M1 engine speculation

[madfast]

Originally Posted by Levi

Who knows why M does not tune the N54 Twin-Turbo but the N55 Twin-Power-Single-Turbo to a Twin-Power-Twin-Turbo? Maybe to lift rpm up to 8.000 for a FI? The X5/X6 M do not need 8.000 rpm but the M5 does. Maybe that is why BMW says it is not excactly the same engine as the X5/X6 M. Remember the McLaren MP4-12C has a 3.8l V8 Biturbo and has redline at 8.500 rpm. Why can't BMW do that?

you must remember that the bmw turbo engines are direct injection. there is a limit to how much rpm you can have. in a port fuel injected car you can max out the injector duty cycle, which basically means the injectors are spraying non stop. thats fine for a port fuel injected engine because you are spraying into the port and not the combustion chamber. with direct injection, the injectors cant continuously spray into the combustion chamber and so there is a physical limit where the engine will simply rev faster than the fuel can be supplied. with todays technology, you simply cannot rev DI engines as high as PFI. maybe in the future, but not now.

[jmunro]

You cannot do a twin scroll, twin turbo on a 6 cylinder engine. You need an even number of cylinders to power each twin scroll turbo.

In terms of body work and appearance I'd like to see the M1 look a little less top heavy a bit lower to the ground.

[ChrisK]

Originally Posted by jmunro

You cannot do a twin scroll, twin turbo on a 6 cylinder engine. You need an even number of cylinders to power each twin scroll turbo.

^ That's the current understand of what will be in the M1. N55 Twin turbo.

[jmunro]

Originally Posted by ChrisK

^ That's the current understand of what will be in the M1. N55 Twin turbo.

Maybe an N55 with twin turbos, but not twin twin-scrolls. Essentially an N54 with Valvtronic. Each twin scroll needs an even number of cylinders to drive it.

I was hoping maybe a 3.2-3.3 liter version of the N54 with slightly larger turbos pushing it a bt closer to the displacement of the GT-R engine.

[ChrisK]

The truth is, we just don't know what the M1 will have.

[jmunro]

Originally Posted by ChrisK

The truth is, we just don't know what the M1 will have.

+1

It's fun to speculate though; it gets everyone worked up

[southlight]

Originally Posted by jmunro

Maybe an N55 with twin turbos, but not twin twin-scrolls. Essentially an N54 with Valvtronic. Each twin scroll needs an even number of cylinders to drive it.

I was doubting about this setup, either. But, some hinted at such a twin-scroll twinturbo layout. Just because it seems unusual doesn't mean it's impossible to split 6 cylinders into 4 scrolls. Hence I wouldn't rule this out yet.


Best regards,
south

[adc]

Originally Posted by madfast

you must remember that the bmw turbo engines are direct injection. there is a limit to how much rpm you can have.

I have to disagree here - the new Porsche GT3 has DI and spins well over 8000 RPM. The RPM limitation is not due to the DI, but rather to the current valvetronic technology.

BMW chose not to put DI in the M3 engine because of spiraling R&D costs and time - it would have delayed the car too much. Plus, they also rely on external suppliers/manufacturers for the fuel delivery system, and those new systems just weren't ready is what I'm guessing - see how Porsche introduced DI in their refresh cycle, not from the beginning of the 997 cars.

with direct injection, the injectors cant continuously spray into the combustion chamber and so there is a physical limit where the engine will simply rev faster than the fuel can be supplied.

The current BMW DI engines actually spray 2 times per cycle - one to deliver the main fuel load, the second time to cool the mixture. It's how they can run such high compression ratios even on FI cars.

with todays technology, you simply cannot rev DI engines as high as PFI. maybe in the future, but not now.

See above.

[jeremyc74]

Originally Posted by southlight

I was doubting about this setup, either. But, some hinted at such a twin-scroll twinturbo layout. Just because it seems unusual doesn't mean it's impossible to split 6 cylinders into 4 scrolls. Hence I wouldn't rule this out yet.


Best regards,
south

Sure it's impossible. How are you going to evenly divide 6 cylinders into four turbo inlets? The whole point of the twin scroll is to maintain the cylinder seperation advantage of twin turbo setups while reducing the overall mass of the rotating assembly. Two twin scroll turbos are simply impossible on a 6 cylinder engine.

I haven't seen anyone hint at this that actually knew what they were talking about.

[madfast]

Originally Posted by adc

I have to disagree here - the new Porsche GT3 has DI and spins well over 8000 RPM. The RPM limitation is not due to the DI, but rather to the current valvetronic technology.

check your facts. GT3 is NA and does NOT have DI. porsche Turbo DOES have DI and its redline is 7000 rpm.

and even if there are DI engines out there with a 9000+ rpm redline is there one with 10K? 12K? 15K? and for what price? what kinda injectors/fuel pressure would you need to support that much rpm?

[southlight]

Originally Posted by jeremyc74

Sure it's impossible. How are you going to evenly divide 6 cylinders into four turbo inlets? The whole point of the twin scroll is to maintain the cylinder seperation advantage of twin turbo setups while reducing the overall mass of the rotating assembly. Two twin scroll turbos are simply impossible on a 6 cylinder engine.

I haven't seen anyone hint at this that actually knew what they were talking about.

Please have a look at the following quotes.

Originally Posted by SCOTT26

The M1 will not feature a V8 that remains exclusive to the M3.
The engine is based on the updated N55 Six cylinder but reconfigured by the M Division. to accomodate Twin-Turbo and a high performance intercooler.
PS Output is at 345PS again not to tread on the toes of the M3.

Originally Posted by mapezzul

They are working on a trick manifold and yes it can be split

Best regards,
south

[atr_hugo]

FWIW, Ferrari is using DI in an NA engine that revs to 9K (Ferrari California IIRC). The Bosch Automotive handbook offers this caveat for DI engines and maximum rpm, they state that DI engines have less time to form a proper mixture than manifold injection. I suspect that that's accurate for some injection strategies and possibly boosted engines, but somehow Ferrari redlines their DI at 9K. Go figure.

[jeremyc74]

Originally Posted by southlight

Please have a look at the following quotes.






Best regards,
south

Scott doesn't say anything about twin scroll twin turbo. He simply says they're switching to twins instead of the dual scroll single turbo on the standard N55. You CAN NOT evenly divide 6 by 4. This is a very simple concept.

mapezzul either mispoke, or he doesn't understand the concept.

A twin scroll turbo has two seperate inlets, which are used to isolate the opposing cyclinders like a twin turbo setup does, but then they're both tied to one compressor wheel. Two twin scroll turbos would mean four intlets, and it won't work with 6 cylinders. Period.

[BMW269]

Maybe it is Tripple-Power-Twin-Turbo? Every turbo has on big and one smaler outlet. The two smaller are put together and make one outlet. In this way it means that from two turbos there are three oulets, and this work on I6: 2+2+2=6

[moveswiftly]

Originally Posted by Levi

Maybe it is Tripple-Power-Twin-Turbo? Every turbo has on big and one smaler outlet. The two smaller are put together and make one outlet. In this way it means that from two turbos there are three oulets, and this work on I6: 2+2+2=6

It's already been conformed that it's a TWIN-twin scroll turbo

[mapezzul]

Originally Posted by jeremyc74

Scott doesn't say anything about twin scroll twin turbo. He simply says they're switching to twins instead of the dual scroll single turbo on the standard N55. You CAN NOT evenly divide 6 by 4. This is a very simple concept.

mapezzul either mispoke, or he doesn't understand the concept.

A twin scroll turbo has two seperate inlets, which are used to isolate the opposing cyclinders like a twin turbo setup does, but then they're both tied to one compressor wheel. Two twin scroll turbos would mean four intlets, and it won't work with 6 cylinders. Period.

Oh I am perfectly aware of what a twin scroll is- I happen to have written a little something on the motor of the X5/X6 ///M versions when they were first announced.

I did not mis-speak. They were working on (last I had heard from a reliable person) on a trick manifold for this new motor, it may have a single turbo and a dual scroll or use a split path from complimentary cylinders with 2 dual scrolls. If you keep looking at what you think is normal you will never understand how these engineers look at things. They are also working on a twin turbo 3 cylinder so using your math how does that work? What they have finalized I do not know but there are a lot of possibilities when thinking outside the box, these same guys put two twin scrolls inside the "V" and re-thought head design to come up with the reverse flow concept, and change the normal firing order. The CCM was the beginning and there is a lot more coming- whether they show it in the 1 or wait for the next M3 is the real question.

But yes they can use two dual scrolls with a 6 cylinder, you need a controlled opening to the scrolls (which they have on the N55 already)... there is a lot more going on than cylinders divided by scrolls.

That being said- I am certain they will have something special in this motor and not just a plain twin turbo setup, how would that be an ///M?

We will all have to wait and see.

[jeremyc74]

Originally Posted by mapezzul

Oh I am perfectly aware of what a twin scroll is- I happen to have written a little something on the motor of the X5/X6 ///M versions when they were first announced.

I did not mis-speak. They were working on (last I had heard from a reliable person) on a trick manifold for this new motor, it may have a single turbo and a dual scroll or use a split path from complimentary cylinders with 2 dual scrolls. If you keep looking at what you think is normal you will never understand how these engineers look at things.

.

Explain how you could POSSIBLY split the complimentary cylinders on a 6 pot motor into four seperate turbo inlets. PLEASE!

You have 6 exhaust outlets, and 4 turbo inlets to feed. Give us the layout. Which cylinder goes to which turbo? There's no need for twin scrolls in this application becuase the opposing cylinders are already seperated. It would serve no purpose.

Originally Posted by mapezzul

They are also working on a twin turbo 3 cylinder so using your math how does that work?
.

If they are actually working on this (which I doubt because it doesn't make much sense unless it's a sequential setup instead of a "twin") all three cylinders would have to go into a common manifold, feeding both turbos.

Originally Posted by mapezzul

What they have finalized I do not know but there are a lot of possibilities when thinking outside the box, these same guys put two twin scrolls inside the "V" and re-thought head design to come up with the reverse flow concept, and change the normal firing order. The CCM was the beginning and there is a lot more coming- whether they show it in the 1 or wait for the next M3 is the real question.

The reverse flow heads like the ones on the X6 aren't new. They've been around for decades.

Originally Posted by mapezzul

But yes they can use two dual scrolls with a 6 cylinder, you need a controlled opening to the scrolls (which they have on the N55 already)... there is a lot more going on than cylinders divided by scrolls.
We will all have to wait and see.

Controlled opening? You're saying they're going to alternate the exhaust path with every revolution of the crankshaft? At 7k RPM? You can't be serious.

[jeremyc74]

Originally Posted by chesterfan1230

It's already been conformed that it's a TWIN-twin scroll turbo

No, it hasn't. No one from BMW has EVER said anything about twin scroll turbos on this car.

[jmunro]

Originally Posted by jeremyc74

Explain how you could POSSIBLY split the complimentary cylinders on a 6 pot motor into four seperate turbo inlets. PLEASE!

You have 6 exhaust outlets, and 4 turbo inlets to feed. Give us the layout. Which cylinder goes to which turbo? There's no need for twin scrolls in this application becuase the opposing cylinders are already seperated. It would serve no purpose.



If they are actually working on this (which I doubt because it doesn't make much sense unless it's a sequential setup instead of a "twin") all three cylinders would have to go into a common manifold, feeding both turbos.



The reverse flow heads like the ones on the X6 aren't new. They've been around for decades.



Controlled opening? You're saying they're going to alternate the exhaust path with every revolution of the crankshaft? At 7k RPM? You can't be serious.

Im glad to see there are other people on this board that actually think. Maybe a twin tri-scroll turbo. Seems like too much manifold work to fit in the 1 engine bay though.

[southlight]

Originally Posted by jeremyc74

You have 6 exhaust outlets, and 4 turbo inlets to feed. Give us the layout. Which cylinder goes to which turbo? There's no need for twin scrolls in this application becuase the opposing cylinders are already seperated. It would serve no purpose.

No, the cylinders aren't fully separated. No matter if one twin-scroll or one twin-turbo is used, there's one cylinder's exhaust outlet in each channel causing turbulences. Hence the need for at least three different channels. For this reason, a twin-scroll twinturbo setup is not only possible, but also does provide advantages over the current setup. Assuming the conservative way of an uneven split would still be an improvement over one twin-scroll.


Best regards,
south

[adc]

Originally Posted by madfast

check your facts. GT3 is NA and does NOT have DI. porsche Turbo DOES have DI and its redline is 7000 rpm.

My bad.

and even if there are DI engines out there with a 9000+ rpm redline is there one with 10K? 12K? 15K? and for what price?

For me, 8000 is enough.

Originally Posted by atr_hugo

FWIW, Ferrari is using DI in an NA engine that revs to 9K (Ferrari California IIRC). The Bosch Automotive handbook offers this caveat for DI engines and maximum rpm, they state that DI engines have less time to form a proper mixture than manifold injection. I suspect that that's accurate for some injection strategies and possibly boosted engines, but somehow Ferrari redlines their DI at 9K. Go figure.

[jeremyc74]

Originally Posted by southlight

No, the opposing cylinders aren't fully separated. No matter if one twin-scroll or one twin-turbo is used, there's one cylinder's exhaust outlet in each channel causing turbulences. Hence the need for at least three different channels. For this reason, a twin-scroll twinturbo setup is not only possible, but also does provide advantages over the current setup. Assuming the conservative way of an uneven split would still be an improvement over one twin-scroll.


Best regards,
south

I honestly can't believe I'm even having this discussion.

EXPLAIN how you evenly divide 6 by 4, or stop posting this nonsense!

You damn sure can't feed the turbos with different numbers of cylinders. Three turbos would be possible, because that's evenly divisable by 6, but two twin scrolls is NOT possible because that means FOUR inlets. PERIOD.

In a twin turbo setup the opposing cylinders are COMPLETLEY isiolated from each other. They're on totally seperate turbos! There's only one exhaust pulse at a time going on when a bank of 3 cylinders is feeding a turbo because the others are either in their intake or compression stroke.