[Pepe_pr]

Originally Posted by berserkerx

spam much? lol

Stupid iphone app was showing an error and i tried to post and showed the error again but apparently it posted!!!

Sorry for the "spam"

[berserkerx]

haha my phone has done that before. not on this forum though. I just had to give you shit.

[Dieselmd]

Originally Posted by shockin330i

What people tend to forget is that a twin scroll turbocharger isn't meant for big power up top. Twin scrolls like ours are meant for good low end tq. Granted a bigger turbo will yield better results.

Care to educate us on why Twin-Scroll turbos aren't designed for big power up top?

[Slops]

Originally Posted by Dieselmd

Care to educate us on why Twin-Scroll turbos aren't designed for big power up top?

interested as well...

[shockin330i]

Originally Posted by Dieselmd

Care to educate us on why Twin-Scroll turbos aren't designed for big power up top?

This is a wonderful read for anyone
http://www.full-race.com/articles/efrturbotechbrief.pdf

But this is the section about twin vs single

Let’s pause on the EFR housing descriptions and spend a few moments
on the subject of twin-scroll (divided) turbine housings. Twin-scroll
housings are becoming very popular for performance use, and for good
reason. By dividing the manifold and turbine housing into two flow
paths, the engine firing order can be made to “alternate” the flow all the
way to the turbine wheel inlet. The engine blow-down pulse is
generated when the exhaust valve opens. During the blow-down, the
engine power cylinder is still at very high pressure as a residual of
combustion and the power stroke. This initial “pop” of energy travels
at very high speed down the manifold runner, through the volute, and
impacts the wheel. For this reason, the stream is very much a “pulsed
flow” and the divided nature of the system simply amplifies and
arranges those pulses. The engine firing order creates a “one-two”
(alternating) punch on the wheel, keeping the pulses evenly spaced and
in rapid succession. As the engine speed increases, this becomes a blur
and the alternating nature loses its value. Hence, twin-scroll housings
only benefit the low and medium speed operation of an engine. Within
this range, it is a very effective way to improve turbine effectiveness.
The wheel loves the high velocity evenly-spaced pulses of gas, and as
21
long as they are “slow” enough in succession and duration, the wheel
can make good reaction usage of the energy. What results is an
improvement in “effective” efficiency, and at lower engine speeds more
turbine power can be generated. The obvious result is quicker spool
and better low-end boost response. As mentioned, the top-end
operation is not improved, everything else being equal. Put into
practice, a single-scroll housing of sufficiently large size is the recipe for
a user that is seeking only top-end power optimization. That said, a
very potent combination is a twin-scroll divided system that works to
retain good low speed boost response, while sizing it large
(aerodynamically) for the best top-end power. It’s the best of both
worlds, in many cases.

[shockin330i]

Originally Posted by boosted335

hey shockin330 try to reset Ur proceeded...I had same issue wit bms jb4 Ur was over boosting.do u know ur boost levels at certain rpms. like bms custom tuning....u might just have turn down the boost little

I'll check it out.

[turugara]

Originally Posted by shockin330i

This is a wonderful read for anyone
http://www.full-race.com/articles/efrturbotechbrief.pdf

But this is the section about twin vs single

That makes sense. Thanks for linking.

[Dieselmd]

I m certinly not an engineer or an expert of any kind but, newer turbo-technology ie ultra strong and light turbine wheels and super efficient compressor wheels will change how consumers view twinscroll vs single turbos in the future. Again, I am not an expert but I, like the rest of you have read my socks off trying to understand why one MAY be better than the other. Once Full-Race becomes more active in the BMW community, Geoff will certainly add his vast knowledge here and educate us all a bit more.

[Slow_335i]

OP good luck and keep us posted as you make progress

[berserkerx]

I am currently trying to convince Geoff to be a vendor on the forums. That way he can officially come and speak for himself. I don't want to offend the mods myself and I know Geoff doesn't either.

on the topic of twin scroll BMW has moved to it. I believe ford has as well, Mitsubishi has used them for a long time. maybe we should just use a turbo like what comes on the newer ford with dual compressor wheels lol.

but from all I have read twin scroll is all about wide power band. not an ultimate power turbo.

[Slops]

Thanks for the good read! My take is to size the turbo large enough to hit the top end that you want. Being twin scroll doesn't mean you can't make serious power up top while spooling up quick down low. Like the article said... Best of both worlds

[bojanglos]

You are correct in saying that the advantage of the Twin Scroll is you can use the opposing pulses to spool a bigger compressor faster. The problem with turbo sizing is that you can move massive air very fast on the compressor side but then cork the whole system up on the exhaust side. The concept of the twin scroll is too speed up the spool yet still allow big enough wheels to get the exhaust out. That is one of the reasons that I believe BMW switched to a twin scroll. The previous twins allowed more air. I have reasoned that the BMW doesn't really care about massive power at the top end. They made this car to have x amount of power and what they engineered does this. The other problem that the manufacture has is modded cars switched back to claim warranty. So if you limit the amount of air that can flow through the engine by limiting the size of the turbo you also limit the aftermarket from pushing the engine beyond its limits.
To go beyond these limits you have to mod the car enough that a warranty void is going to be obvious. The stock crank is rumored to be cast not forged so using the turbo as a cork seems like a good limiter to me. I wonder how many true performance minded individuals who are on this forum are actually willing to completely void the stock warranty and will actually do it knowing they have no warranty and not try and trick the dealer to get service when they have problems. I havn't owned a new car in 10 years that hasn't had the warranty voided by 1500 kms. This car will be no exception. When something breaks and I do mean when I replace it with something stronger. So to sum this up without a mass amount of people willing to void warranties seeing new big single options are not worth the aftermarket developing. I don't think that I will be using a JB4 on my car as I want full control and the only way I see that is with complete ECU re-flash. So that will be what holds me up but we will see what happens ECU wise shortly.

Cheers Bo J

[Tony135]

Some good reading in here! I love the activity. Let's keep it up so we can get what we all want!

[Shamim]

just curious, im not that educated in turbos but I know little things here and there. I am in the market for a 335 but getting a bit worried if i want to go with the n54 or n55.

Lets just say a 335 with the n55 engine having a charge pipe, intercooler, downpipes, intake, meth, no cats but a good muffler, and a ecu tune. What numbers are expected (generally ofcourse) and what boost can you put out from the turbo. Will it break the crank shaft?

[bojanglos]

Can anyone actually verify( not I read I heard) but has actually seen a crank break. See I would be skeptical of that being that the engine is an Inline 6. Cast crnks were used for years yes not as good as forged but they have their advantages as well. If you have seen one lets get some pictures and what actually caused the crank to break.

[Tony135]

Originally Posted by Shamim

just curious, im not that educated in turbos but I know little things here and there. I am in the market for a 335 but getting a bit worried if i want to go with the n54 or n55.

Lets just say a 335 with the n55 engine having a charge pipe, intercooler, downpipes, intake, meth, no cats but a good muffler, and a ecu tune. What numbers are expected (generally ofcourse) and what boost can you put out from the turbo. Will it break the crank shaft?

I have all of that minus the intake which doesn't do much anyway. I haven't dynoed recently since I fixed everything but it should be around 380whp and 430tq

[shivaswrath]

Originally Posted by Tony135

I have all of that minus the intake which doesn't do much anyway. I haven't dynoed recently since I fixed everything but it should be around 380whp and 430tq

Did anyone finally uncover specs on the N55 turbo?
Is it updated in the F30?

i'm trying to sort out whether an FMIC is worth the cost or not...

[Andrewe92]

OP whats the need for all that power damn ahah

[melloww22]

Originally Posted by missilewarriorz

OP whats the need for all that power damn ahah

Wow 16 months old post... N55 turbo R&D just got some time in the sun since stage 2 turbo upgrades for n54 have been completed...

N55 turbo upgrade won't be a reality for at least 18 more months... Too expensive and low level of support from builders...