E90Post
 


The Tire Rack
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > The truth about the N55 engine begins to surface ?



Reply
 
Thread Tools Search this Thread
      01-24-2010, 11:37 AM   #1
cstavaru
Brigadier General
cstavaru's Avatar
308
Rep
3,262
Posts

Drives: 2009 335i M Sport Sedan 6MT
Join Date: Aug 2008
Location: Bucharest, Romania

iTrader: (0)

The truth about the N55 engine begins to surface ?

I just saw this line in the new N55-based BMW 5-series review from Automobile Magazine:

"we sampled a 535i, powered by BMW’s new N55 single-turbo inline six-cylinder. The new engine is rated at the same 300 hp and 300 lb-ft of torque as the outgoing twin-turbo unit, but it doesn’t have quite the same punch at the low end."

http://www.automobilemag.com/reviews...ew_engine.html

Well, now we know why they still use the twin-turbo in the more sports-oriented model...

Go N54 !
Appreciate 0
      01-24-2010, 11:54 AM   #2
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

The differences between the N55 and N54 in the 535i are determined by software specs, not inherent differences in the performance potential of the bi-turbo (N54) versus twin-scroll+valvetronic (N55) designs.

Believe me, there are variants of the N55 in R&D that smoke the current N54 & N54B30.
Appreciate 0
      01-24-2010, 12:18 PM   #3
cstavaru
Brigadier General
cstavaru's Avatar
308
Rep
3,262
Posts

Drives: 2009 335i M Sport Sedan 6MT
Join Date: Aug 2008
Location: Bucharest, Romania

iTrader: (0)

Quote:
Originally Posted by stressdoc View Post
The differences between the N55 and N54 in the 535i are determined by software specs, not inherent differences in the performance potential of the bi-turbo (N54) versus twin-scroll+valvetronic (N55) designs.

Believe me, there are variants of the N55 in R&D that smoke the current N54 & N54B30.
If you ask me, I would say a single bigger turbo can never spool fast enough for low-end torque. A single turbo can be equal, but can never be better than 2 turbos for low-end. Valvetronic does not help much either, because at low RPMs the air volume is low so a throttle plate in the air flow instead of valvetronic doesn't really slow things down. This is where the lack of low-end punch comes from.

Of course, software can bring more additional "punch" but so is the software from GIAC, Evotech, etc. The question is, can it bring the additional punch while keeping the targeted BMW parameters ? If it did (with the current hardware), they would have released it at least in the heavier models like the 535i which would really benefit from more torque.

When I will see an M3 with single turbo and Valveronic I will give the props to N55, but I really believe the next M3 will have a twin-turbo without valvetronic in order to provide low-end torque and a high-RPM redline (where the Valvetronic has problems).
Appreciate 0
      01-24-2010, 12:48 PM   #4
cotmfk
Major General
cotmfk's Avatar
2024
Rep
6,093
Posts

Drives: M3
Join Date: Mar 2009
Location: Somewhere between DC and FL

iTrader: (12)

Lag can be fun, though... like when all of a sudden 30 psi hits!

But, for everyday driving, not so much. Two twin scroll turbos as an upgrade option to the N54 might be something to look at. Two bigger turbos, but twin scroll to try and help alleviate low end lag.
__________________
When you say impact instead of affect/effect, you are communicating that you don't understand the difference between the two words, and are too lazy to learn.
Appreciate 0
      01-24-2010, 12:55 PM   #5
Sniz
Lieutenant General
Sniz's Avatar
648
Rep
10,587
Posts

Drives: e92 335 - gone // e36 M3 turbo
Join Date: Mar 2007
Location: Ellicott City, MD

iTrader: (1)

I would expect the n55 to have a little less low end grunt, but be surperior up top where it really helps for performance reasons.

a n54 powered vehicle can certainly pull my M3 on low end rpm pulls, but once i'm spooled, good bye.

same idea but the n55 wont be as laggy as a larger turbo for many reasons, twin scroll and valvetronic being 2 of the main ones.
__________________
Appreciate 0
      01-24-2010, 01:05 PM   #6
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

Quote:
Originally Posted by Sniz View Post
I would expect the n55 to have a little less low end grunt, but be surperior up top where it really helps for performance reasons.

a n54 powered vehicle can certainly pull my M3 on low end rpm pulls, but once i'm spooled, good bye.

same idea but the n55 wont be as laggy as a larger turbo for many reasons, twin scroll and valvetronic being 2 of the main ones.
Avoidance of lag has always been a top priority for BMW for these bread&butter cars. Twin scroll is another way of getting boost at low rpm/pressure -- a small impeller with little inertia, and then a big one for serious boost (like the turbo in the diesel). The twin turbo design did much the same -- little turbos spin quickly, two turbos push more air.

Edit: misuse of term "impeller", see comments below.
Appreciate 0
      01-24-2010, 01:08 PM   #7
Tee212
Banned
United_States
79
Rep
4,541
Posts

Drives: yes
Join Date: Oct 2008
Location: Riverside

iTrader: (9)

Garage List
2010 335  [8.00]
always trade offs
Appreciate 0
      01-24-2010, 01:35 PM   #8
cstavaru
Brigadier General
cstavaru's Avatar
308
Rep
3,262
Posts

Drives: 2009 335i M Sport Sedan 6MT
Join Date: Aug 2008
Location: Bucharest, Romania

iTrader: (0)

Quote:
Originally Posted by stressdoc View Post
Twin scroll is another way of getting boost at low rpm/pressure -- a small impeller with little inertia, and then a big one for serious boost (like the turbo in the diesel).
Sorry but this is not true. Twin-scroll just means that exhaust gases (from the six cylinders in this case) are split in two separate streams of flow (one flow from each 3-cylinder bank) which enter the turbine separately and spin the same impeller which has two sets of fins, one for each flow. The advantage is the higher pressure in each flow and the alternating exhaust pulses in each flow path (after a cilinder fires the exhaused gas from that cylinder creates and exhaust "pulse") which create the high turbine RPM faster than a single flow.
Appreciate 0
      01-24-2010, 01:57 PM   #9
bimmerboy
Captain
bimmerboy's Avatar
23
Rep
601
Posts

Drives: 135i
Join Date: Jan 2009
Location: Bay Area

iTrader: (0)

Quote:
Originally Posted by stressdoc View Post
Twin scroll is another way of getting boost at low rpm/pressure -- a small impeller with little inertia, and then a big one for serious boost (like the turbo in the diesel)...

Sorry but you are wrong.
Read here from BMW: Twin Scroll Turbo System Explained
Quote:
Twin-scroll turbo system design addresses many of the shortcomings of single-scroll turbo systems by separating those cylinders whose exhaust gas pulses interfere with each other. Similar in concept to pairing cylinders on race headers for normally aspirated engines, twin-scroll design pairs cylinders to one side of the turbine inlet such that the kinetic energy from the exhaust gases is recovered more efficiently by the turbine. For example, if a four-cylinder engine’s firing sequence is 1-3-4-2, cylinder 1 is ending its expansion stroke and opening its exhaust valves while cylinder 2 still has its exhaust valves open (while in its overlap period, where both the intake and exhaust valves are partially open at the same time). In a single-scroll or undivided manifold, the exhaust gas pressure pulse from cylinder 1 is therefore going to interfere with cylinder 2’s ability to expel its exhaust gases, rather than delivering it undisturbed to the turbo’s turbine the way a twin-scroll system allows.
The result of the superior scavenging effect from a twin-scroll design is better pressure distribution in the exhaust ports and more efficient delivery of exhaust gas energy to the turbocharger’s turbine. This in turn allows greater valve overlap, resulting in an improved quality and quantity of the air charge entering each cylinder. In fact, with more valve overlap, the scavenging effect of the exhaust flow can literally draw more air in on the intake side while drawing out the last of the low-pressure exhaust gases, helping pack each cylinder with a denser and purer air charge. And as we all know, a denser and purer air charge means stronger combustion and more power, and more power is good!
But the benefits of twin-scroll design don’t end there. With its greater volumetric efficiency and stronger scavenging effect, higher ignition delay can be used, which helps keep peak temperature in the cylinders down. Since cooler cylinder temperatures and lower exhaust gas temperatures allows for a leaner air/fuel ratio, twin-scroll turbo design has been shown to increase turbine efficiency by 7-8 percent and result in fuel efficiency improvements as high as 5 percent.
Just tired of people spreading mis-information....
__________________
--2009 BSM 135i--
-Manual, Sport Package, BMW Assist
Appreciate 0
      01-24-2010, 02:07 PM   #10
GreenPlease
Lieutenant Colonel
GreenPlease's Avatar
United_States
129
Rep
1,629
Posts

Drives: BMW 335i e92
Join Date: Feb 2008
Location: Orlando Florida

iTrader: (2)

[quot]But, for everyday driving, not so much. Two twin scroll turbos as an upgrade option to the N54 might be something to look at. Two bigger turbos, but twin scroll to try and help alleviate low end lag.[/quot]

two twin scrolls on any six cylinder engine makes zero sense. It would actually be significantly less efficient. The whole point of a twin scroll turbo is to seperate the pulses of exhaust gas.
__________________
Cars>Women
Appreciate 0
      01-24-2010, 02:11 PM   #11
DJKhan85
Major
DJKhan85's Avatar
Trinidad_and_tobago
24
Rep
1,190
Posts

Drives: 2011 4dr 6mt Golf GTI
Join Date: Jun 2009
Location: Boston Massachusetts

iTrader: (1)

^ aren't they putting dual twin scrolls in the next M3 engine(I6)? Is that just forum banter at this point?
__________________
2011 VW GTI 4dr-6mt-Sunroof-Nav-Xenons
OLD:
08 335i AW/CR/Poplar 6mt-ZSP-ZPP-ZCW-iPod-iDrive-PDC-Style 230s w/FK 452-Dinan LSD
Appreciate 0
      01-24-2010, 02:46 PM   #12
cstavaru
Brigadier General
cstavaru's Avatar
308
Rep
3,262
Posts

Drives: 2009 335i M Sport Sedan 6MT
Join Date: Aug 2008
Location: Bucharest, Romania

iTrader: (0)

Quote:
Originally Posted by DJKhan85 View Post
^ aren't they putting dual twin scrolls in the next M3 engine(I6)? Is that just forum banter at this point?
No way. For dual twin-scroll you would need to create 4 "equal" streams of flow but you have 6 cylinders...so you can't

It will either be a twin-turbo I6 (my guess is 3.2-3.6 liters) or a twin-scroll, twin-turbo V8.
Appreciate 0
      01-24-2010, 03:07 PM   #13
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

You guys are right of course -- the turbo in the N55 is not a sequential design, nor an active variable geometry design. I should always double check myself whenever I use the word "impeller" because I use it inappropriately to refer to the turbine fan. My point is simply that the turbine fans in the N55 are designed for low threshold, reduced lag, and high power. I don't understand the nuances of how the blades are designed differently to take advantage of the separated manifold.

Pretty good summary here:
http://kilometermagazine.com/artman2...Turbo_Six.html

But I want to see a better cutaway than what BMW provided in the Press package.

Any advantages to a manifold/header divided 6 ways, with separate inputs from each cylinder to the turbo? Complicated mess.
Appreciate 0
      01-24-2010, 03:35 PM   #14
supracg
Banned
7
Rep
320
Posts

Drives: 135i
Join Date: Mar 2009
Location: potomac

iTrader: (0)

If the n55 can create more power at the high rpms, why does the iS essentially have the n54 engine?
Appreciate 0
      01-24-2010, 04:15 PM   #15
TwinTurboXI
Lieutenant Colonel
158
Rep
1,523
Posts

Drives: 2011 135i
Join Date: Mar 2008
Location: .

iTrader: (12)

Quote:
Originally Posted by Nick.CBR View Post
Please expand on this. That's a pretty wild statement to make without citing your sources.

Nick
+1
Appreciate 0
      01-24-2010, 04:38 PM   #16
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

What is so "wild" about BMW R&D having multiple engine versions? They always do. Most obviously never make it to market. Second point, if you have people that you know inside BMW you don't name them. Third point, I don't write about stuff here unless it's already out, in this case Michael (Mapezzul) discussed N55 variants on his blog.
Appreciate 0
      01-24-2010, 05:27 PM   #17
cstavaru
Brigadier General
cstavaru's Avatar
308
Rep
3,262
Posts

Drives: 2009 335i M Sport Sedan 6MT
Join Date: Aug 2008
Location: Bucharest, Romania

iTrader: (0)

Quote:
Originally Posted by stressdoc View Post
What is so "wild" about BMW R&D having multiple engine versions? They always do. Most obviously never make it to market. Second point, if you have people that you know inside BMW you don't name them. Third point, I don't write about stuff here unless it's already out, in this case Michael (Mapezzul) discussed N55 variants on his blog.
What's the blog address of Mapezzul ? He seems very knowledgeable...
Appreciate 0
      01-24-2010, 05:32 PM   #18
JakeN5
Second Lieutenant
United_States
6
Rep
257
Posts

Drives: e90 328i LCI
Join Date: Sep 2009
Location: SoCal

iTrader: (0)

lag or no lag, I'd still go for the N55 just because it's a newer toy, then patiently wait for the tuners to do their tricks. On top of that, the possibility that the N55 may be a more dependable unit more than makes up for its shortcomings.
Appreciate 0
      01-24-2010, 06:26 PM   #19
cn555ic
cn555ic's Avatar
United_States
441
Rep
18,331
Posts

Drives: 335i
Join Date: Jun 2007
Location: US

iTrader: (6)

Quote:
Originally Posted by JakeN5 View Post
lag or no lag, I'd still go for the N55 just because it's a newer toy, then patiently wait for the tuners to do their tricks. On top of that, the possibility that the N55 may be a more dependable unit more than makes up for its shortcomings.
Well everything that comes out seems to be the best thing out, we will wait and see what the N55 platform brings, but I have a feeling the N54 will be a special engine that enthusiast will be looking for a long time after its no longer in production...If it wasn't anything special why would they even offer it in the 335is model, knowing that the enthusiast would pay top dollar for a N54 engine..
Appreciate 0
      01-24-2010, 06:52 PM   #20
scheherazade
Major
36
Rep
1,467
Posts

Drives: 09 GTR (& 93' accord!)
Join Date: Sep 2008
Location: DC metro area

iTrader: (8)

Quote:
Originally Posted by supracg View Post
If the n55 can create more power at the high rpms, why does the iS essentially have the n54 engine?
for the average joe, 'twin turbo' sounds better than 'turbo'.

how many people do you know that would drive a more laggy vs less laggy car, and say the more laggy car is more sporty...

hardly anyone spends any time over 6000 rpm. And the car isn't marketed towards the serious performance crowd (more like the 'ooh, sporty sounds nice!' crowd).

-scheherazade
Appreciate 0
      01-24-2010, 06:56 PM   #21
5soko
Brigadier General
5soko's Avatar
332
Rep
4,632
Posts

Drives: M5
Join Date: Aug 2007
Location: Brooklyn, NY

iTrader: (4)

The newest isnt always the greatest. That goes for both tuning potential greatest and daily driving consumer greatness.

The N55 seems to be and have less tuning potential than the N54 because of the valvetronic, and of course it going to come with some tough anti-tuner hardware/software mix that will most likely keep tuning power levels at bay.

For everyday driving, the N55 has the stuff to make it really good. If and how much better than the N54 we will have to see, tq coming in 500rpm early is going to be hard for alot of people to see a difference in there dail driving, so we will have to see, i expect to test drive one as soon as it comes out at my local dealer.

Tuning wise, the N54 is going to be the better choice. since there is more R&D which is 3 years into it if not longer which is major.

All we can do is speculate but tuning wise things are really leaning on the N54 side.
Daily driver and out of the box wise, the N55 has the right stuff but if it will be better we will have to see.
Appreciate 0
      01-24-2010, 11:47 PM   #22
Spool
******
Spool's Avatar
Vietnam
555
Rep
6,169
Posts

Drives: A few
Join Date: Apr 2007
Location: DC Metro

iTrader: (24)

you guys are complaining about a little turbo lag...my shit spools at 5000 RPM...LOL
__________________


MKIV 6spd 1000hp Club
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 06:10 PM.




e90post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST