There are few duos in the automotive world as iconic as BMW and their beloved straight-6. From the advent of the company’s existence, this engine configuration has become as iconic as the models in which they have featured, but the most revered is arguably the naturally aspirated S54. 
It would be criminal to speak about the iconic S54 motor and not refer to the early 2000s E46 M3 which employed it and enjoyed resounding success. In fact, ignoring the whole story of the quintessential BMW sports coupe; the M3, would be omitting a key reason as to how this high-revving and iconic sounding motor which holds the headline of this article would come to be.
The BMW M3 as we know it today, is acclaimed for its engaging driving dynamics but more importantly, the straight-6 engine mounted between the front wheels. Things weren’t always like that though, nor was this recipe always followed throughout the lineup’s 36 year history. Regardless, BMW aficionados are most satisfied when this doctrine is followed.
The first creation to wear the M3 badge; the E30, actually employed a four-cylinder motor with the codename S14. At the beginning of what would become a historic and revered nameplate, engineers at the Bavarian brand were in search of a compact and lightweight motor that would give the creation an advantage when it took to the racetrack. 
It may not have been the straight-6 M20 motor which was employed in the locally-loved Gusheshe 325i, but the new E30 M3 would go on to become the most successful touring car of all time, enjoying success throughout the late 80s and early 90s. The box-flared model, equipped with clever aerodynamic upgrades, enjoyed phenomenal success off of the race track too and thus spawned a lasting legacy which remains with us today. First iterations of the M3 badge can demand a price tag of well over R1 million now but considering the production run didn’t exceed 20 000 units, they are seldom listed for sale and ever increasing in value.
For the second iteration of the nameplate, the brand eventually embraced the engine configuration for which they were most intertwined. The second generation BMW M3 finally made use of a performance-oriented six cylinder. It added two cylinders and increased displacement by as much as a litre over its predecessor, bringing the total to 3,2-litres shared among six cylinders. This isn’t common practice in the current age of downsizing but considering this was over three decades ago, the motoring world was a significantly different place and because of this, the 90s was responsible for some motor marvels; not only from BMW.
The E36’s S50 motor was capable of 236 kW and 350 N.m post-facelift in 1995 while the North American market received the slightly less powerful S52 mill which was still potent but less revered with 179 kW and 320 N.m, all compliments of emissions regulations. The E36 M3 also made the performance coupe a commercially viable venture for BMW by building on the somewhat limited success of its predecessor. By the end of its production cycle in 1999, over 71 000 units were sold employing both engine configurations above but the more powerful of the two was directly responsible for the creation of the subsequent S54.
Following the E36 M3 would be a tough act to follow but BMW’s M division are not known for resting on their laurels. They took the novel six-cylinder predecessor and improved on it, for both the drivetrain and driving dynamics. The S54 used the design of the 3,2-litre S50 while the block was fashioned from heavy but durable cast-iron. The 91 mm stroke remained unchanged while the bore was increased from 86,4 mm to 87 mm. High strength, forged components comprised the moving parts within the motor which included the crankshaft, reinforced conrods and high compression Mahle pistons.
The 24-valve cylinder head was also significantly redesigned and eventually lighter than the S50 unit on which it was based. The most notable changes were the improved VANOS system; BMW’s own variable valve timing while new cast iron camshafts were used and finger followers replaced old bucket-style lifters. Feeding a mixture of petrol and air into the chamber were individual throttle bodies that were electronically controlled; a first for an M-tuned motor. All of this work allowed the Bavarian straight-6 masterpiece to rev up to a sonorous 8 000 rpm and sing a tune that is instantly recognisable to an endearing enthusiast. 
The improved straight 6 was thus able to churn out 252 kW at 7 900 prm while its maximum torque of 365 N.m came at a much lower 4 900 rpm. The motor was lauded by all those who were fortunate enough to experience it for its linear power delivery but its party trick was undoubtedly the tingling induction and exhaust sound at full-throttle. The undeniable swan song of the range was the M3 Coupe Sport Leichtbau, or Coupe Sport Lightweight which did just as the name stated while extracting a bit more power from the mill. In this most powerful form, the S54 came with 13 kW and 5 N.m more than its base counterpart, compliments of sharper profile camshaft and a larger air intake with a lightweight carbon fibre manifold. 
A total of 86 000 E46 M3 units were produced until its lifecycle came to an end in August 2006 but the motor soldiered on until 2008, being the solitary choice for the less successful E85/E86 Z4 M series. The revered S54 was expectedly showered with awards from its inception until 2006, with the most notable including the Best New Engine award in 2001 and the International Engine of the Year in the same year; worthy awards for the Bavarian straight 6 masterpiece.
