The inline-six is BMW’s bread and butter. Indeed, the brand has been making them since at least the 1930s, with the M78 debuting in the BMW 303. Later, the brand received acclaim with rock star six-cylinders like the M88 in the mid-engined BMW M1, praised for its output, sonorous snarl, and race heritage. Much later, the S54 debuted in the E46 M3, setting a benchmark by churning out over 100 horsepower per liter.
And while the BMW M engines deservedly get a lot of the headlines, there are a number of inline-sixes that kind of fly under the radar. One of them is the N52 engine, which replaced the M54 engine in the mid-2000s. Turns out, the only inline-six without a direct M equivalent is actually the one you want.
What Makes the N52 Engine Great
Along with mainstays like the M54 and M50 engines, the N52 engine is a direct descendant of the original BMW M30 engine. But only the N52 sports a magnesium and aluminum block, making it lighter than its predecessors. A higher redline and introduction of Valvetronic variable valve lift allowed the engine to be more responsive and more powerful than the older M code engines, too.
In the real world, the N52 has other, less tangible selling points. It made its way under the hood of almost every model in BMW’s stable at the time. From the Z4 to the X1 to the 740i, there’s an N52-powered car for everyone. That means spare parts are extremely available and no shortage of DIY materials (videos, walkthroughs, etc), making N52 ownership easy and…dare we say it, relatively inexpensive.
Downsides of the N52
Nothing is perfect, and the N52 is no exception. For one, the N52 is far from exotic. It lacks the character that makes engines like the S54 feel truly special. It’s also far from a powerhouse, making just 255 horsepower in its highest-output N52B30 guise. Compare that to the S54 – which made over 330 horsepower – or contemporary turbo units like the N54 (300-ish horsepower). Easy to see why the N52 gets overlooked by enthusiasts poring over spec sheets.
The only other real drawback the N52 has is its limited aftermarket support. While you can do the usual tuning, intake, and exhaust modifications, real power gains are limited and aren’t a terribly value-packed proposition. For real power, you’ll have to shell out for a supercharger…which gets pricy quickly, even when doing your own work. Notably, all these downsides are also inadvertent contributing factors to (or byproducts of) the N52’s reputation for reliability.
The N52 Engine is Critical to BMW’s History
As we briefly mentioned, the N52 never got an M equivalent. Whereas the M54 and M52 got the S54 and S52, and so on, BMW never invested in an S variant of the N52. The E90 M3 was slated to receive the much more exotic and powerful V8 engine derived from the V10 in the E60 M5. So there was no need to invest in a high-output six-pot. Which is a bit of a shame; a magnesium/aluminum M inline-six, while presenting some interesting engineering challenges, is an exciting prospect.
Indeed, the N52 proved to be the last inline-six without forced induction that BMW ever made. Barring, of course, the rest-of-world N53 engine which utilized direct injection instead of port injection. For that reason alone, it’s important. The icing on the cake is that the last of the naturally aspirated is also perhaps the best BMW ever made.
First published by https://www.bmwblog.com
Source: BMW BLOG
