[CoolDude196]

is the engine in the 125i the same 2.0l thats in the 328i, just with less power output?
or is the 125i just single turbo, compared with the 328i's twin turbos?

cheers

[clarence]

Depending on batch or production date, it could either be 100% identical apart from engine mapping or there could be a different turbo or some either minor difference in parts used.
328i uses a single twin-scroll turbo. It isn't twin-turbo.

[CoolDude196]

Originally Posted by clarence

Depending on batch or production date, it could either be 100% identical apart from engine mapping or there could be a different turbo or some either minor difference in parts used.
328i uses a single twin-scroll turbo. It isn't twin-turbo.

cheers mate... didnt realise it wasnt twin turbo

[SomeRandomer123]

Originally Posted by Cool_dude196

cheers mate... didnt realise it wasnt twin turbo

Yep just different mapping I think...
And they both have a Twin Scroll turbo, meaning twin turbo power, but from a single turbo, so it's all good!

[CasZy NL]

2012 versions are the same engine. The 328i has 245hp, the 125i has 218 hp.

[Naambezet]

Originally Posted by CasZy NL

2012 versions are the same engine. The 328i has 245hp, the 125i has 218 hp.

And the 20i versions also have the same engine, but with 184 hp

[CoolDude196]

Blimey, such different power outputs from effectively the same engine.
I'd love to know how the twin scroll turbo works, very clever piece of tech!
Thanks for the response

[E90Fleet]

Originally Posted by Naambezet

And the 20i versions also have the same engine, but with 184 hp

There are actually a number of different 20i engines depending on model and country.
They vary on compression ratios and turbo's

[KneeDragr]

Originally Posted by Cool_dude196

Blimey, such different power outputs from effectively the same engine.
I'd love to know how the twin scroll turbo works, very clever piece of tech!
Thanks for the response

http://www.modified.com/tech/modp-09...n/viewall.html

[ATX78703]

Originally Posted by KneeDragr

http://www.modified.com/tech/modp-09...n/viewall.html

Fantastic article link. When you read this, you kind of understand why the N55 is a generation ahead of the N54. The N55 has near zilch lag and peak torque at 1250. What BMW is bringing to both low end and high end game, audi and MB will not be able to compete. You gotta understand BMW is keeping the engines tuned down for gas mileage purposes also.

Bolting on a roots-type supercharger in a V-bank on a 6 cylinder (read Audi S4) is nothing groundbreaking and runs off the belt power anyway. When BMW opens up the exhaust and compression a little on these twin-scroll models, it will destroy these other FI competitors.

This is my favorite line from that article "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." Essentially optimizing your twin-scroll to your cylinder firing sequence basically creates a vaccuum to increase your intake flow. awesome.

[RPM90]

Originally Posted by ATX78703

Fantastic article link. When you read this, you kind of understand why the N55 is a generation ahead of the N54. The N55 has near zilch lag and peak torque at 1250. What BMW is bringing to both low end and high end game, audi and MB will not be able to compete. You gotta understand BMW is keeping the engines tuned down for gas mileage purposes also.

Bolting on a roots-type supercharger in a V-bank on a 6 cylinder (read Audi S4) is nothing groundbreaking and runs off the belt power anyway. When BMW opens up the exhaust and compression a little on these twin-scroll models, it will destroy these other FI competitors.

This is my favorite line from that article "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." Essentially optimizing your twin-scroll to your cylinder firing sequence basically creates a vaccuum to increase your intake flow. awesome.

The N55 is truly a modern turbo engine, and is one heck of an engine.
But, in terms of power output the N54 is better. Even the latter N54's had a bit more power than the N55 does, and it's been confirmed by quite a number of dyno runs. Go to the 135i forum or the E90 335i forum and you'll see there is a difference in power output.

BMW claims the N55 builds it's torque sooner, but in reality it's very minor. I too had high hopes for the N55 with it's valvetronic intake.
I thought that with this setup it would allow better and greater high rpm power creation. Unfortunately that did not happen in stock form, and it's mainly due to the small size of the single turbo.

Twins scroll is a great idea, and would have been even better in the N55 if BMW would have put in a larger twin scroll. As it is I believe the air flow rate of the 2 smaller turbos in the N54 have a slightly greater capacity than the slightly larger single twin scroll, and that that is the reason why tuners have had greater success in building more power with the N54 than with the N55.

Still, I hold hope that the tuners will get better at programming the valvetronic and be able to use it in a greater capacity than they do now.
After all, by not having a throttle plate, valvetronics immediate benefit is is less pumping loss as the engine tries to breathe against a restrictive plate, which valvetronic doesn't have. So I am surprised that the N55 stock was not as powerful as the N54 with it's more traditional intake.

Don't sell Audi's 3.0 SC short. It's one heck of a modern SC engine.
It's powerful, quite in cruise, and has excellent throttle response that is better than either N54 and N55.
Audi's SC engine doesn't whine like typical SC applications, and puts out comparable power to either N54/N55. It's biggest fault is it's MPG, but it was more in line with the E90 335i. The new F30 335i has better MPG, mostly due to the new 8spd auto, which has 2 over drive gears, and that's where the 3 is getting it's biggest boost in MPG.

Overall though, BMW's 3.0 is more fuel efficient when running normally mostly due to not having the parasitic drag of the SC's drive belt.
I say "normally" because if you push the engine to give you 300hp, then it still costs in fuel and nearly the same quantity of fuel whether turbo or supercharged.
The best thing about the SC's V6 is it's throttle response, it's there when you ask for it. As little turbo lag as BMW's N54 and N55 have, in comparison to the SC V6, their lag shows up when you drive the S4 back to back with the E90 N55.

BMW's new N20 is quite an impressive little turbo. It has better throttle response than my N54 and better than the N55 in my experience in driving them. It's really quite amazing how quickly that little engine responds.
And, it's putting out some very generous power as evidenced by recent dyno testing. Here's an interesting article on that:
http://www.automobilemag.com/feature.../photo_05.html

That dyno run shows 222hp and 245lb ft at the wheels.
BMW rates it at 240hp and 260lb ft at the crank.

From those dyno numbers, if we use a low drive train loss of 10%, torque at the crank is more like 273lb ft. If we use 15%, then torque at the crank is more like 287lb ft!

At the BMW rated torque of 260lb ft, at a 10% loss wheel power should be around 234lb ft. At a 15% loss, wheel torque should be around
221lb ft. The N20 is pretty amazing.

HP is BMW rated at 245hp. At a 10% loss, wheel HP should be around 220hp.
At 15% loss, wheel HP should be around 208hp.
That dyno shows HP at 222hp.
At a 15% loss, real crank HP is around 260hp!

Automatic's average drive train loss is around 20%.
Manuals average loss is around 15%.
Using 15% power train loss, the N20 power at the crank is more like
260hp and 287lb ft. NICE!

[CoolDude196]

Originally Posted by KneeDragr

http://www.modified.com/tech/modp-09...n/viewall.html

cheers for that

[lukeb817]

Edmunds InsideLine dyno testing showed 240hp at the wheels. Pretty impressive.

[CoolDude196]

Originally Posted by E90Fleet

There are actually a number of different 20i engines depending on model and country.
They vary on compression ratios and turbo's

That would work well for bmw i suppose, if they're based on the same engine..