BMW S38/M88 Engines: Unraveling the Legacy of Performance and Racing Heritage

Ladies and gentlemen, start your engines! No, seriously — if you’ve got a BMW S38 or M88 under your hood, you’d better let that beast growl. Because today, in this latest installment of “The Power Plant,” we’re diving headfirst into the heart and soul of BMW’s legendary racing pedigree: the S38 and M88 engines. These mechanical marvels powered some of the most iconic Bavarian brutes, including the prodigious M1 and the epoch-making E28 M5.

Picture this: It’s the late ’70s, and BMW’s engineers are chomping at the bit to create something extraordinary, something that would obliterate the competition and sear their mark into the annals of automotive history. Enter the M88, a fire-breathing, 3.5-liter inline-six that began its life as the power plant for the groundbreaking BMW M1. The M1, you say? Oh, yes, friends — we’re talking about the car that put the “M” in “OMG.”

Now, fast-forward to the mid-’80s, and you’ll find the S38 nestled beneath the hood of the E28 M5, the world’s fastest production sedan at the time. Equipped with individual throttle bodies, a double-row timing chain, and forged pistons, the S38 wasn’t just a racing-inspired engine; it was a veritable engineering tour de force.

So, grab your driving gloves and strap in, as we traverse the winding roads of history and technical mastery that define the S38/M88 engines. From the straights of Le Mans to the twists and turns of the Nürburgring, we’ll explore how these motors propelled BMW’s racing legacy to new heights and etched the brand’s name in the annals of automotive excellence.

In the words of the immortal Mario Andretti, “If everything seems under control, you’re not going fast enough.” Well, with the S38/M88 at full throttle, control might just be overrated.

The Genesis: BMW M88 Engine

Ah, the late ’70s — a time of disco, questionable fashion choices, and some seriously groovy automotive dreams. BMW was hungry for a win, eager to show the world what their Bavarian brains could cook up. And what better way to achieve that than by developing an engine that would leave the competition in a cloud of dust and envy? Enter the M88, an engine that would prove to be nothing short of revolutionary.

BMW M88/3 (1983-1989). BMW AG

BMW’s engineers had a clear mission: create an engine that was powerful, reliable, and efficient — a tall order in an era when horsepower and fuel economy were often considered mutually exclusive. But these engineering wizards weren’t just up for the challenge; they were practically salivating at the prospect of pushing the limits of automotive technology.

Origins of the M88 Engine

In the mid-1970s, BMW’s motorsport division was eager to build on the success of the M49 engine, which powered the BMW 3.0 CSi to numerous racing victories. The decision was made to create a new, independent sports car capable of competing in both Group 4 (special GT vehicles) and Group 5 (sports cars) racing categories. The result was the legendary BMW M1, and at its heart lay the M88 engine.

The M88 engine’s design drew its inspiration from the M49 engine. Utilizing the crankcase of the high-volume M06 engine, the M88 featured a four-valve cylinder head, with the camshafts driven by a two-row chain for reduced noise production.

The cylinder head was designed in two parts: the lower part formed the combustion and water chambers, while the upper part housed the camshaft bearings and bucket tappets.

With a bore of 93.4 mm, the M88 engine had a land width of 6.6 mm between the cylinders. To ensure this, the M88 crankcases were tested with the two-valve cylinder heads of the mass-produced engines. This hybrid M90 engine powered the sporty 635CSi model from 1978 to 1981.

The M88 engine, equipped with Kugelfischer injection and individual throttle valves for each of the six intake manifolds, produced an impressive 277 hp. This power output would propel the BMW M1 to victory in various racing events. However, the M88/1 engine, intended for Group 4 competition, couldn’t be homologated and used in time.

As a result, BMW introduced the Procar racing series in 1979 and 1980. The M88/1 engine, through tuning measures, achieved an astonishing 470 to 490 hp. These modifications included a new camshaft, larger valves, optimized ports, sliders instead of throttle valves, a new exhaust system, forged pistons, and more.

The M88/2 engine, intended for Group 5 racing, was built in limited numbers. Boasting two exhaust gas turbochargers and other optimization measures, this powerhouse of an engine churned out an incredible 850 to 950 hp.

The Birth of a Legend: BMW M88 Engine

The M88 engine was designed to be a force to be reckoned with, using innovative engineering techniques and state-of-the-art technology. One of its most distinctive features was the two-part cylinder head design. The lower part of the cylinder head formed the combustion and water chambers, while the upper part housed the camshaft bearings and bucket tappets. This unique design allowed for greater efficiency and performance.

The M88 crankcases were also utilized in the M90 engine, a hybrid variant that combined the M88’s advanced technology with the mass-produced engines’ two-valve cylinder heads. The M90 engine powered the sporty 635CSi model from 1978 to 1981, showcasing the M88’s versatility and adaptability in various vehicle applications.

At the heart of the iconic BMW M1, the M88 engine produced an impressive 277 hp, thanks to its Kugelfischer injection system and individual throttle valves for each of the six intake manifolds. This power output allowed the M1 to conquer racetracks worldwide, solidifying the M88’s legendary status.

The M88/1 engine, designed for the Procar racing series, took the M88’s performance to a whole new level. Through extensive tuning measures, including a new camshaft, larger valves, optimized ports, sliders instead of throttle valves, a new exhaust system, and forged pistons, the M88/1 engine’s output skyrocketed to a staggering 470 to 490 hp.

In addition to the M88/1, BMW also developed the M88/2 engine for Group 5 racing. This remarkable engine boasted twin turbochargers and other optimization measures, resulting in an incredible 850 to 950 hp output. Although built in limited numbers, the M88/2 showcased the full potential of the M88 engine and further solidified its place in BMW’s racing heritage.

The Evolution: BMW S38 Engine

As the M88 engine continued to impress both on and off the racetrack, BMW sought to further refine its design and performance. The result was the evolution of the M88 into the S38 engine, which would go on to power several iconic BMW models.

S38B38 Engine. BMW AG

From 1985 to 1987, the M88/3 engine was used in the M5 sedan, and from 1983 to 1989, it found a home in the M635CSi coupé. With minor improvements, the M88/3 engine now achieved an output of 286 hp.

Despite the technical proximity to the well-known predecessor, the old engine designation M88 was still used. Internally, the system had already transitioned to the new designation – the engines of Motorsport GmbH were given an “S” as the code letter.

The previous M88 was based on the large six-cylinder engine, leading to the first code number being 3. The series’ basic engine was the M30 version, and the second number chosen was 8. This new designation, S38, not only provided space for potential large-scale variants but also created a memorial bridge to the revered M88.

The S38B35 engine, the first catalytic converter version of the four-valve engine, was otherwise identical to the M88/3 engine but delivered a slightly reduced output of 260 hp. It was used in the M635CSi as well as the US version of the M5.

The S38B36 engine, in production from 1988 to 1992, featured an increased displacement to 3.6 liters by enlarging the stroke from 84 to 86 mm. This led to a power output of 315 hp. The engine also boasted a new gas exchange design, including optimized channels, a new camshaft, increased valve lift, an air collector with a resonance system, a de-throttled exhaust system with a multi-tube manifold, and a large-scale catalytic converter and rear silencer system.

Motorsport Achievements

Let’s talk about the ultimate test of an engine’s mettle: endurance racing. With its roots in the M88, the S38 was born with a taste for the high-stakes world of 24-hour races. In the crucible of Le Mans, where engines are pushed to their absolute limits, the S38 proved its worth, powering BMW M1s and other race-prepped machines to impressive results. The roar of the S38 as it blazed down the Mulsanne Straight is a sound that will forever echo in the hearts of BMW enthusiasts and racing aficionados alike.

Henzler in BMW M1 in Zolder (1981). BMW AG

The S38’s racing resume didn’t end at endurance events; it also left an indelible mark on the world of touring car racing. Nestled under the hood of the E28 M5, the S38-powered beast tore up circuits around the globe, claiming trophies and accolades in various touring car championships. The S38’s potent combination of power and reliability made it a formidable contender, one that could go toe-to-toe with the world’s best and come out on top.

But it wasn’t just factory-backed teams that benefited from the S38’s racing prowess. Privateer teams also got their hands on these magnificent machines, proving that the S38 was an engine that could excel in the hands of both seasoned pros and ambitious amateurs. With the S38 under their hoods, these privateers tasted victory and cemented the engine’s reputation as a force to be reckoned with on the racetrack.

In Conclusion

So, my fellow Bimmerists, as we reach the end of this thrilling journey through the annals of BMW’s racing heritage, let’s take a moment to appreciate the profound impact of the S38 and M88 engines. These mechanical masterpieces not only powered some of the most iconic BMW models in history but also played an instrumental role in defining the brand’s performance-oriented image. With their groundbreaking innovations, relentless pursuit of performance, and indomitable racing spirit, the S38 and M88 engines truly represent a golden era of automotive engineering.

As we look back on the legacy of these magnificent engines, it’s clear that their influence extends far beyond the realm of BMW enthusiasts. The S38 and M88 have left an indelible mark on automotive history, serving as a testament to the power of engineering, passion, and the relentless pursuit of performance. As we continue to push the boundaries of automotive technology, let us not forget the engines that paved the way, the engines that proved that with a little ingenuity and a lot of determination, anything is possible.

And so, as we turn the key and fire up our beloved Bimmers, let us remember the spirit of the S38 and M88 engines, the soul-stirring howl of their inline-six symphony, and the unquenchable thirst for victory that they embodied. For it is in these engines that we find the essence of what it means to be a true Bimmerist — a passion for performance, a love of engineering, and an unwavering devotion to the pursuit of driving perfection.

Georg Meier

BMW technician since 1996. I began my automotive journey in 1993 as an apprentice mechanic at Automag, the world's oldest BMW dealership in Munich. With years of experience and dedication, I garnered a wealth of knowledge about the intricacies of BMW and MINI vehicles. The love/hate relationship with the brand led me to found BIMMERIST where I share expertise and insights with fellow enthusiasts.

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