If you are a BMW fan, surely you are no stranger to inline 6 engine configurations. Of course, BMW does not have a monopoly on the L6 use, and for some of you the quintessential L6 might have originated from Jaguar, Triumph, Aston Martin, Mercedes or Nissan among many of the manufacturers that used that config… One thing is for sure, no one can be indifferent to the metallic melody that L6 engines produce!
The first BMW L6 for automotive application was born in 1933 and produced a whopping 30hp – don’t laugh, that would probably be equal to 300hp today! The tiny 1.2L M78 engine was derived from an existing 4 pot (M10) by simply adding 2 cylinders to their creation to improve power and allowing a more linear power delivery. The M78 was only used on the 303 but was modified and improved year after year until its final version featured in the 327 model until 1953. In its final form, the 2.0L M78 produced 55hp which was achieved through the upgrade of many parts including cylinder heads or carburetors.
Moving forward to 1968 and the M30 design which BMW properly amortised as they used it until 1994 and acclaimed for their smoothness and efficiency with their characteristic inclined bank of cylinders. The first use of the M30 unit was for the E3 2500 and produced 150hp. At the end of its lifespan, the M30B35 unit produced up to 210hp with a 3.5L displacement.
There are way too many variants of BMW L6 to list here, and even more so from other manufacturers who came up with legendary versions of their own. To name a few, the Nissan RB28DETT featured in the Skyline, the e-Type 3.8 and 4.2, the Aston DB5 or the Toyota 2JZ… Feel free to comment on the many other L6 out there that haven’t been mentioned!
Having personally owned and rebuilt multiple BMW straight 6s, my view and opinion might be a bit biased… But I do think they are some of the most exquisite and enjoyable engines to use with their characteristic noise, power delivery and behaviour, making them as enjoyable to cruise with as they are to race. Especially with the S54 variant featured in the E46 M3, which is for many BMW fans the best straight 6 that ever came out of the Munich factory. Personally, I think I’d go with the M88 which has that proper mechanical construction which is hard to find in newer models.
