Get this... I was told this yesterday by a close friend of mine, returning from a trip to the BMW plant in Munich, that a new high revving 4 cylinder in development may have 3 Turbos.
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Originally Posted by atr_hugo
Wrote an article on the N55 for the local chapter BMW CCA mag. it incorporates Valvetronic (they managed to squeeze it into the cylinder head with double Vanos, spark plugs and direct injectors - phewwww!).
The Twin-Power turbo is basically the same turbo that's used on the V8 - it's a twin scroll (two chamber) on the exhaust side. So rather than an exhaust pulse arriving every 240 degrees of crank rotation (as on the individual turbos of the N54) an exhaust pulse arrives every 120 degrees of crank rotation. That allows peak /RPM/ should read torque/ to occur at 1200 RPM, so it is less 'lagy' then the N54.
The Valvetronic allows the engine to go 'throttleless' after startup, that's where the fuel savings comes in.
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