Quote:
Originally Posted by mkoesel
The 135is uses the N55 @ 320hp.
The N54 will die with the current cars that still use it (E89, E92). The F80 M3's engine will either be based on the N55 (making it an "S55") or on the new generation of I6 that BMW has been working on for the past few years. The latter would make a lot of sense since it has been reported that the target for that engine is up to 400hp for non-M applications. An M application would hit 450hp easily, maybe as much as 480hp or so.
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I don't think BMW has the technology right now for fuel efficient 400hp engines (on their standards) for use in non-M cars. That's why they go hybrid. They will add the power via electric engines.
I am very curious if BMW uses Valvetronic on their next M3. This is the essential difference between N54 and N55, not the turbo differences (two versus one twin-scroll). In fact, Valvetronic makes it possible to use one turbo and still have no lag, so it's a combination. I remember the Valvetronic being left out from the previous M3 because of problems at high engine speeds. The next engine will probably also rev to like 7500RPM, otherwise I can't see how they can pass 430hp with a 3-liter engine. And I do think it will be a 3-liter, because they need fuel efficiency and small displacements are critical for this (not sure how Mercedes does it with their monster 5.5-6.3L engines).
The problem with the N55 is that it has weak internals: the crankshaft is not forged like the N54 and the pistons are not made by Mahle (like in the N54) but by a Turkish company. Also the N54 has forged piston rods, and I'm not sure that the N55 has them. An S55 based on N55 will probably be in fact a brand-new engine, with new, more efficient cylinder head (probably with Valvetronic) and also forged internals.
The N54 has been said to be a de-tuned 400hp engine. Based on how much abuse this engine takes and the current tuned power levels (450 crank hp easily hit with stock turbos, and 700hp hit with single large turbo) I tend to think this was true.