The naturally aspirated gasoline engine is dead. As dead as 15″ wheels and roll-up windows. A generation from now no one under 25 years old will even know the experience of winding up a BMW inline six without a turbo sucking exhaust gasses out of it.
The need for efficiency and ever increasing performance have dictated a sea-change that will alter what we’ve known BMW’s to be forever. Consider the following the fact: the E9X M3 will be the last naturally aspirated M product. Or (even more shocking) that the current 128i, 328i and X3 28i are the last naturally aspirated BMW products to be sold in the US. Once those three models are gone it’s all turbos for as far as the eye can see.
From the 16 valve V8 found in the 507 to the 500 hp V10 under the hood of the E60 M5 BMW has had a long and storied history when it comes to the engines that motivate its cars. The soul of these cars have been unadorned with turbos or superchargers (with an exception or two) from the early part of the 20th century until the early 2000s. Production BMWs have been celebrated as naturally aspirated affairs. It’s a simple theory at the the heart of complex machine; perfect weight distribution and nothing in the way of complete control and feel. For engineers in Munich that meant anything within the engine that would reduce the ability to rev (heavy flywheels aside) or the connection from the driver’s foot to acceleration wasn’t a part of the package. And for many years it made sense at every level. Turbos were meant for such lowly brands as Audi who had to make do with the scraps of a VW empire. Or Porsche, saddled with flat six architecture that was mandated by hanging the engine out the back.
Over the years BMW excelled at this formula. For more than a generation engineers in Munich continued to perfect the formula. From the smallest inline six to the largest V12, every BMW engine held true to the theory that control and performance meant forced induction was not part of the answer.
Even despite the radical turbocharged engine on the 2002 Turbo, race cars such as the 320i Turbo or the legendary 1.5L M12 in the Brabham F1 car (which produced over 1300 hp in qualifying form), BMW was dedicated to its formula in street cars.
In series production the book-end came in the form of an inline six and a V8. The last top-line naturally aspirated inline six was the quick-revving 3.0L N52 that produced 272 hp in European form. But perhaps the pinnacle of BMW’s long history with naturally aspired six’s came with the E46 M3 and the S54B32. 333hp in US form (and up to 355 in CSL trim) the 3.0L sounded and revved like a race-car.
But if you’re talking about the ultimate naturally aspired BMW engine, that would technically have to be the S85B50 V10. With 507 hp at 7750 rpm the 5.0L V10 blew away all comparable engines when it came to displacement vs power. With a 8250 redline the V10 was inspired by the high-revving BMW F1 engines of the era. It didn’t sound as great as the V8 it replaced (we’ll blame EU noise laws for that) but it was dramatically more exotic.
Then BMW did one better and sliced off a couple of cylinders to create the high-revving 4.0L V8 for the E9X M3. The S65B40 produced 414 hp and a 8400 rpm redline that defied all belief. While some of the BMW historical M3 character was lost with the S54B32, the new V8 threw the gauntlet down on the competition and helped continue the M3′s dominance over the Audi and Mercedes competition.
And then just like that the 8,000 redlines were gone.
Progress should give us more of what we want. But we’re finding out the future is too complicated for that. Yes the new era of BMW engines develop more torque and are better at every day drivability. But there is a character that will soon be forever lost with these engines. The honesty of a naturally aspirated engine will soon be forgotten and in its place the induction sound and endless torque. Yet another old technology that progress has made irrelevant.
My fear is that the accelerator will soon become the go button and the nuances of power delivery we all know and love will be gone. And gone too will be listening to an engine take on new character at every thousand RPM up the dial – the very soul of an engine.
So what do we have to look forward to? Speed for one. We know that BMW will up the ante in every way with these new turbocharged monsters. We also should expect smaller engines producing the same if not more power. And that means less weight and (most importantly in the eyes of society) much higher efficiency.
All is not lost but quite a bit of what BMW has hung their hats on for the past 40 years will be. Thus it’ll be up to the mad scientists of Munich to find BMW’s voice in this new world. They have a a tough road and there’s an enormous amount at stake. But if there’s one thing we’ve learned to do, it’s to trust them when it comes to designing and building powerplants.
Or you can just start scouring eBay for that pristine E46 M3.