nothing new. The s14, m30, s38 in all variations are practically the same block. Same goes for all the e36 chassy engines, e46, the v8's and so on. Nothing new.

This is new. The S14 is a different block.

The S38 is pretty different as well.

What they are doing here is giving all the cylinders the same bore so they can use the same pistons and rods. The only change will be the amount of cylinders so this will all be modular with the same bore x stroke. The motors you mentioned differ in this regard.

[radasaurus]

It isn't practical but it could be done.

I think you/DBFIU misunderstand the purpose of a twin scroll turbocharger...It is not just impractical to feed two scrolls with three cylinders, it makes no sense at all. The point of a twin scroll design is to separate the exhaust pulses that in an undivided manifold collide with each other and result in lost energy. There is none of this interference among a bank of 3 cylinders. Even if there were pulses interfering with each other, splitting 3 cylinder's exhaust into two scrolls on a turbocharger is not going to yield any of the benefits of the twin scroll design. Rather, splitting a single cylinder's exhaust into two (or pairing two of the cylinders into one scroll and the third into the other) would likely only introduce turbulence in the exhaust manifold and cause a restriction when compared to an open/undivided/single scroll configuration.

So whether or not it "could" be done is irrelevant (I would maintain that it can't be done in a mass produced engine). If you don't understand why, think about who designs engines and who pays for it.

[Sticky]

I think you/DBFIU misunderstand the purpose of a twin scroll turbocharger...It is not just impractical to feed two scrolls with three cylinders, it makes no sense at all. The point of a twin scroll design is to separate the exhaust pulses that in an undivided manifold collide with each other and result in lost energy. There is none of this interference among a bank of 3 cylinders. Even if there were pulses interfering with each other, splitting 3 cylinder's exhaust into two scrolls on a turbocharger is not going to yield any of the benefits of the twin scroll design. Rather, splitting a single cylinder's exhaust into two (or pairing two of the cylinders into one scroll and the third into the other) would likely only introduce turbulence in the exhaust manifold and cause a restriction when compared to an open/undivided/single scroll configuration.

So whether or not it "could" be done is irrelevant (I would maintain that it can't be done in a mass produced engine). If you don't understand why, think about who designs engines and who pays for it.

I don't think I have misunderstood the purpose of a twin scroll supercharger at all as I have explained the topic quite well in an article I wrote on the N63/S63: http://www.bimmerboost.com/showthrea...and-S63-motors

The question wasn't if it was practical it was more of one asking if it could be done. Sure, it wouldn't have the benefits of the V8 firing order but it could be done.

[DBFIU]

I think you/DBFIU misunderstand the purpose of a twin scroll turbocharger...It is not just impractical to feed two scrolls with three cylinders, it makes no sense at all. The point of a twin scroll design is to separate the exhaust pulses that in an undivided manifold collide with each other and result in lost energy. There is none of this interference among a bank of 3 cylinders. Even if there were pulses interfering with each other, splitting 3 cylinder's exhaust into two scrolls on a turbocharger is not going to yield any of the benefits of the twin scroll design. Rather, splitting a single cylinder's exhaust into two (or pairing two of the cylinders into one scroll and the third into the other) would likely only introduce turbulence in the exhaust manifold and cause a restriction when compared to an open/undivided/single scroll configuration.

So whether or not it "could" be done is irrelevant (I would maintain that it can't be done in a mass produced engine). If you don't understand why, think about who designs engines and who pays for it.

Hello, I design gas turbines for a living. I know how and why the twin scroll turbo functions. Just because it is not necessary to have the twin scrolls on the bank of 3 cylinders (half of the I6) doesnt really have anything to do with whether the swap can be done. You're right, it isnt necessary to have a twin scroll turbo on one bank of three cylinders, but if the swap is easy and if each I4 turbo variant produces more mass flow than one turbo off the I6; go ahead and swap two I4 turbos onto the I6. The twin scroll housing is just there for the ride, if it hinders performance (probably not) it will more than be made up for having two larger turbos on the I6 after this swap.

Basically what Im saying is simple, who cares if there is a twin scroll housing on ONE turbo variant; its not difficult to plumb and would be a nice swap if you took two of those puppies and merged it unto the I6 variant.

[lughed]

This is new. The S14 is a different block.

The S38 is pretty different as well.

What they are doing here is giving all the cylinders the same bore so they can use the same pistons and rods. The only change will be the amount of cylinders so this will all be modular with the same bore x stroke. The motors you mentioned differ in this regard.

Ok, yes you are right. I guess i misunderstood what was being said. Thanks for the clarification.

[radasaurus]

Hello, I design gas turbines for a living. I know how and why the twin scroll turbo functions. Just because it is not necessary to have the twin scrolls on the bank of 3 cylinders (half of the I6) doesnt really have anything to do with whether the swap can be done. You're right, it isnt necessary to have a twin scroll turbo on one bank of three cylinders, but if the swap is easy and if each I4 turbo variant produces more mass flow than one turbo off the I6; go ahead and swap two I4 turbos onto the I6. The twin scroll housing is just there for the ride, if it hinders performance (probably not) it will more than be made up for having two larger turbos on the I6 after this swap.

Basically what Im saying is simple, who cares if there is a twin scroll housing on ONE turbo variant; its not difficult to plumb and would be a nice swap if you took two of those puppies and merged it unto the I6 variant.

I agree with what most of what you've written. I apologize for misjudging your knowledge on the subject. After reviewing the rest of your posts in this thread
We are talking about different things really; you seem to be talking about fitting twin scroll turbos onto 'regular', single scroll/undivided exhaust manifolds. I agree with you that this would be an easy swap, but as you said the twin scroll housing is "just there for the ride". This is not a twin scroll configuration at all really.

Sure, you can throw a turbo with a divided turbine housing on an undivided manifold, but you will not experience any of the benefits a true twin scroll configuration has to offer. Using undivided turbine housings would be 'better' and develop more power, all else being equal.

My comments regarding whether or not it could be done were in reference to a manufacturer mass-producing an engine with an odd number of cylinders per twin scroll turbo.
Could you develop an inline 6 with two functional twin-scroll turbochargers? No.
Could you throw a divided-housing turbo on an undivided manifold and have it work? Yes. (I know this has been done without issue using the GT4088R, which comes only in a divided housing, on m50-based motors with undivided manifolds).
Is it ideal? No.

[fundahl]

thank you.

in the end all of my vehicles end up getting custom turbo systems anyway.

sorry if i offended anyone, i just wanted to explain what realisticly is done with twin scroll turbines and exhaust manifolds.