Originally Posted by mkoesel
I don't think it will be called the S55Tu simply because the N55 was designed from the outset with Valvetronic. BMW added the Tu suffix to the S63, and later then N63, when those gained Valvetronic throttle operation. That upgrade won't be happening with I6 engine family, so there will be no need for the name change.
I was under the impression that Technische Ueberholung designated an upgrade from the normal marque. The N54Tu =?= N54B30To (I think, I could very well be wrong) was the 1M's engine and AFAIK all that was different from the N54Oo (where Oo denotes high output) was the Overboost functionality in software, made possible by a better cooling system.
I do have a question for you. Do you think there is a possibility of a larger displacement I6? (I remember reading that the best size was .5L/cylinder for maximum output.)
for the intelligent reply