astroboy;727138 said:
The earlier 335i was using N54 twin turbo. The main purpose for twin turbo is to eliminate turbo lag, a small turbine kicks in first before the huge turbine engages to ensure smooth delivery of power.
The 320d is using twin scroll single turbo to achieve the twin turbo objective. Same as the one in N54 decedent, the N55 for the later E92 335i and this F30 335i.
Single turbo suffers turbo lags badly and not suitable for a premium Euro marque like this.. :4:
Actually the N54 has similar size twin turbos. N55 single turbo but twin scroll. Twin scroll means twin intake pipes separately chanelling exhaust gases (one for cylinder 1,2,3 and the other for 4,5 and 6) onto the exhaust turbine fan which is connected to the inlet fan that compresses incoming air. By virtue of separating the exhaust gases travelling at high speed into 2 separate channels, this minimises turbulence (due to engine's firing order, if I remember correctly for inline siz engine its 1-5,2-6,3-4) and create a smoother flow which translates to lesser/minimal turbo lag.
supersonic;727141 said:
Thanks Paul & Astroboy. Now I see the picture. The N47 was allthe time twin scroll. Just that it was not highlighted in the spec sheet for my e90.
In the F30 320D , they just mention twin power engine with a turbocharger, while in the 328 they say twin power engine with twin scroll turbo.
Yeah, this is the fault of the marketing people inventing fancy acronyms
If I may confuse everyone further, in BMW world Twin Power Turbo could mean 3 things, namely:-
1) Twin Turbo Units (as in the N54 engine with same size turbine)
2) Twin Turbo Units (one small and one larger turbine, as in the 525d)
3) Single Turbo with Twin Scroll (320d, 328i, 335i and etc etc)
Test drove the F10 525d in a far away race track recently, all I can say is :rock: . This engine needs Euro 4 diesel.
Cheers
