2011 135i with 6 Auto Gearbox!!!

[hossamk]

Dear All

this is my first thread, i am looking for buying a BMW 135i and it is very rare here in Qatar where i live currently. i found a very nice one for sale but strangely it has the normal 6 speed Auto and not the new Dual Clutch.

does it make a big difference in performance or both are okay? and how can i know from looking under the hud that the engine is N45 or N55?

thanks

[RaihaX]

if you google n54 and n55 on google image you will see the difference.

The N55 will have something like Twinpower or twinscroll (can't remember) on the engine cover.

[hossamk]

Thank you, the N55 have a big Twinpower Turbo on its bonnet can't miss it.

any thoughts on the gearbox?

[RaihaX]

the DCT is faster for sure but then you get the crappy N55

[ParkNuts]

Originally Posted by RaihaX

the DCT is faster for sure but then you get the crappy N55

I can't wait for a new aftermarket twin scroll to come into play that simply bolts up to the N55 to make all the N54 guys jealous. N55 isn't crappy. It's simpler, less problematic and torquier, even when both are tuned.

[3VOM]

Originally Posted by hossamk

Thank you, the N55 have a big Twinpower Turbo on its bonnet can't miss it.

any thoughts on the gearbox?

If the car you are talking about has an N55 (twin power turbo) with the regular 6 sp auto...that is wierd. I bought the the N55 over the N54 for the sole reason that it came with the DCT. Fantastic tranny. The standard auto isn't bad...just not the same...the ONLY reason I would think about the 6sp auto over the DCT is because of the N54. Before I put my flame suit on to protect myself from the folks that like to manually row the gears...I need to have a car my wife can also drive...she doesn't drink...I do! Haha. But to be honest I now prefer the DCT or most dual clutch trannies over manuals.

[Dackelone]

N54...




N55...




DCT...

6AT...



stock, the n55 spools up faster and is slightly better with fuel. The N54 was under rated from the get go... so many people think it makes far more than the 300 Hp (SAE) it is rated at.

Tuned a N54 will make over 400 Hp easy. A tuned N55 will only make around 360 Hp, bc its internal parts are not forged like the N54 motor.

DCT will shift MUCH faster than the 6AT.

You need to decide which engine and trans is best for you!

[chopper817]

Originally Posted by ParkNuts

I can't wait for a new aftermarket twin scroll to come into play that simply bolts up to the N55 to make all the N54 guys jealous. N55 isn't crappy. It's simpler, less problematic and torquier, even when both are tuned.

i also want to see a replacement turbo for the n55 that will flow more air at a higher volume so the n55 can reach its potential.

i will have to disagree on the part you said about being "simpler". if anything valvetronic makes it much more complicated. each of the valves for each cylinder work independently and replace the need for one throttle body. its a more advanced version of the e46 m3 intake system with a throttle body for each cylinder.

[chopper817]

Originally Posted by Dackelone

stock, the n55 spools up faster and is slightly better with fuel. The N54 was under rated from the get go... so many people think it makes far more than the 300 Hp (SAE) it is rated at.

Tuned a N54 will make over 400 Hp easy. A tuned N55 will only make around 360 Hp, bc its internal parts are not forged like the N54 motor.

DCT will shift MUCH faster than the 6AT.

You need to decide which engine and trans is best for you!

thats not the reason a n54 with a tune makes a little more power than n55 with an equal tune from the same company...

forged internals dont "add" power all by them selves..its because the small twins flow a little more air while staying in its efficiency range than the larger twin scroll can....

[ParkNuts]

Originally Posted by Dackelone

N54...


stock, the n55 spools up faster and is slightly better with fuel. The N54 was under rated from the get go... so many people think it makes far more than the 300 Hp (SAE) it is rated at.

Tuned a N54 will make over 400 Hp easy. A tuned N55 will only make around 360 Hp, bc its internal parts are not forged like the N54 motor.

DCT will shift MUCH faster than the 6AT.

You need to decide which engine and trans is best for you!

I don't think I've ever seen any proof that the N54 had forged internals, only a lot of back and forth with no concrete evidence. If anything, it was the crank, and with regard to that I heard something along the lines of "with a naturally balanced engine, breaking a crank is the last thing you need to worry about." So it would make the difference pretty minimal. And it seems like the N54's are holding up just fine to the amount of power people are getting out of them without forged pistons. I'd like to think the N55 will be fine at moderate power levels (below 500rwhp). I don't want to go north of that, so the forged issue becomes less profound.

[rader1]

N54 internals are forged. The cranks and rods atleast. The pistons are not(or atleast almost all of them are not.)

Internal component failures are usually the results of poor tuning or other external factors(oil dillution, mechanical over, etc..) However, the MSD80/81 is DAMN good at saving the engine and the fact that there have been so few cars running the JB that have grenaded engines is a testament to this.

The N55's twin scroll is just to small to sustain flow at the revs needed to make big power. With an upgraded turbo the N55 or N54 will make just as much power as anyother FI 3 liter I-6.