New BMW Engine, 3.0 I6 TwinPower Turbo (N55)

[Mr Robert]

As far as I know (but I could be wrong - since I'm not a powertrain engineer) both N54 & N55 don't feature classic totally vertical (90o) block placement. Due to all the turbo stuff at the side of the engine - and therefore the block has to be a be tilted.

So, what's the point of an I6 then if the cylinders aren't vertically aligned? Isn't that one of the main point? Vertical alignment for better balance & engine run?

I think many I-configuration engines are more or less tilted for various reasons. The point of the I6 configuration is that it inself produces very little internal vibration as it is a very balanced layout, just like the V12 (F6 and F12 engines are also blessed in this way). That does not change if you tilt it a few degrees. The V6, on the other hand is a configuration that, in this respect, is flawed and will always produce more internal vibration - or unbalance, if you like.

 

[Monster]

The real interesting question here is whether the same methodology applied to the new S63 engine (X5/X6 M) will make it onto the upcoming M 6-cylinder engine.

The methodology that I speak of is the patented exhaust system. I believe that it is a function of the new V8's turbo's being housed in the V thus allowing for the "Reverse-Flow" characteristics.

What I am really getting at here (and this is my own take based on reading the various technical write-ups on these magnificent powerplants), is that the key design requirement for the Reverse-Flow and M patented exhaust / turbo flow system is the fact that the engine is a V configuration and thus can have the turbo's housed on the inside of the V versus the traditional outside.

I actually find this quite concerning as it could mean the end of the venerable BMW inline 6, as this new technology seems only to be applicable to a V engine thus adding a bit more fuel to the fire that BMW may be switching to a V6 for the next range of engines (although the new N55 rebukes that assumption).

Nonetheless, it is an interesting debate and one that I am personally quite intrigued by. There is no doubt that BMW offer us amazing technical insight into each new engine that they release and it is great - everything they do (engine wise) just seems to be so far ahead of the competition (and I am not wanting to start a war over this, it is my own personal take on the subject).

Martin - From a technical understanding and analysis, you seem to have the best insight on this forum. What is your take on my point of view? Is the new M patented exhaust system (that allows for consistent versus irregular gas pules into the turbo chargers) only applicable in a V engine with reverse-flow?

Thank you to all for a very informative thread so far

Regards,
Dylan

I don't know if the BMW's exhaust arrangement is actually patented, as far as I know, housing the turbo between the cylinder banks isn't new, MB has that layout for their V6 diesel, although it was only a single turbo.

The twin scroll turbo setup has been used by Subaru and Mitsubishi for a few years now, so it isn't a special application for a V engine with reverse gas flow, not sure if that is what you are after, but that is my answer.

 

[nalyd]

This is take from the X5 / X6 M press release - the exhaust manifold is a patented design. The purpose is to create "regular" exhaust gas pulses for the twin-scroll turbo's which apparently completely eradicates turbo-lag plus gives greater throttle response.

It is this very clever exhaust manifold that has me guessing that the new M3 will have a V6 - Apparently the concept is unique to a reverse flow engine (which an inline 6 cannot be).

Here is an excerpt from the BMW press release:

The first modern turbocharged M engine: twin scroll twin turbo technology with a patented exhaust manifold.
Using BMW’s innovative, 4.4L reverse-flow V8 engine with High Precision Direct Injection and twin turbochargers as a basis, the new M engine introduces twin-scroll twin turbochargers and patented exhaust manifold technologies to achieve outstanding thrust and pulling force, while preserving the most compact dimensions possible. Two low-mass twin-scroll turbochargers are positioned together with the catalytic converters in the “V” section between the two banks of cylinders. By reversing the flow of gases through the engine from traditional arrangements, the intake and exhaust ducts are shortened and widened. The result is that pressure losses on the exhaust side are minimized.

The goals: virtually eliminate turbocharger lag while maximizing combustion efficiency and power output. Tremendous power and performance are delivered by the engine in the BMW X5 M and BMW X6 M through a new design and construction principle. The new M V8 engine with twin-scroll twin turbo technology uses a single exhaust manifold with tuned-length runners, incorporating both cylinder banks and connecting cylinders in carefully-selected pairs. This configuration, patented by BMW M and known as Cylinder-bank Comprehensive Manifold (CCM), offers lightning-quick response, a linear build-up of engine power, and a broad, consistent torque curve by feeding each of the twin turbochargers with a “charge pulse” at approximately every 90 degrees of crankshaft rotation, rather than the more traditional “irregular schedule” of charging.

The managed flow of exhaust gas provided by the CCM ensures high-velocity flow of combustion gases. The appropriate separation of exhaust gas flow from different cylinders is maintained until the gas reaches the turbine wheel, spooling the two twin-scroll turbochargers without back-pressure. With maximum boost pressure of 1.5 bar (21 psi), the use of twin-scroll twin turbo technology and the CCM exhaust manifold allows complete exploitation of the benefits of turbocharging.

Looking forward to Martin's take on this.

 

[Mr Robert]

It is this very clever exhaust manifold that has me guessing that the new M3 will have a V6 - Apparently the concept is unique to a reverse flow engine (which an inline 6 cannot be).

That is the first viable reason I have heard this far to use the inferior V6 layout instead of the gloriuos I6.

 

[Monster]

This is take from the X5 / X6 M press release - the exhaust manifold is a patented design. The purpose is to create "regular" exhaust gas pulses for the twin-scroll turbo's which apparently completely eradicates turbo-lag plus gives greater throttle response.

It is this very clever exhaust manifold that has me guessing that the new M3 will have a V6 - Apparently the concept is unique to a reverse flow engine (which an inline 6 cannot be).

Here is an excerpt from the BMW press release:

The first modern turbocharged M engine: twin scroll twin turbo technology with a patented exhaust manifold.
Using BMW’s innovative, 4.4L reverse-flow V8 engine with High Precision Direct Injection and twin turbochargers as a basis, the new M engine introduces twin-scroll twin turbochargers and patented exhaust manifold technologies to achieve outstanding thrust and pulling force, while preserving the most compact dimensions possible. Two low-mass twin-scroll turbochargers are positioned together with the catalytic converters in the “V” section between the two banks of cylinders. By reversing the flow of gases through the engine from traditional arrangements, the intake and exhaust ducts are shortened and widened. The result is that pressure losses on the exhaust side are minimized.

The goals: virtually eliminate turbocharger lag while maximizing combustion efficiency and power output. Tremendous power and performance are delivered by the engine in the BMW X5 M and BMW X6 M through a new design and construction principle. The new M V8 engine with twin-scroll twin turbo technology uses a single exhaust manifold with tuned-length runners, incorporating both cylinder banks and connecting cylinders in carefully-selected pairs. This configuration, patented by BMW M and known as Cylinder-bank Comprehensive Manifold (CCM), offers lightning-quick response, a linear build-up of engine power, and a broad, consistent torque curve by feeding each of the twin turbochargers with a “charge pulse” at approximately every 90 degrees of crankshaft rotation, rather than the more traditional “irregular schedule” of charging.

The managed flow of exhaust gas provided by the CCM ensures high-velocity flow of combustion gases. The appropriate separation of exhaust gas flow from different cylinders is maintained until the gas reaches the turbine wheel, spooling the two twin-scroll turbochargers without back-pressure. With maximum boost pressure of 1.5 bar (21 psi), the use of twin-scroll twin turbo technology and the CCM exhaust manifold allows complete exploitation of the benefits of turbocharging.

Looking forward to Martin's take on this.

Well I am no Martin but I do enjoy some good technical discussion. From my understanding, the patented exhaust system is a result of some good exhaust gas tuning. IMO it is a clever design, but nothing spectacular And I don't buy this "completely eradicates turbo-lag'' marketing talk, there will still be lag, but significantly minimized. If the engineers from BMW can completely eliminate turbo lag, then companies like Bosch and Siemens would have wasted millions on developing electric assisted turbos or air bearings for the turbo shaft.

 

[Mr Robert]

I agree, there will be lag, the question is, rather, how much.

 

[Sunny]

That is the first viable reason I have heard this far to use the inferior V6 layout instead of the gloriuos I6.

More compact, lower cog, better weight distribution, more rigid would be other reasons.

 

[Monster]

More compact, lower cog, better weight distribution, more rigid would be other reasons.

The V6 might be heavier due to more complex geartrain as well as the need for balance shafts.

 

[Monster]

I agree, there will be lag, the question is, rather, how much.

We will never know unless BMW release their technical research paper.

 

[Mr Robert]

More compact, lower cog, better weight distribution, more rigid would be other reasons.

But none of the above have been substantial enough to invoke change before, right? It will probably be more compact, at least shorter. Lower COG, could be, in the standard case of NA engines it would be true but who knows what happens when the turbo system is installed.

 

[EnI]

The only major setbacks of V6 are a bit higher weight, and the vibrations from the engine - not as cultivated engine run as the I6.

But both issues can be eliminated - by using lightweights materials & some special fixing solutions. Yet in this case one major advantage - lower development & producing costs - is no longer there. So ...

Regarding the turbo lag - in the N55 case the max. torque & linear power distribution starts already at 1.200rpm. I'm sure BMW can go even lower - and with some smooth automatic (eg. the new 8-speed ZF auto) gearbox I'm sure the lag will be almost unnoticeable. Not to mention super-fast FlexRay protocol running between ECU & the engine ...

Yet at least the Europeans don't care much - since the vast majority drive diesels - with quite noticeable turbolags.

 

[nalyd]

Hi Monster - thanks for the response.

As I have already been quite clear on, I do not have a technical background, so I am certainly the wrong person to enter a debate on the whether BM<W has managed in their quest for complete turbo lag eradication.

What I will say is that the upcoming press drive's of both the X5 and X6 M have me quite intrigued to see the journo take on the new engine.

BMW have clearly stated that the reverse-flow engine with the close proximity of the cats is already a step towards reducing the effects of lag on the Twin-Turbo V8 - the CCM is obviously a further development on the same principle.

Whilst I also do not buy that these concepts will completely eradicate the effects of both turbo-lag and heat soak, I have to say that they are further towards an actual technical solution that any other turbo engine currently in production - this cannot be denied.

The real reason for my comment is the I6 vs V6 scenario for the upcoming M3 engine. If BMW are putting so much thought into this design, surely in the interests of scalability, BMW would want to develop the concept up and down their performance engine range?

Food for thought.

I must also add that this new N55 engine has taken me completely by surprise. When I first saw the press release, I was disappointed that the updated motor with Valvetronic was releasing the same power and torque figures - Upon review and seeing that it is in fact 1 twin-scroll turbo instead of the two on the N54, I must admit that I was pleasantly surprised.

What happens when we get Twin Twin-Scroll turbo's on the I6 - is that the new M performance engine?

Eni - your feedback has me confused. You seem to warm to the idea of a BMW V6 - this is a frightening thought!

 

[EnI]

Eni - your feedback has me confused. You seem to warm to the idea of a BMW V6 - this is a frightening thought!

I'm just saying V6 in a BMW doesn't sound as blasphemous as someone may think. I'm indifferent - as long the engine is almost as smooth and as responsive as older I6 engines. I'm do not prefer a certain tech - as long the result is the same, or almost the same.

 

[Mr Robert]

I'm just saying V6 in a BMW doesn't sound as blasphemous as someone may think. I'm indifferent - as long the engine is almost as smooth and as responsive as older I6 engines. I'm do not prefer a certain tech - as long the result is the same, or almost the same.

In part I'm with you on this. But why settle with almost as smooth? Is it indeed this new turbo technology that is not suited for an I6 layout that has pushed BMW towards the inferior V6 layout?

Your black box point is, however, quite good. Surely everyone here remember back in 1998 when we got news about the M5 getting a V8? There was alot of upset. Everyone was thinking that BMW would put the type of V8 we were familiar with in the M5... and when that was not the case, all was fine again. There were just a few lovers of the old American V8 that could not give it a rest.

Problem is, this time it is not the need for more power that forces a change of engine layout.

 

[nalyd]

Sorry - I did not mean to comment on your actual like or dislike - I am more interested in your response based on your deeper than most inside track on BMW development.

I agree that a BMW V6 is plausible - there will obviously be an outcry from brand aficionados, but at the end of the day BMW has to look at scalability in its different powertrain engineering projects.

 

[Mr Robert]

I agree that a BMW V6 is plausible - there will obviously be an outcry from brand aficionados, but at the end of the day BMW has to look at scalability in its different powertrain engineering projects.

No problem, there is always Porsche for those of us who like what BMW once stood for.

 

[Zafiro]

I'm not going to stop buying a BMW if they start with V6 but of course its very very sad if BMW decide to abandon I6 engines.

 

[klier]

^ Relax, it's just Eni trying to push those thoughts into our minds. There is no V6 BMW coming. BMW 'creative marketing' threw that in for more debate. Remember, debate = publicity...it's one of Eni's finest lines.....

 

[Betty Swollocks]

^ Relax, it's just Eni trying to push those thoughts into our minds. There is no V6 BMW coming. BMW 'creative marketing' threw that in for more debate. Remember, debate = publicity...it's one of Eni's finest lines.....

I fear you're going to be mistaken.

 

[klier]

I truly hope it's like that