[CSL335i]

These twins will replace the factory turbos, with custom made manifolds as well, so both of each turbo will be connected to 3-3 cylinders. There is a good reason, as a good idea stands behind it, why we use different size of turbine housing and different size of wastgate on each turbo. The larger turbine house will have smaller wastgate compared to the smaller turbine house, which will have larger wastgate. We named it "twin-scroll" effect. At this moment i can't tell you, how they will work againts factory turbos or RB turbos, only time will tell. These turbos will spool up a little bit later than factory ones, but we try to built many-many small tricks and ideas to decrease the gap as small as possible.

Upgrade n54 with twin-scroll (or at least divided) turbine housing turbo is also a good idea, and maybe simplier than my project. We have tried to purchase EFR 7670, but BW could not sell it (the twin-scroll turbine housee) EFR 7670, so we choose another way.

Regarding the different turbo upgrades (RB, ASR, Shiv single,...): There are always different PATHS to walk through. All of them have advantages and disadvantages compared to each other.

[jippii ensio]

Originally Posted by CSL335i

These twins will replace the factory turbos, with custom made manifolds as well, so both of each turbo will be connected to 3-3 cylinders. There is a good reason, as a good idea stands behind it, why we use different size of turbine housing and different size of wastgate on each turbo. The larger turbine house will have smaller wastgate compared to the smaller turbine house, which will have larger wastgate. We named it "twin-scroll" effect. At this moment i can't tell you, how they will work againts factory turbos or RB turbos, only time will tell. These turbos will spool up a little bit later than factory ones, but we try to built many-many small tricks and ideas to decrease the gap as small as possible.

Upgrade n54 with twin-scroll (or at least divided) turbine housing turbo is also a good idea, and maybe simplier than my project. We have tried to purchase EFR 7670, but BW could not sell it (the twin-scroll turbine housee) EFR 7670, so we choose another way.

Regarding the different turbo upgrades (RB, ASR, Shiv single,...): There are always different PATHS to walk through. All of them have advantages and disadvantages compared to each other.

Having a large WG in small housing and vice versa makes sense. however, already the stock configuration having twin turbos, is equal to having twin scrolls, one scroll in each turbo. Twin scroll is very important, but is there any additional need to enhance it from what it is already?

[Sered]

Originally Posted by The Morkinator

It's cheaper to make two cast Iron manifolds, by a lot.

I think you misunderstand how much it costs to make a CAST IRON manifold. It requires a mold, which is more expensive to make than even a few tubular manifolds.

If you're talking about two log manifolds; then yes, those are generally cheaper than a tubular; even though they don't flow as well and will limit the torque output. You also have to count that you're buying another turbo, and a single that flows equivalently doesn't cost anywhere near 2x as much. Twin IC piping, twin intakes, etc, etc. It's cheaper to do a single

[CSL335i]

Originally Posted by jippii ensio

Having a large WG in small housing and vice versa makes sense. however, already the stock configuration having twin turbos, is equal to having twin scrolls, one scroll in each turbo. Twin scroll is very important, but is there any additional need to enhance it from what it is already?

Dear jippii ensio! You point it out well. To be more specific regarding the sizes:

ft_th1 = size of factory turbo turbine housing nr.1
ft_th2 = size of factory turbo turbine housing nr.2 (=ft_th1)
ft_wg1 = size of factory turbo wastgate nr.1
ft_wg2 = size of factory turbo wastgate nr.2 (=ft_wg1)


nt_th1 = size of new turbo turbine house nr.1
nt_th2 = size of new turbo turbine house nr.1
nt_wg1 = size of new turbo wastgate nr.1
nt_wg2 = size of new turbo wastgate nr.2

ft_th1 = ft_th2 < nt_th1 < nt_th2
nt_wg1 > nt_wg2 >= ft_wg1=ft_wg2

The smaller turbine housed (nt_th1) turbo will spool up sooner than the larger one (nt_th2). The larger turbine house (nt_2) can delivery more air and exhaust gas on high RPM/Load than smaller turbine house (nt_th2). To compensate the difference, the smaller turbine house has larger wastgate (nt_wg1 > nt_wg2) and the larger turbine house has smaller wastgate. In the smaller turbine house on high load some exhaust gas, which cannot flow through the turbine wheel can flow through via the larger wastgate (as the exhaust pressure opens a little bit the larger wastgate).

The problem with the factory turbos is the bottleneck of the exhaust manifold and the relative small turbine house. Depend on application, you can have great results with factory or factory upgraded turbos with the small turbine house and restrictive manifolds, but instead of upgrading them I choose a new PATH based on these ideas and give them a try.

Laszlo

[The Morkinator]

Funny, it cost me nothing but time...

Originally Posted by Sered

I think you misunderstand how much it costs to make a CAST IRON manifold. It requires a mold, which is more expensive to make than even a few tubular manifolds.

If you're talking about two log manifolds; then yes, those are generally cheaper than a tubular; even though they don't flow as well and will limit the torque output. You also have to count that you're buying another turbo, and a single that flows equivalently doesn't cost anywhere near 2x as much. Twin IC piping, twin intakes, etc, etc. It's cheaper to do a single

[Lulz_M3]

Originally Posted by CSL335i

Dear jippii ensio! You point it out well. To be more specific regarding the sizes:

ft_th1 = size of factory turbo turbine housing nr.1
ft_th2 = size of factory turbo turbine housing nr.2 (=ft_th1)
ft_wg1 = size of factory turbo wastgate nr.1
ft_wg2 = size of factory turbo wastgate nr.2 (=ft_wg1)


nt_th1 = size of new turbo turbine house nr.1
nt_th2 = size of new turbo turbine house nr.1
nt_wg1 = size of new turbo wastgate nr.1
nt_wg2 = size of new turbo wastgate nr.2

ft_th1 = ft_th2 < nt_th1 < nt_th2
nt_wg1 > nt_wg2 >= ft_wg1=ft_wg2

The smaller turbine housed (nt_th1) turbo will spool up sooner than the larger one (nt_th2). The larger turbine house (nt_2) can delivery more air and exhaust gas on high RPM/Load than smaller turbine house (nt_th2). To compensate the difference, the smaller turbine house has larger wastgate (nt_wg1 > nt_wg2) and the larger turbine house has smaller wastgate. In the smaller turbine house on high load some exhaust gas, which cannot flow through the turbine wheel can flow through via the larger wastgate (as the exhaust pressure opens a little bit the larger wastgate).

The problem with the factory turbos is the bottleneck of the exhaust manifold and the relative small turbine house. Depend on application, you can have great results with factory or factory upgraded turbos with the small turbine house and restrictive manifolds, but instead of upgrading them I choose a new PATH based on these ideas and give them a try.

Laszlo

EDIT: I just reread what you said, and i dont see how you are going to tune this thing unless you go full standalone. What engine tuning medium are you planning to use? Either way, GL with your endeavors.

[secretsquirrel]

Originally Posted by mj6234

What are the goals here? I am a big believer is outlining expectations and having some sort of objective measurement of success beforehand.

I dont see there being a wide space to fill between something like RBs and the proven single turbo system.

...P.S. I am no vendor fanboi, but I appreciate results when I see them.

I with this guy. I'm having a hard time thinking that this system wont be cost restrictive since it requires a new manifold. The proof is in the pudding though. I'm looking forward to seeing your results.

[Rob@RBTurbo]

CSL335i,

Why you would want the 3 back cylinder "bank" to have a heavier pre-turbine exhaust restriction than the 3 front cylinder "bank" is beyond me? Or am I reading that right? I would want the turbine housings to have the exact same flow capability and also have the wastegate to have the exact same flow capability. Looks like an awesome project but you really aren't thinking that part through too well IMO.

Rob

[CSL335i]

Originally Posted by RobBeck

CSL335i,

Why you would want the 3 back cylinder "bank" to have a heavier pre-turbine exhaust restriction than the 3 front cylinder "bank" is beyond me? Or am I reading that right? I would want the turbine housings to have the exact same flow capability and also have the wastegate to have the exact same flow capability. Looks like an awesome project but you really aren't thinking that part through too well IMO.

Rob

We did similar things on another platform. The reason, why we using two different size of turbine house: to have smaller on, which spool up faster in low rpm and a larger, which can deliver high load. When the smaller turbine house has higher load, than it can handle, a specific part of the exhaust gas, which cannot flow through via the turbine wheel, will escape trough the wastgate. There will be larger pressure in front of the wastegate in the turbine house, then the boost (vacuum), which comes from the acuator and try to stay close the WG. Anyway, at the end we can clearly see how it works, maybe we are on the wrong PATH. The two Garrett speed display gives us important feedback regarding the speed of the wheelsas well.


Laszlo

[jpsimon]

you must be going full standalone then?

[CSL335i]

Originally Posted by jpsimon

you must be going full standalone then?

We would like to stay with OEM ECU with calibrated Cobb maps and JB4 on the top of it. (Currently i have JB4 installed and Cobb, which is not installedd so far).

Wastgates on turbos will be boost actuated (not vacuum) by Garett actuators, or at least we try to fit these things into the OEM architecture. We have some ideas, how we can connect boost actuated Actuators via solenoid control, but we have not tested yet these ideas. If we cannot fit boost actuated Actuators via factory or other solenoids, then we will use vacuum type Forge actuators as a backup plan.

[Sered]

Originally Posted by The Morkinator

Funny, it cost me nothing but time...

Really? If that's the case, why don't you just roll your own kit then?

FYI: A ghetto-fied manifold running weld-els isn't a cast manifold.

[MDORPHN]

Originally Posted by CSL335i

We did similar things on another platform. The reason, why we using two different size of turbine house: to have smaller on, which spool up faster in low rpm and a larger, which can deliver high load. When the smaller turbine house has higher load, than it can handle, a specific part of the exhaust gas, which cannot flow through via the turbine wheel, will escape trough the wastgate. There will be larger pressure in front of the wastegate in the turbine house, then the boost (vacuum), which comes from the acuator and try to stay close the WG. Anyway, at the end we can clearly see how it works, maybe we are on the wrong PATH. The two Garrett speed display gives us important feedback regarding the speed of the wheelsas well.


Laszlo

I take it then that you're contemplating sequential turbos, unlike the stock set-up where each turbo serves a bank of 3 cylinders.

Is this correct?

Neil

[The Morkinator]

Originally Posted by Sered

Really? If that's the case, why don't you just roll your own kit then?

FYI: A ghetto-fied manifold running weld-els isn't a cast manifold.

Two split patterns with a core box would be around $7,000. You would need to cast a type of 02 housing, or exhaust port housing to connect to down pipes, stainless steel, two cover core patterns with core boxes, $5,500. Then you could cast a aluminum y-pipe to get to the intercooler, pattern and core box, $3,500.

The cool thing is ductual iron has a 0% shrink factor so you could just use the model you made in mock-up as the pattern, just go back and add machine stock later when you add you core prints. But aluminum is 5/16 per foot and stainless is 1/4 per foot, so those would just have to be left as models.

Oh ya, then you have to make down pipes, then figure out how to get cool air to the turbos, and tuning.

I'll make you a deal, pay pal me $15,000 as a gift, so I don't pay any fees, and my pattern shop will get right on it. Pony up big boy

[CSL335i]

Originally Posted by MDORPHN

I take it then that you're contemplating sequential turbos, unlike the stock set-up where each turbo serves a bank of 3 cylinders.

Is this correct?

Neil

Two single-scroll turbos with different sizes of turbine house and wastgate compared to each other.

[MDORPHN]

Originally Posted by CSL335i

Two single-scroll turbos with different sizes of turbine house and wastgate compared to each other.

Yes, I get that, But is each turbo serving a bank of 3 cylinders or are they arranged sequentially so each serves all 6?

I presume it's the latter.

Neil

[Lulz_M3]

Originally Posted by MDORPHN

Yes, I get that, But is each turbo serving a bank of 3 cylinders or are they arranged sequentially so each serves all 6?

I presume it's the latter.

Neil

No, its a parallel turbo system.

[MDORPHN]

Originally Posted by Lulz_M3

No, its a parallel turbo system.

OK, I now understand.

Thanks.

Neil

[bryce]

personally, i think the whole "upgraded twins with different turbo manifolds" is not worth it.


*it will be more costly than a big single turbo

*more points of failure or points where issues can arise, from twice the turbo's, twice the downpipes, twice the oil/coolant lines, twice the wastegates, etc.

*single turbo will be more efficient. log manifolds suck and are not as efficient as a properly designed tubular manifold. the upgraded twins will have higher exhaust back-pressure, resulting in higher IAT's, less power, etc.

*you're going to have just as much lag and boost response as the single turbo kit

*a properly sized, single turbo on the n54 won't lag much worse than stock turbo's, as illustrated by FBIS and vishnu's recent threads. look a the dyno's, especially the ones with the stock dyno over-layed onto the single turbo dyno

*twin turbo's will produce much higher torque, which will kill transmissions, axles, etc faster. a single turbo will have more hp than tq, as shown by vishnu's work. twin turbo upgrade will run more torque than vishnu's kit. personally, i wouldn't want more than 500 ft-lbs to the wheels, like the single turbo kit runs

*i'm not just basing this just off vishnu's kit. they're the first with real, quantifiable results. others will fall in over time. a single turbo is better for the n54, all things considered.

[scottp999]

+1 Bryce. I think that for a hybrid twin upgrade there is a nice market, and for a single a nice market, but not much room between them. All we need is the vishnu final kit pricing so people can make a real decision with all the info on what upgrade market they fall in.

[sdstatestud88]

Remember HPFs kit is somewhere in the works haha...Tired of their stupid updates...Full Race I believe is making a kit due next year....Excellent Rep...and there are a couple people working on a twin upgrade project...

Vishnu kit looks good, but will definitely wait till people log thousands of miles as well as what the latter companies have to offer

[CSL335i]

Originally Posted by bryce

personally, i think the whole "upgraded twins with different turbo manifolds" is not worth it.


*it will be more costly than a big single turbo

*more points of failure or points where issues can arise, from twice the turbo's, twice the downpipes, twice the oil/coolant lines, twice the wastegates, etc.

*single turbo will be more efficient. log manifolds suck and are not as efficient as a properly designed tubular manifold. the upgraded twins will have higher exhaust back-pressure, resulting in higher IAT's, less power, etc.

*you're going to have just as much lag and boost response as the single turbo kit

*a properly sized, single turbo on the n54 won't lag much worse than stock turbo's, as illustrated by FBIS and vishnu's recent threads. look a the dyno's, especially the ones with the stock dyno over-layed onto the single turbo dyno

*twin turbo's will produce much higher torque, which will kill transmissions, axles, etc faster. a single turbo will have more hp than tq, as shown by vishnu's work. twin turbo upgrade will run more torque than vishnu's kit. personally, i wouldn't want more than 500 ft-lbs to the wheels, like the single turbo kit runs

*i'm not just basing this just off vishnu's kit. they're the first with real, quantifiable results. others will fall in over time. a single turbo is better for the n54, all things considered.

Regarding the transmission in my case. My DCT will be strenghtened by SSP clutch discs and oil pan will be replaced as well with larger alu one.

During desing, our preferences were:
1, twin-scroll turbine house turbo (like BW EFR) or
two new single-scroll turbo (each for 3 cylinder). I have choosed the second way.
2, One single-scroll turbo is not an option for me, i would not use one big single-scroll on an I6 n54, which does not mean, that somebody cannot fit it and use it.

There are different PATH walk, every PATH has advantages and disadvantages compared to each other.

Laszlo