[AltecBX]

Can we replace our existing turbos with two twin-scroll turbos? By does this, BMW is adding 100+hp to their engines. I see all the new M cars are going to have these turbos. Started with the X5 & X6. Next is going to the M5 & M7.

[Muffnbluff]

You can't really have two twin scroll turbos on a 6 cylinder car.

The idea behind twin scroll turbos is that they separate exhaust gas pulses. In our inline 6 engine each turbo is getting exhaust from three cylinders. The firing order is such that the exhaust gas pulses alternate between the turbos. So there's no real way to make a twin scroll turbo that feeds off of 3 cylinders from a 6 cylinder engine.

[GreenPlease]

You can have a single twin scroll on an I6. M isn't "adding" 100hp with twin scrolls, they are doing that with the sizing of the turbos, tuning, etc.

[ar design]

Originally Posted by Muffnbluff

You can't really have two twin scroll turbos on a 6 cylinder car.

The idea behind twin scroll turbos is that they separate exhaust gas pulses. In our inline 6 engine each turbo is getting exhaust from three cylinders. The firing order is such that the exhaust gas pulses alternate between the turbos. So there's no real way to make a twin scroll turbo that feeds off of 3 cylinders from a 6 cylinder engine.

Originally Posted by GreenPlease

You can have a single twin scroll on an I6. M isn't "adding" 100hp with twin scrolls, they are doing that with the sizing of the turbos, tuning, etc.

Nailed it.

[AltecBX]

Originally Posted by GreenPlease

You can have a single twin scroll on an I6. M isn't "adding" 100hp with twin scrolls, they are doing that with the sizing of the turbos, tuning, etc.

But if you notice the V8 engine on the 750, X6, 550GT, & next 550, they all have a V8 4.4 Twin Turbo producing 400HP. The X6M has a 4.4 Twin-Scroll Turbo producing 550HP. Same engine but different turbos. I know the M division tunes there cars (ecu, lightweight material, mufflers, headers, intercoolers, intake, suspension, wheels, etc), but the main difference here is the larger twin-scroll turbos. I believe the different in turbos account for some of the +150HP difference knowing they using the same 4.4L (4395cc) engine displacement.

My question is why is it not possible to put the twin-scroll turbos in our 6 cylinders cars but it's possible to put them in the V8 engine. And if that's the case, can I replace the turbos on a X650 or 750 to the twin-scroll turbos to increase power?

[GreenPlease]

^
I'd be willing to wager that the limiting difference between the S63B44 (M engine) and the N63 (X50i engine) is in the amount of boost allowed by the ECU along with associated fueling and timing parameters. While I don't know it for a fact, I highly doubt that the turbos on the S63B44 are actually physically larger (and therefore capable of more flow) than the turbos on the N63. I say this because of the fact that the S63B44 makes its peak torque so low in the rev range, lower in fact than the N63.

The difference in the torque curves between the S63B44 and the N63 are largely attributable to:
1. The twin-scroll turbos
2. The advanced exhaust manifold employed by the S63B44
3. Valve timings (but the N63 has valvetronic so it should actually be easier for it to have low end torque, plus it has a higher compression ratio).

If the S63B44 actually had larger snails than the N63 this wouldn't be the case: peak torque would come much later in the rev range.

[GreenPlease]

Sorry, to answer your questions directly

My question is why is it not possible to put the twin-scroll turbos in our 6 cylinders cars but it's possible to put them in the V8 engine.

You could put a twin scroll turbo on an I6, you'd just need a new exhaust manifold, new down-pipe, new oil lines, new charge pipe, and some tuning.

And if that's the case, can I replace the turbos on a X650 or 750 to the twin-scroll turbos to increase power?

This remains to be seen but I'm sure of two things:
-someone will try it
-it won't work because BMW more than likely made it so that it wouldn't be a direct bold on to the N63

Also, the N63, even with the exhaust manifold of the S63B44, would need a tune in order to achieve the power levels of the S63B44. There's a fair chance that this will not be achievable due to
-the N63 having a higher compression ratio and...
-the N63 having valvetronic

With that said, I really hope I'm proven wrong and that somebody figures out how to tune an engine with valvetronic.

[Mr. 5]

The N55 has a single twin scroll turbo.
The N55 is replacing the N54.

[AltecBX]

Originally Posted by Mr. 5

The N55 has a single twin scroll turbo.
The N55 is replacing the N54.

Yes, It will be valvetronic and have a single twin-scroll turbo, which would give us a a lower torque curve & better fuel efficiency as well.

Originally Posted by GreenPlease

Sorry, to answer your questions directly



You could put a twin scroll turbo on an I6, you'd just need a new exhaust manifold, new down-pipe, new oil lines, new charge pipe, and some tuning.



This remains to be seen but I'm sure of two things:
-someone will try it
-it won't work because BMW more than likely made it so that it wouldn't be a direct bold on to the N63

Also, the N63, even with the exhaust manifold of the S63B44, would need a tune in order to achieve the power levels of the S63B44. There's a fair chance that this will not be achievable due to
-the N63 having a higher compression ratio and...
-the N63 having valvetronic

With that said, I really hope I'm proven wrong and that somebody figures out how to tune an engine with valvetronic.

Thanks. I hope someone comes up with a way to fit these twin-scrolls on BMW non M cars. I wish tuners can start early this year on this development.

[GreenPlease]

+2

[midlife]

Originally Posted by GreenPlease

+2

Btw greenplease:
cars > women = yes
but: cars + money = women3 (third power) LOL.

[GreenPlease]

^haha

I'm surprised at how often I get comments on my sig. I guess it strikes a tone with a lot of the guys on this board

[Synergy 69]

that's a sexy pic! =)