[Grizz258]

I know what the difference is between the turbos. I'm just wondering if one is more sufficient than the other? I drive a 09 e90 335i. Ive heard its more efficient and I've heard doenst matter. Just needed more opinions.

[Rockette]

Bi = 2

Twin = 2

Therefore: Bi = Twin

[thai357sig]

Does it have anything to do with sequence as in parallel or series?

[Ginger_Extract]

I have always heard of twin turbos (N54) as being in-parallel, and bi-turbo (a la FD RX7) as being in-series. I'm not sure it really matters either way you splice it, it's just different terminology...

[ybbiz34]

BMW prefers to use "twin turbo" nomenclature when referring to a motor utilizing two turbochargers.

Mercedes, on the other hand, prefers the "biturbo" nomenclature.

Both references basically mean the same thing but separate labels help to distinguish the brands when the terms are used to describe each brand's respective motor setup/technology.

[yousefnjr]

Just a guess, twin sounds like it was maybe a colloquialism that caught on and stuck, like Bimmer or Lambo

Bi-turbo sounds more technically accurate... Germans

[Twix]

I always thought that twin meant two turbos that feed a single intake plenum, and bi meant that each turbo fed its own plenum

[Red Bread]

I assume the confusion here is just in wording. N54 = twin turbo. N55 = twin scroll single turbo. As stated earlier, for twin turbos, there's also the issue of whether they work in series or parallel.

[Raja Ventureshield]

sequential twin turbo is better I think as one spools up while the othe is kicking it. That way you have continuous momentum build up vs. plateau.

bi = twin are the same.
n54 is twin turbo
n55 is twin scroll single turbo

n54 is more tunable from what i heard, but i could be wrong. the last time my sister had Supra Turbo - we blew the turbo by running it too hot. :-(

[BavarianN54]

BMW is partially responsible for much of the confusion. When they named their N55 ' twinpower' it confused many. I also think it was intentional, to let customers believe the new engine was still a twin turbo layout.

[Thumperx]

I cannot believe this subject is being discussed (????).

[smellfish]

Bi is always better regarding cars and women

[Holygrail]

I always thought that twin-turbos were two turbos of same size, which spooled up at the same rate and rpm, and bi-turbos two turbos of different sizes that spooled up at different rpms. For example, on the bi-turbo, one turbo would kick in earlier at the lower rpm and the other at a higher rpm to eliminate turbo lag. In order to make engines more efficient and to eliminate turbo lag, the Japanese had engines with both supercharger and turbocharger; the supercharger activates at lower rpms and the turbos would kick in at higher rpms ensuring constant power range.

I could be wrong with the whole bi/twin theory, but a supercharged/turbocharged engine does sound interesting. You would need a lot of room, and the N55 535i has a lot of room left and right side in the engine bay compared to no room at all in the N54 335i engine bay.

[The Automotive Enthusiast]

Don't fall for BMW's marketing ploy. BMW calls the N20 a TwinPower Turbo. It's not, it's a single turbo, twin scroll.

[yogi]

Originally Posted by smellfish

Bi is always better regarding cars and women

[flavius]

Originally Posted by Thumperx

I cannot believe this subject is being discussed (????).

Because?

[kyleb350]

Originally Posted by smellfish

Bi is always better regarding cars and women

I dunno man. Having twins sounds like a plus too

[Grizz258]

Originally Posted by kyleb350

I dunno man. Having twins sounds like a plus too

[GreyCoupe]

Uuuuuhhh, marketing.