The Engine That Broke All Limits

At the best of times, manufacturer participation in motorsport remains a fickle thing. Companies dip in and out of racing categories on a whim, citing vague and incredulous excuses such as “objectives reached” or “changes in corporate strategy”, which is really just corporate code for “after years of trying and billions spent, our empty trophy cabinet has forced a shareholder-pleasing retreat from factory-level racing”.

There was a time, though, that the flipside also rang true. In Formula One’s pre-ban-hammer days of the 1970s, when innovation was still revered as opposed to being reviled today – and technology was still in its infancy – nearly anything went and everyone wanted in. Think back to the Tyrell P34 six-wheeler, the first ground effect cars and, indeed, turbocharging.

Renault pioneered forced induction into the sport in 1977, followed by Ferrari in 1981, BMW in 1982 and TAG-Porsche the next year.

To balance performance against the benchmark and naturally aspirated 3-liter Cosworth DFV V8 used by nearly all on the grid, the turbo cars were restricted in capacity to 1.5-liters. Renault and Ferrari both opted for a V6 configuration for their engines, yet BMW chose to go an entirely different direction with not just four cylinders, but a production-based block whose roots hail as far back as the mid 1960s.

Using road car engine blocks is a common, cost-efficient occurrence in grassroots motorsport. Further up the competitive ladder, it’s less likely: such engines are bespoke and designed from scratch to deliver ultimate performance and reliability. That BMW looked towards such an unlikely source to serve in racing’s highest tier is already unusual. That this production-based engine evolved to the highest-powered F1 engine in history almost defies belief.

The BMW 1500 Engine Developed Just 80 hp, But In F1 Spec Had 17 Times That

The BMW 1500 Neue Klasse was produced between 1961 and 1965. As a keystone entrant in its history, apart from saving BMW from financial ruin, it’s the car that took post-war BMW into a new era and established the brand as a pre-eminent manufacturer of luxury sports sedans.

The 1500’s engine capacity was just that: 1.5 liters, distributed between four cylinders in a bulletproof cast-iron block and producing 80 hp; the former being strong, cheap and bearing excellent resistance against wear.

​​​​​​Over time, the engine – codenamed M10 – would undergo several upgrades and be featured in successive models such as the 1600, 2002 and E21-gen 3 Series, as well as being homologated for racing in up to Formula 3 and Formula 2.

Paul Rosche, BMW’s engine doyenne for more than 40 years and responsible for the piston power of all M-branded models up until 1999, including that of the McLaren F1 supercar, chose this engine for its familiarity, lightness, compactness, simplicity and durability.

A more compact engine would also deliver secondary benefits in F1, such as less weight and better weight distribution, ease of packaging, cooling and installation, the latter assisting the rear aerodynamics to work harder. Durability was enforced with titanium conrods and gear-driven camshafts.

With a KKK turbocharger fitted and fuel injection controlled by electronic management as an F1-first, in debut form the engine – now christened M12/13 – first appeared in 1982 with the Brabham F1 team, with a peak capability of 800 hp. It was naturally disposed to high-revving, being well oversquare. The latter is a preferable trait in racing engines where long, low-rev torque-producing strokes are undesirable. The downside was ridiculous turbo lag demanding a change of driving style and perfect throttle timing between corner entry and exit, to have the steering wheel straight just at the moment the turbine unleashed its tar-tearing terror.

It is alleged that Rosche had a preference for using engine blocks from the 1500 roadcars that had already covered 100 000 kilometers (62 000 miles) for the F1 application, as it was reasoned these would have been proven not to have suffered from any casting imperfections.

By 1982, the M12/13’s power could be reliably upped to 640 hp for races – a number set to skyrocket in the coming years. In fact, that was nothing against its full destructive capability when set to qualifying mode, where it developed a still-standing record 1,400 hp.

Or more.

Because nobody knows precisely how much.

Boosted Beyond Breaking Point

Paul Rosche’s timeless quote is a perfect postcard of that era’s mechanical mayhem: “It must have been 1,400 bhp, but we don’t know the exact figure since the engine didn’t go beyond 1,280 hp.”

The only way to achieve such monstrous power, was for BMW to have wound the boost up to 80 PSI and revving the engine beyond its 11,500 rpm limit, at the cost of already-laughable reliability.

Understandably, F1’s special qualifying-only engines of that period were called “grenade” engines.

These were F1’s true days of thunder, as mechanics regularly suffered constant burns from contact with red-hot exhausts and fatigue from an incessant number of engine changes over each race weekend. Spare a thought for the cars, too, that regularly suffered bent chassis tubing from wrestling the engines’ twisting forces.

It was not in vain, though, as Nelson Piquet powered to the 1983 F1 crown in the Gordon Murray-designed BT52, with BMW becoming F1’s first-ever championship-winning turbo engine just 630 days after the company entered the sport as an engine supplier. As a bonus, they’d beat Renault at their own game despite the French company enjoying a five-year head start.

The BMW M12/13 Engine Was Far More Than Just The Sum Of Its Parts

It’s easy to look back and reduce the M12/13 and its successor, the M12/13/1’s esteem to the sole value of its admittedly ludicrous four-digit power output.

Beyond that, though, the creation of the Brabham BT52 necessitated innovation. The car’s arrow shape originated as a result of moving all the available mass to the rear to aid traction, just weeks after a ban on ground effect cars for the 1983 season was instituted and rendering the convention of mounting the radiators alongside the driver useless.

Furthermore, gearbox internals would have had to be significantly beefed up, and aerodynamics adapted accordingly around optimized engine packaging. So, too, were the drivers, who had to man-handle the 1,000-hp beasts without the aid of power steering with nothing but anticipatory alertness and gladiatorial bravery to deal with the sudden onslaught of boost.

BMW Quit F1 While It Was Still Ahead

To prevent dominance by turbocharged cars, from 1984 onwards, F1’s governing body, the FIA, implemented a gradually increasing fuel capacity limit. Along with a mandated reduction in boost pressure that would start in 1987, the resultant need to save fuel hampered the turbo cars’ performance as intended.

All too aware of the M12/13/1’s vicious power resulting from a ferocious appetite for octane, BMW foresaw that these interventions would curtail future success, and withdrew from the sport at the end of 1986.

By that time, the humble 1500 sedan would have turned a full 21 years old, its creators blissfully unaware of the stratospheric heights the offspring of its M10 engine would reach in F1 – and later leaving the sport with not a whimper, but an indelible bang that still continues to inspire awe today.

no excerpt – fix

Sources: Autoevolution.com, BMW, BMWBlog.com, Enginelabs.com, Formula1.com