NP, I wasn't really hear to defend the 335is or took your comments as a critique. Its probably off topic but the 335is adds an extra oil cooler, water cooler, and larger fan, tuned software, free flowing exhaust, stiffer motor mounts for the twisties and likely other tweaks such as fixing problems with the high pressure fuel pump. The engine bay appears "cleaned up" over the older N54. Do we know all parts that have changed and swapped for reliability in general, no I don't think anyone has done that.
From what I know BMW was aware of high heat being generated in some cylinders from the early N54 over boosting. They've solved that problem apparently with some special coating which they specifically wanted to do in order to give the N54 a higher output. Therefore giving the N54 engine used in the 335is Z4is and 1M engine its own designation "N54HP" or officially "N54B30TO". Each version is specifically tuned with the best tuning performed by the M division for the 1M. The Z4 and 1M have more HP according to BMW because the 335is has a more restrictive intake. I noted looking at parts that it may be at the intercooler duct.
The 335is has a higher overboost output than a standard recent N55 335i. However track data reveals that BMW de-tuned the N54 compared to "some" (2006, 2007) early N54 engines. It appears that not all early N54's had as much as others (engine variance).
Looking back the the 335is test, I wonder if they were in "D" mode and used the paddle shifters. They stated they were paddle shifting. The problem is "D" is not a sport mode and also if your in "D" and use the paddle shifters, it temporarily puts it into manual mode and when no shifts occur will switch back to "D". This is handy if you want to temporarily shift and then let the car take over again. Otherwise they need to be in "S" mode and then use the paddle shift to have full manual control. Their story almost eludes they were in "D" because they said the transmission sometimes didn't register a command.
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Originally Posted by NurEinser
Good point. I wasn't ragging on the 335is, but now I wonder if a PPK'd early N54 135i would match the 335is numbers.
Which brings me to my question, what has changed in the N54 over the years?
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